JP3447285B2 - Non-aqueous secondary battery - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous secondary battery, and more particularly to a non-aqueous secondary battery having a specific structure for ensuring safety while increasing capacity.

[0002]

2. Description of the Related Art A non-aqueous secondary battery represented by a lithium ion secondary battery is a secondary battery using an organic solvent as a main solvent of an electrolytic solution. This non-aqueous secondary battery has a large capacity,
Moreover, because of its high voltage, high energy density, and high output, demand tends to increase more and more. Currently, using LiCoO ₂ (lithium cobalt oxide) as the positive electrode active material,
A lithium ion secondary battery using a carbon-based material as a negative electrode active material has been commercialized, but this battery is different from a conventional non-aqueous secondary battery using a lithium metal as a negative electrode for high capacity, A paste in which the above active material is dispersed in an organic solvent together with a binder and the like, and a positive electrode current collector, a negative electrode current collector, and a coating film containing the active material on each of both surfaces of the current collector are prepared using this paste. Formed and used as a positive electrode and a negative electrode, respectively. Then, a battery is constructed by inserting an electrode body obtained by spirally winding these strip-shaped electrodes via a separator into a negative electrode can.

By the way, in this non-aqueous secondary battery, a mixture of a cyclic ester such as ethylene carbonate, which has been a flammable organic solvent, or an ester such as dimethyl carbonate or methyl propionate, has been used as a main solvent of the electrolytic solution. Has been used. Therefore, special attention has been paid to the design for ensuring safety.As a safety mechanism, a shutoff vent is provided in the sealing body to prevent the negative electrode can from rupturing due to gas generation, and overcurrent protection has been used. Has a PTC element in the negative electrode can in order to prevent heat from flowing into the battery, or has a shutdown mechanism that blocks the migration of lithium ions by sealing the pores of the separator that are welded at high temperatures. Something has been done.

[0004]

However, according to the research conducted by the present inventors, this non-aqueous secondary battery may be a battery depending on the case where the capacity is further increased and the specifications required by the user. It has been found that if the structure of the power generation element itself is not further devised, it may not be possible to adequately address safety issues. In other words, it has been revealed that the safety test tends to lack safety in a safety test under harsh conditions such as a crush test, a nail piercing test, and an external short-circuit test, which are intentionally assumed to be abnormally used.

For example, the crush test described above assumes that the battery is intentionally crushed by some accident, but in this crush test, the lead body welded to the negative electrode current collector passes through the separator. It has been found that a short circuit is likely to occur when facing the positive electrode. It is considered that this is because the lead body of the negative electrode pierces the separator when the battery is crushed. Also, since the negative electrode can also serves as the negative electrode terminal, a short-circuit current will flow when the negative electrode can comes into contact with the positive electrode of a different polarity during the crushing test. Will increase. Further, when the separator that wraps the electrode body is melted by the heat generation, other parts of the positive electrode may also come into contact with the negative electrode can and a secondary internal short circuit may occur. Furthermore, in a non-aqueous secondary battery that uses an electrode provided with a coating material containing an active material on a current collector, when a foreign material such as a metal piece is mixed in the production process or when a wound electrode body is inserted into a negative electrode can. The active material often falls off. Usually, the positive electrode and the negative electrode are separated by a separator, so short-circuiting is unlikely to occur due to these foreign substances, but when the foreign substances are large, it is known that these foreign substances are present in the negative electrode can during the crush test. A short circuit (soft short) may occur, which may trigger an internal short circuit.

The nail penetration test surely short-circuits the battery at a portion smaller than that caused by crushing the battery or external short circuit.
The current concentrates on the short-circuited area, which makes it easier to generate heat, and the temperature of the battery tends to rise rapidly. Since a large amount of heat is generated by the reaction with the negative electrode, this nail penetration test is a severe safety confirmation test so that a lack of safety that cannot occur under normal use conditions can be found. Therefore, if it is possible to confirm the safety by this nail penetration test, it is considered that the safety can be secured even if an abnormal use is encountered.

If the nail penetration test is carried out at a high temperature of 45 ° C. rather than at room temperature, the temperature of the battery tends to rise to a higher temperature and the thermal runaway reaction of the battery is more likely to occur. further,
It is better to stop the nail in the middle of the battery like ½ nail stick
Short-circuited parts are reduced and the current is more concentrated and heat is easily generated. Therefore, if this nail penetration test is performed at 45 ° C and 1/2 nail penetration is performed, it becomes a very severe test as a test for confirming safety, and the safety is confirmed by a test under such severe conditions. If possible, it is considered that sufficient safety can be secured in actual use.

Further, in order to confirm that the non-aqueous secondary battery is highly safe, a forced external short-circuit test for connecting the positive electrode and the negative electrode is performed after the battery is charged to, for example, 4.2 V or more. However, as battery energy becomes higher, a large current will flow when an external short circuit occurs. Therefore, the separator, which comes into contact with a portion having a relatively high resistance inside the battery, is melted, causing a secondary internal short circuit, and the battery is likely to be partly rapidly heated to a high temperature. Further, similar to the above crushing test, when the separator between the electrode body of the winding structure and the negative electrode can is melted, a short circuit occurs due to contact between the positive electrode and the inner wall of the negative electrode can, and foreign matter in the negative electrode can. If they exist, if the foreign matter has a high resistance, short-circuiting of a portion where a micro short-circuit has occurred may result in local heat generation even at the location where the short-circuit occurs. Therefore, if the safety can be confirmed by this external short-circuit test, it is considered that the safety can be secured even if such an abnormal use is encountered.

Also, the external short-circuit test is 4 times better than that at room temperature.
Performing the test at a high temperature of 5 ° C makes it easier for the battery to reach a higher temperature and causes a thermal runaway reaction of the battery. It becomes a severe test, and if the safety can be confirmed by the test under such severe conditions, it is considered that sufficient safety can be secured in actual use.

Due to the recent trend toward higher capacity, the energy density of batteries tends to become higher and higher in the future. Therefore, the crushing test and the nail penetration test, which are safety confirmation tests under the severe conditions as described above, Furthermore, it has been found that it is necessary to ensure high safety even in the external short-circuit test, and for that purpose, it is necessary to change the internal structure of the battery to a structure that does not easily ignite.

Due to the above-mentioned circumstances, the present invention is sufficiently prepared for a future increase in capacity, even in a crush test, a nail penetration test, and an external short-circuit test, which are safety confirmation tests under severe conditions. It is an object of the present invention to provide a highly safe non-aqueous secondary battery by improving the battery structure so that safety can be confirmed.

[0012]

The present invention has been made to solve the above-mentioned problems, and as a result of intensive studies on the structure of a non-aqueous secondary battery, at least a part of the positive electrode current collector was found. Is a positive electrode having a positive electrode active material-containing coating film formed on both surfaces thereof, and a negative electrode having a negative electrode active material-containing coating film formed on both surfaces of at least a part of the negative electrode current collector. A non-aqueous secondary battery in which an electrode body having a winding structure is housed in a negative electrode can, wherein an electrode of the winding structure electrode body facing the negative electrode can is substantially composed of a negative electrode. The positive electrode of the positive electrode current collector is provided with at least one outermost peripheral portion of the positive electrode of the positive electrode current collector in the spiral structure, which has at least one portion on which the positive electrode active material-containing coating film is not formed. The part where the active material-containing coating is not formed faces the negative electrode through the separator. And by adopting a structure in which the lead body welded to the negative electrode current collector in a specific form as described later does not directly face the positive electrode via the separator, while achieving high capacity, a crush test, a nail penetration test and further The inventors have found that a highly safe non-aqueous secondary battery can be obtained that exhibits excellent safety even in a severe safety confirmation test such as an external short circuit test.

The process of completing the present invention and the reason why it is possible to secure high safety while achieving high capacity by the above-mentioned structure will be described in detail below.

The most common type of electrode having a wound structure in a non-aqueous secondary battery such as a lithium ion secondary battery is a positive electrode made of aluminum foil or the like in order to increase the capacity per volume into a high capacity battery. At least a part of the current collector has a positive electrode active material-containing coating film formed on both sides. At least a part of a negative electrode current collector composed of a strip of positive electrode and copper foil. The one strip-shaped negative electrode on which is formed and two separators are stacked in the order of the separator, the negative electrode, the separator, and the positive electrode, and are spirally wound so that the negative electrode is on the outer peripheral side of the positive electrode.

Therefore, the present inventors have obtained a lithium ion secondary battery which has the above-described wound electrode body and is most popular as a non-aqueous secondary battery, and has a crush test and A nail penetration test and an external short-circuit test showed that the risk is low with ordinary commercial lithium-ion secondary batteries,
It was found that the risk of this lithium ion secondary battery increases as the energy density is increased. That is, a compound such as a carbon material that can insert and remove lithium is usually used for the negative electrodes of these batteries. It was found that an exothermic reaction occurs between the electrodeposited lithium and the carbon material in which lithium is inserted.

Also in the positive electrode, the desorption of lithium lowers the reaction initiation temperature with the electrolytic solution.
May generate heat from around ℃. Then, when the temperature further rises and reaches the thermal runaway temperature of the positive electrode, the battery causes abnormal heat generation. Due to the exothermic phenomenon associated with such a continuous reaction, when the chargeable / dischargeable capacity of the battery at a full charge is 130 mAh / cm ³ or more per unit volume of the wound structure electrode, Safety is reduced.

The volume of the electrode body having the winding structure referred to here is
The volume of the positive electrode, the negative electrode, and the separator wound is the bulk volume in the battery, and does not include the holes left when the winding shaft used when spirally winding is removed. In short, it is the sum of the bulk volumes occupied by the positive electrode, the negative electrode, and the separator. These three volume factors are important factors that determine the capacity of the battery, and regardless of the size of the battery, the discharge capacity per unit volume of the wound electrode body (discharge capacity / wound structure electrode body). The capacity densities of the batteries can be compared by calculating the (volume).

The discharge capacity referred to here is the discharge capacity when the battery is charged and discharged under standard use conditions. Then, by measuring the discharge capacity under this standard use condition, the chargeable / dischargeable capacity at full charge can be known. If standard use conditions are not specified, 25 ° C, 1C
(Current that can discharge the battery in 1 hour) is charged to 4.2V, and after reaching 4.2V, constant voltage charging is performed, charging is completed in 2 and a half hours of charging, and the charging is completed at 0.2C. Discharge to 75 V and calculate the capacity.

That is, as the dischargeable capacity per unit volume of the wound electrode body increases, the amount of heat generation per unit volume increases when heat is generated during overcharge, and the battery temperature reaches the thermal runaway temperature of the positive electrode. It is more likely to rise. Therefore, it is necessary to control heat generation better in a battery having a larger discharge capacity per unit volume so that the battery temperature does not rise to the thermal runaway temperature of the positive electrode. Further, even when the volume of the wound electrode body is large, it is difficult to dissipate heat.
In the present invention, when the volume is so large, specifically, the volume of the wound electrode body is 10 cm ³ or more, and particularly 11 cm.
^Even if it is applied in the case of ³ or more, the safety can be ensured, so that the effect is remarkably exhibited, and a preferable result is obtained.

In the present invention, the positive electrode current collector only portion is substantially formed without forming a positive electrode active material-containing coating film on the outer peripheral surface side of the positive electrode current collector at least at the outermost periphery of the positive electrode in the wound electrode body. Of the positive electrode current collector, the portion of the positive electrode current collector where the positive electrode active material-containing coating is not formed faces the negative electrode through the separator, and the lead body welded to the negative electrode current collector passes through the separator. The reason why the safety can be improved by not directly facing the positive electrode is considered as follows.

As described above, by using a compound capable of deintercalating lithium such as a carbon material in the negative electrode, the reactivity between the electrolytic solution and the negative electrode at high temperature is lower than that in the case where lithium metal is used in the negative electrode. However, since the positive electrode active material-containing coating film is formed on both sides of at least a part of the positive electrode current collector, the capacity of the positive electrode that can be charged and discharged is increased, and thus the reactivity with the electrolytic solution is increased. As a result, the amount of heat generated increases and the temperature of the battery easily rises. However, the positive electrode active material-containing coating film is not substantially formed on the outer peripheral surface side of the positive electrode current collector at least at the outermost peripheral portion of the positive electrode in the wound electrode body, and the positive electrode active material of the positive electrode current collector is not formed. By facing the part where the substance-containing coating film is not formed with the negative electrode through the separator, the local heat generated when the nail is pierced in the nail piercing test is higher than when the positive electrode active material-containing coating film is present. As a result, the heat is dissipated faster, the positive electrode is less likely to reach the thermal runaway temperature, the battery is less likely to generate abnormal heat, and the safety of the battery is improved. That is, with the above configuration, since the charged positive electrode active material does not exist at the first short-circuited portion of the outermost peripheral portion, even if heat is generated, it is difficult to reach the thermal runaway temperature. Then, although the charged positive electrode active material is present at the second short-circuited portion as seen from the outer peripheral side of the electrode body, the current flows in accordance with the first short-circuited portion, so that only the second short-circuited portion is the first Since half or less of the current flows, the temperature rise of the charged positive electrode active material is suppressed, and it is difficult to reach the thermal runaway temperature.

Further, in the crush test, the lead body provided on the electrode becomes a convex portion on the electrode, and a large concentrated stress or a twisting stress is easily generated on this portion. Then, by injecting the electrolytic solution, sealing and assembling the battery and charging, since the electrode body swells due to the swelling of the active material, particularly the swelling of the negative electrode active material, the above-mentioned concentrated stress and twisting stress further increase, The electrode body becomes distorted. In such a case, the lead body welded to the negative electrode current collector is strongly pressed against the separator, and a metal material harder than the negative electrode active material-containing coating film is used for the lead body. When the electrode body having the structure is crushed, the separator is easily pierced, which easily causes an internal short circuit. Further, in a structure in which both the positive electrode and the negative electrode are present in the outermost peripheral portion of the wound electrode body, the negative electrode can facing the wound electrode body on the outer peripheral side acts as a different electrode with respect to the positive electrode. Therefore, when the separator between the electrode body and the inner wall of the negative electrode can is melted, the negative electrode can and the positive electrode come into contact with each other, and a short circuit occurs, and the separator that wraps the electrode body due to heat generation due to the short circuit is melted. In this case, since other parts of the positive electrode also come into contact with the negative electrode can, a secondary internal short circuit may occur. Further, when a foreign substance is mixed between the electrode body having a winding structure and the negative electrode can, the electrode is brought into a conductive state, which easily causes a micro short circuit, which is likely to be a factor in inducing the micro short circuit during the crush test.

In general, the lead body of the negative electrode and the coating film containing the active material have high resistance. Therefore, when the lead body breaks through the separator and a large current flows due to an internal short circuit in the crushing test, the lead body faces the negative electrode lead body. The positive electrode active material-containing coating film promotes heat generation inside the battery due to Joule heat and hinders heat dissipation, so that the positive electrode easily reaches thermal runaway temperature at a relatively early stage. Furthermore, when a large current is forced to flow by the nail penetration test, the current concentrates on the negative electrode lead body and locally becomes high temperature, and the separator in contact with the lead body is easily softened and melted. Also, the lead body easily breaks through the separator.

In the external short-circuit test, it is confirmed that the battery has a high level of safety by connecting the positive electrode and the negative electrode to make an external short-circuit by setting the charging voltage to a high voltage that cannot be normally used. However, when charged to such a high voltage, the separator around the negative lead body melts parabolically around the lead body and from the outer peripheral side due to the heat generated by the resistance of the lead body. It has been found. That is, when a large current flows due to an external short circuit in the electrode body having a winding structure in which the lead body of the negative electrode is provided in the outermost peripheral portion of the negative electrode, first, the separator on the outer peripheral side of the lead body of the negative electrode is violently melted, and then, The separator on the inner peripheral side of the negative electrode lead body is melted. In particular, the separator on the inner peripheral side of the lead body of the negative electrode is melted and destroyed over the inner peripheral side two or three layers of the wound electrode body in proportion to the increase in the energy density of the battery. Then, when the positive electrode active material-containing coating film and the negative electrode active material-containing coating film are melted up to the part where the separator is faced and destroyed, an internal short circuit occurs due to contact between the positive electrode active material-containing coating film and the negative electrode active material-containing coating film. The raised battery causes abnormal heat generation. When a secondary internal short-circuit from such an external short-circuit test occurs, a large current flows as in the case of the crush test and the positive electrode active material-containing coating facing the negative electrode lead body has a joule. Since the heat promotes heat generation inside the battery and hinders heat dissipation, the positive electrode easily reaches the thermal runaway temperature at a relatively early stage. Further, similar to the crushing test, when both the positive electrode and the negative electrode are present in the outermost peripheral portion of the electrode body having the wound structure, the melting of the separator on the outer peripheral surface side of the negative electrode lead body proceeds, and the space between the positive electrode and the negative electrode can is increased. When the separator of No. 1 is melted, the negative electrode can and the positive electrode come into contact with each other, and a short circuit occurs,
When foreign matter is mixed between the electrode body and the negative electrode can during an external short circuit, particularly when the resistance of the foreign matter is high, current concentrates on this short-circuited portion, and local heat generation becomes large.

The present invention takes the above circumstances into consideration,
Since the electrode of the spirally wound electrode body that faces the negative electrode can is composed substantially of the negative electrode, and the negative electrode lead body does not directly face the positive electrode through the separator, the outermost circumference is prone to cause an internal short circuit. In addition to reducing the probability of occurrence of short circuit in the part, it is possible to prevent local heat generation due to foreign matter mixed in, and even if the battery of the present invention is forcibly crushed by a crush test, an internal short circuit due to the lead body is unlikely to occur, Further, even when a large current flows through the lead body of the negative electrode to generate heat due to the external short-circuit test, it is possible to suppress melting of the separator and reduce heat generation. In the present invention, as described above, the electrode facing the negative electrode can of the electrode body having the winding structure is substantially composed of the negative electrode, but the above-mentioned substantially negative electrode naturally includes the case of only the negative electrode. However, the finish accuracy of the wound electrode body may be slightly affected by the accuracy of the winding machine, etc. Not only that, but also the case where the positive electrode is partially mixed occurs, so even if the positive electrode is partially mixed as long as it is within a range that does not affect the reduction of the occurrence of the internal short circuit, It means that it is included in the category of negative electrode. Further, the negative electrode in the above may be only the negative electrode current collector on which the active material-containing coating film is not formed.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below.

According to a specific embodiment of the present invention, as shown in FIG. 2, the positive electrode active material-containing coating film is not formed on the outer peripheral surface side of the positive electrode current collector 1a at the outermost peripheral portion of the positive electrode 1, The positive electrode active material-containing coating film 1b is formed only on the peripheral surface side (note that although not shown in FIG. 2, the inner peripheral side 2 when viewed from the outermost peripheral portion of the positive electrode 2).
A positive electrode active material-containing coating film is formed on both surfaces of the positive electrode current collector on the positive electrode after the first cycle). In addition, the electrode of the spirally wound electrode body facing the negative electrode can is substantially composed of the negative electrode (however, in FIG. 2 and FIGS. Only the periphery of the lead body is shown for avoidance), and the negative electrode 2 is shown at the outermost peripheral portion and the second circumference from the outermost peripheral portion, but the outermost peripheral portion of the negative electrode 2 is only the negative electrode current collector 2a. The negative electrode active material-containing coating film was not formed on any of the surfaces, and
On the second cycle, the negative electrode active material-containing coating film 2 is formed on both surfaces of the negative electrode current collector 2a.
b is formed. The separator 3 is interposed not only between the positive electrode 1 and the negative electrode 2 but also between the negative electrode current collector 2 a located at the outermost peripheral portion of the electrode body having the winding structure and the inner surface of the negative electrode can 5. . It should be noted that the drawings including the electrode body having the winding structure, including FIG. 2, each schematically show the electrode body having the winding structure, and the dimensional ratio of each member is not necessarily accurate. This is because, in reality, a member having a small thickness is illustrated with a certain thickness. In addition, due to such a relationship, it is illustrated that there are actually no gaps as if there are gaps, and vice versa, and where there are actually only small gaps, there is a large gap. There are parts that are illustrated as if they are open.

In the spirally wound electrode body of this specific form, as shown in FIG. 2, the electrode of the spirally wound electrode body facing the negative electrode can 5 is substantially composed of the negative electrode 2, and the positive electrode The positive electrode active material-containing coating film is not formed on the outer peripheral surface side of the positive electrode current collector 1a at the outermost peripheral portion of 1, and the exposed portion of the positive electrode current collector 1a (that is, the positive electrode active material of the positive electrode current collector 1a is The portion where the substance-containing coating film is not formed) is the exposed portion of the negative electrode current collector 2a of the negative electrode 2 through the separator 3 (that is, the portion where the negative electrode active material-containing coating film of the negative electrode current collector 2a is not formed). And the lead body 15 welded to the negative electrode current collector 2a of the negative electrode 2 faces the negative electrode active material-containing coating film 2b of the second negative electrode 2 from the outermost peripheral portion through the separator 3 to form the positive electrode 1. Do not face each other directly.

Therefore, in the battery having the spirally wound electrode body of this specific form, the chargeable / dischargeable capacity at full charge is 130 mAh / cm ³ per unit volume of the spirally wound electrode body.
Even in the case of the above high capacity, when the nail is pierced in the portion where the negative electrode current collector 2a at the outermost peripheral portion of the electrode body faces the positive electrode current collector 1a through the separator 3 in the nail puncture test, Heat is dispersed, the positive electrode 1 is less likely to reach the thermal runaway temperature, the battery is less likely to generate abnormal heat, and safety can be improved. Further, even in the crush test, stress is less likely to be applied to the lead body 15 portion of the negative electrode 2, so that it is possible to prevent an internal short circuit during the crush test, and even when crushed, the lead body 15 of the negative electrode 2 is seen from the outermost peripheral portion. Since it comes into contact with the negative electrode 2 in the second round, the occurrence of an internal short circuit can be prevented. Furthermore, since the electrode facing the negative electrode can 5 of the wound electrode body is substantially composed of only the negative electrode 2, the negative electrode can 5 also serving as the negative electrode terminal and the positive electrode 1 face each other via the negative electrode 2. Even if the separator 3 interposed between the electrode body having the winding structure and the negative electrode can 5 is melted or broken by the crush test or the external short circuit test, the positive electrode 1
Does not cause an internal short circuit due to contact between the negative electrode can 5 and the negative electrode can 5, and it is difficult for a minute short circuit due to foreign substances mixed between the wound electrode body and the negative electrode can 5 to occur. The probability of progress can be reduced, and in the external short-circuit test, since the positive electrode 1 does not exist in the electrode facing the negative electrode can 5, it is possible to prevent the conductive state, and avoid local heat generation. it can. Even when a large current flows through the lead body 15 due to a nail piercing test, a crush test, an external short-circuit test, etc., and the lead body 15 generates heat and the separator 3 melts, the lead body 15 does not face the positive electrode 1. It is possible to prevent the occurrence of internal short circuit.

In particular, when the shape of the wound electrode body is elliptical or elliptical, the convex portions of the lead body 15 tend to give torsional stress or strain stress, thereby contacting the lead body 15. Since the stress applied to the separator 3 increases, the separator 3 is more likely to melt when the lead body 15 generates heat. However, according to the present invention, safety can be ensured even in such a case. When applied in such a case, the effect can be remarkably exhibited. It is preferable that the outermost peripheral portion corresponds to one outermost peripheral portion of the electrode as described later in a specific form. However, if the probability that an internal short circuit occurs can be reduced, the outermost peripheral portion should be less than one peripheral portion. It may be applicable.

In addition, in the present invention, the above-mentioned wound electrode body is used, and the positive electrode active material-containing coating film 1b of the positive electrode 1 is formed in the separator 3 in the longitudinal direction of the wound electrode body.
The portion facing the negative electrode active material-containing coating film 2b of the negative electrode 2 with the positive electrode current collector 1a not forming the positive electrode active material-containing coating film 1b at the outermost peripheral portion of the positive electrode 1 is substantially disposed on the outer peripheral surface side. It is necessary to provide at least one round. That is, by providing the positive electrode current collector 1a with a portion where the positive electrode active material-containing coating film is not formed at least once in the outermost peripheral portion of the positive electrode 1, no matter where the electrode body is nailed, Although it is possible to reduce the probability of abnormal heat generation, when the portion where the positive electrode active material-containing coating film 1b is not formed is substantially less than one turn, the probability of abnormal heat generation when nailing is determined. It cannot be reduced sufficiently.

In the present invention, as one of the forms, when the electrode body having the above-mentioned winding structure is used, the thickness of the negative electrode 2 at the portion where the thickness of the lead body 15 welded to the negative electrode current collector 2a is opposite. And the triple thickness of the separator 3 (thickness of the negative electrode 2 + thickness of the separator 3 × 3). That is, in the crush test, when the lead body 15 of the negative electrode 2 is pressed toward the inner peripheral side, the lead body 1 of the negative electrode 2 is
By making the thickness of 5 smaller than the total thickness of the thickness of the negative electrode 2 and the thickness of the separator 3, the crushing progresses and the lead body 15 pierces the negative electrode 2 on the second lap when viewed from the outermost periphery, and The occurrence of internal short circuit due to contact with the positive electrode 1 on the inner peripheral side can be reduced.

As is apparent from the above description, the thickness of the negative electrode 2 referred to here is from the viewpoint of preventing an internal short circuit due to the lead body 15 of the negative electrode 2 breaking through the facing negative electrode 2. 2 means the thickness of the negative electrode 2 on the inner peripheral side facing the second lead body 15.

Further, in still another embodiment of the present invention, the start of the overlap between the positive electrode active material-containing coating film 1b and the negative electrode active material-containing coating film 2b at the outermost peripheral portion of the wound electrode body. The distance between the portion 17 and the lead body 15 of the negative electrode 2 (refers to the distance between the portions closest to each other. The same applies hereinafter).
1 for one turn of the negative electrode at the outermost periphery of the wound electrode body
/ 6 or more laps and 1/2 or less laps apart. That is, in the external short-circuit test, as described above, the separator on the inner peripheral side of the lead body 15 of the negative electrode 2 is in proportion to the increase in the energy density of the battery, the inner peripheral side 2, 3 of the electrode body having the winding structure. The layers 3 are melted and destroyed, and the separator 3 around the lead body 15 of the negative electrode 2 at the outermost periphery is the lead body 15 of the negative electrode 2.
Since it melts in a parabolic shape centering around, the overlapping start portion 17 of the positive electrode active material-containing coating film 1b and the negative electrode active material-containing coating film 2b and the lead body 15 of the negative electrode 2 are separated by a certain distance or more. If not maintained, a secondary internal short circuit may occur when an external short circuit occurs. According to the study by the present inventors, in order to reduce such a secondary internal resistance, the overlapping start portion of the positive electrode active material-containing coating film 1b and the negative electrode active material-containing coating film 2b in the outermost peripheral portion. It has been found that the distance between 17 and the lead body 15 of the negative electrode 2 needs to be set at a distance of 1/6 or more and 1/2 or less with respect to 1 round of the outermost peripheral portion of the negative electrode 2, and particularly 1 It has also been found that it is preferable to install them at a distance of / 5 or more and 1/2 or less.

Further, in the present invention, when the electrode body having the above-mentioned winding structure is used, the negative electrode 2 is provided as shown in FIG. 2 so that the outermost peripheral portion of the negative electrode 2 can smoothly radiate heat.
It is preferable to have a structure in which the negative electrode active material-containing coating film is not formed on both surfaces of the negative electrode current collector 2a in the outermost peripheral portion.

As shown in FIG. 2, in the outermost peripheral portion of the positive electrode 1, the positive electrode active material-containing coating film is not formed on the outer peripheral surface side of the positive electrode current collector 1a. By forming the positive electrode active material-containing coating film only on the peripheral surface side, the thickness of the positive electrode active material-containing coating film and the negative electrode active material-containing coating film that are not charged / discharged can be reduced and the space inside the negative electrode can can be efficiently used. Therefore, the capacity can be further increased. By applying the present invention even to such a high capacity battery, the safety can be greatly improved.

In order to further reduce the probability of occurrence of internal short circuit, the above-mentioned wound electrode body has a concrete form as shown in FIG. It is preferable to provide substantially one or more round portions on both surfaces of the body 2a on which the negative electrode active material-containing coating film is not formed, and at the outermost peripheral portion of the positive electrode 1, the positive electrode current collector 1a.
It is necessary to substantially provide one or more round portions on the outer peripheral surface side where the positive electrode active material-containing coating film is not formed.

That is, in this specific embodiment, as shown in FIG. 5, the electrode facing the negative electrode can 5 of the spirally wound electrode body is constituted by only the negative electrode 2 for at least one turn.
Although the negative electrode 2 is shown at the outermost peripheral portion and the second circumference from the outermost peripheral portion, one or more circumferences of the outermost peripheral portion of the negative electrode 2 is only the negative electrode current collector 2a, and the negative electrode active material is provided on any surface thereof. The contained coating film is not formed, and the negative electrode active material-containing coating film 2b is formed on both surfaces of the negative electrode current collector 2a after the second lap from the outermost peripheral portion. This positive electrode 1 is also the outermost peripheral portion and 2 from the outermost peripheral portion.
Although the circumference is shown, the positive electrode current collector 1 is provided at the outermost periphery.
The positive electrode active material-containing coating film is not formed on the outer peripheral surface side of a, and the exposed portion of the positive electrode current collector 1a is provided for one or more rounds. The exposed portion of the positive electrode current collector 1a is separated by the separator 3. It faces the exposed portion of the negative electrode current collector 2 a of the negative electrode 2. Also,
The lead body 15 welded to the negative electrode current collector 2a of the negative electrode 2 faces the negative electrode current collector 2a of the negative electrode 2 on the second lap from the outermost peripheral portion via the separator 3 as in the case of the specific embodiment. , Does not directly face the positive electrode 1.

Therefore, in the battery having the winding structure electrode body of this specific form, the negative electrode 5 facing the negative electrode can 5 of the winding structure electrode body is used as the negative electrode, as in the case of the specific form. And an effect based on a structure in which the lead body 15 of the negative electrode does not directly face the positive electrode 1, and the positive electrode 1,
Both the negative electrode 2 and the negative electrode current collector 2a having a low resistance and the positive electrode current collector 1a are short-circuited at any position since there is no portion facing the active material-containing coating having a high resistance over one or more rounds of the outermost peripheral portion. Therefore, heat generation due to an internal short circuit can be further reduced. Even when foreign matter is mixed between the outermost periphery of the wound electrode body and the negative electrode can 5, the positive electrode 1 and the negative electrode 2 face each other only with the current collector, so that a micro short circuit occurs. Even in the case, the resistance is small and the possibility of an internal short circuit can be reduced. Furthermore, even if a short circuit occurs, since the current collectors made of metal are in contact with each other, their high thermal conductivity promotes heat dissipation, so that the battery does not easily generate abnormal heat in the entire outermost peripheral portion. .

In the specific embodiment of the present invention, as opposed to providing the negative electrode lead body 15 on the inner peripheral surface side of the outermost peripheral portion of the negative electrode 2 in the specific embodiment, as shown in FIG. The lead body 15 is provided on the outer peripheral surface side of the outermost peripheral portion.
That is, in the outermost peripheral portion of the electrode having the winding structure, the positive electrode active material-containing coating film is not formed on the outer peripheral surface side of the positive electrode current collector 1a, and the positive electrode active material-containing coating film 1b is formed only on the inner peripheral surface side. is doing. Further, in FIG. 4, the negative electrode 2 is shown at the outermost peripheral portion and the second circumference from the outermost peripheral portion. However, at the outermost peripheral portion of the negative electrode 2, only the negative electrode current collector 2a is provided, and any surface thereof is The negative electrode active material-containing coating film is not formed, and the negative electrode active material-containing coating film 2b is formed on both surfaces of the negative electrode current collector 2a in the second round from the outermost peripheral portion.
Are formed. Then, in this specific form, the lead body 15 of the negative electrode 2 is attached to the outer peripheral surface side of the tip end portion of the negative electrode current collector 2a at the outermost peripheral portion, and the separator 3 is provided not only between the positive electrode 1 and the negative electrode 2. It is also interposed between the negative electrode current collector 2 a located at the outermost peripheral portion of the wound electrode body and the inner peripheral surface of the negative electrode can 5.

In the spirally wound electrode body of this specific form, as shown in FIG. 4, the electrode of the spirally wound electrode body facing the negative electrode can 5 is substantially composed of the negative electrode 2, and the positive electrode No positive electrode active material-containing coating film is formed on the outer peripheral surface side of the positive electrode current collector 1a at the outermost peripheral portion of 1, and the positive electrode active material-containing coating film 1b is formed only on the inner peripheral surface side. The exposed portion of the body 1a faces the exposed portion of the negative electrode current collector 2a of the negative electrode 2 via the separator 3, and the lead body 15 welded to the negative electrode current collector 2a of the negative electrode 2 has the negative electrode can 5 via the separator 3. The positive electrode 1 and the positive electrode 1 do not directly face each other.

Therefore, in the battery having the winding structure electrode body of this specific form, the chargeable / dischargeable capacity at full charge is 130 mAh / cm 3 per unit volume of the winding structure electrode body.
Even if the capacity is as high as ³ or more, when the nail is pierced in the nail piercing test, local heat is dispersed, the positive electrode does not easily reach the thermal runaway temperature, the battery does not easily generate abnormal heat, and it is safe. It is possible to improve the sex. Also in the crush test, since the lead body 15 of the negative electrode 2 faces the negative electrode can 5, even when crushed, the lead body 15 of the negative electrode 15
Is only in contact with the negative electrode can 5, so that an internal short circuit can be prevented. Furthermore, since the electrode facing the negative electrode can 5 of the spirally wound electrode body is substantially only the negative electrode, the negative electrode can 5 also serving as the negative electrode terminal and the positive electrode 1 face each other through the negative electrode 2 and thus collapse. Even if the separator 3 around the negative electrode lead body 15 facing the negative electrode can is melted or broken by a test or an external short-circuit test, the positive electrode 1 and the negative electrode can 5 do not come into contact with each other, and a foreign substance between the negative electrode can 5 is present. Is less likely to occur, and the probability of progressing to an internal short circuit during a crush test can be reduced, and since the positive electrode 1 does not exist on the electrode facing the negative electrode can 5 in the external short circuit test,
It is possible to prevent a conductive state and to avoid local heat generation. Then, even when a large current flows through the lead body 15 of the negative electrode 2 by the nail penetration test, the crushing test, and the external short-circuiting test, and the lead body 15 generates heat to melt the separator 3, the lead body 15 directly faces the positive electrode 1. Since it does not, it is possible to prevent the occurrence of an internal short circuit.

In the spirally wound electrode body of the specific embodiment of the present invention, as shown in FIG. 3, an electrode facing the negative electrode can 5 of the spirally wound electrode body, as in the case of the aforementioned specific embodiment. Are substantially composed of the negative electrode 2, and the positive electrode current collector 1a
Of the positive electrode active material-containing coating film is formed on the inner peripheral surface side of the positive electrode active material-containing coating film 1b. An insulating tape 16 is adhered, and the positive electrode insulating tape 16 faces the lead body 15 welded to the negative electrode current collector 2a via the separator 3, and the lead body 15 of the negative electrode 2 does not directly face the positive electrode 1. There is.

Therefore, also in the battery having the electrode body having the winding structure of this specific form, it is difficult for the positive electrode to reach the thermal runaway temperature in the nail penetration test and the crushing test, and the battery is unlikely to generate abnormal heat, which is safe. It is possible to improve the sex. Also in the crush test, even when stress is applied to the lead body 15 of the negative electrode 2 to break through the separator 3 and approach the positive electrode 1, the positive electrode insulating tape 16 facing the lead body 15 prevents direct contact with the positive electrode 1. It is possible to prevent the occurrence of internal short circuit. Further, as in the case of the specific embodiment, the electrode facing the negative electrode can 5 of the wound electrode body is substantially the negative electrode 2, so that the inside of the wound electrode body at the outermost periphery is When the occurrence of short circuit can be reduced and a large current flows in the lead body 15 of the negative electrode 2 in the nail penetration test, the crush test, the external short circuit test, etc. and the lead body 15 locally becomes high temperature and the separator 3 is softened and melted However, the lead body 15 of the negative electrode 2 has the separator 3
Since it only contacts with the positive electrode insulating tape 16 which faces through via, the occurrence of an internal short circuit can be prevented.

Further, in the present invention, in the electrode body having the above winding structure, the lead body 1 welded to the negative electrode current collector 2a.
5, the total thickness of the thickness of the positive electrode insulating tape 16 and the thickness of the separator 3 at the portions facing each other (the positive electrode insulating tape 16
(Thickness + thickness of separator 3). That is, in the crush test for the above-described wound electrode body, the lead body 15 of the negative electrode 2 is made thinner than the total thickness of the positive electrode insulating tape 16 and the separator 3 in the crush test. It is possible to reduce the occurrence of internal short circuit due to the crushing progressing, the lead body 15 breaks through the separator 3 and comes into contact with the positive electrode 1 on the inner peripheral side when is pressed to the inner peripheral side.

Also, in the battery having the winding structure electrode body of any of the above specific forms, as described in the above specific form, the negative electrode of the winding structure electrode body facing the negative electrode can 5 is collected. Without providing active material-containing coating on both sides of the body,
It is also possible to provide the active material-containing coating film on the positive electrode only on the inner peripheral surface side and to provide the exposed portion of the current collector on the outer peripheral surface side for one or more rounds.
With such a structure, it is possible to have a structure in which the current collectors face each other at least once in the outermost peripheral portion of the electrode body having the winding structure only for one or more rounds. It is possible to prevent a large current from flowing due to the contact, and it is possible to reduce the amount of heat generation even on the inner peripheral side at the time of an internal short circuit. Further, also in the above specific modes, similarly to the case of the specific modes, in order to prevent a secondary internal short circuit in the external short circuit test, the positive electrode active material containing in the outermost peripheral portion of the electrode body of the winding structure. The overlapping start portion 17 of the coating film 1b and the coating film 2b containing the negative electrode active material and the lead body 15 of the negative electrode 2 are arranged at a distance of 1/6 or more with respect to one round of the negative electrode at the outermost peripheral portion. preferable.

In addition, in the above-mentioned specific modes,
In the nail penetration test, the crushing test, the external short-circuit test, etc., heat dissipation during an internal short-circuit becomes easier. As shown, if the lead body 15 of the negative electrode 2 does not directly face the positive electrode 1, the lead body 15 of the negative electrode 2 can be provided inside the electrode body.

Next, the battery structure of the present invention will be described.

In the non-aqueous secondary battery of the present invention, the electrolyte may be any of an organic solvent liquid electrolyte, a gel electrolyte and a solid electrolyte, but the present invention is a liquid electrolyte (hereinafter referred to as "electrolyte solution"). Is particularly effective when used. As a solvent of the electrolytic solution, a chain ester having a chain COO-bond such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and methyl propionate, or propylene carbonate (P
C), ethylene carbonate (EC), butylene carbonate (BC), gamma-butyrolactone (γ-B
L), cyclic esters such as ethylene glycol sulfite (EGS), and 1,2-dimethoxyethane (D
ME), 1,3-dioxolane (DO), tetrahydrofuran (THF), 2-methyl-tetrahydrofuran (2Me-THF), ethers such as diethyl ether (DEE), amine-based or imide-based organic solvents, and sulfur-containing sulfur. A system-based, fluorine-containing, phosphoric acid-containing, or silicon-containing organic solvent can also be used.

In the present invention, it is preferable to use a chain ester as the main solvent of the solvent in the above-mentioned electrolytic solution because it lowers the viscosity of the electrolytic solution and increases the ionic conductivity. The main solvent means that the chain ester exceeds 50% by volume in the total electrolyte solvent containing these chain esters. When the chain ester exceeds 65% by volume, the safety of the battery in the nail penetration test after charging 4.4 V tends to decrease in the prior art. However, according to the present invention, such chain ester is Even when it exceeds 65% by volume, safety can be secured and the effect of the present invention is remarkably exhibited.

When the chain ester exceeds 70% by volume, the safety of the battery is more likely to be lowered in the prior art, so that the effect of the present invention is more remarkably exhibited, and the chain ester is When it exceeds 75% by volume, the safety of the battery is likely to be further lowered in the conventional technique, so that the effect of the present invention is more remarkably exhibited. Further, even if the chain ester has a methyl group, the safety of the battery was likely to be lowered in the prior art, but according to the present invention, the safety can be ensured even when such a chain ester has a methyl group. The effect of the present invention is more remarkably exhibited.

When the following ester having a high dielectric constant (dielectric constant of 30 or more) is mixed and used,
Since the cycle characteristics and the load characteristics of the battery are improved as compared with the case where only the chain ester is used, it is more preferable as a battery. Examples of such an ester having a high dielectric constant include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (B
C), gamma-butyrolactone (γ-BL), ethylene glycol sulfite (EGS) and the like.
In particular, those having a cyclic structure are preferable, cyclic carbonates are particularly preferable, and ethylene carbonate (EC) is most preferable.

The above-mentioned high dielectric constant ester is preferably less than 40% by volume, more preferably 30% by volume or less, further preferably 25% by volume or less in the total solvent of the electrolytic solution. Further, the improvement of safety by the ester having a high dielectric constant seems to be improved when the above ester is 10% by volume or more in the entire solvent of the electrolytic solution, and further improved when it reaches 20% by volume. become.

As the solute of the electrolytic solution, for example, LiCl
O_Four, LiPF₆, LiBF_Four, LiAsF₆, LiS
bF₆, LiCF₃SO₃, LiC_FourF₉SO₃, Li
CF ₃CO₂, Li₂C₂F_Four(SO₃)₂, LiN
(CF₃SO₂)₂, LiC (CF₃SO₂)₃, Li
C_nF_{2n + 1}SO₃(N ≧ 2), LiN (RfOSO₂)
₂[Where Rf is a fluoroalkyl group], etc.
Or a mixture of two or more kinds, especially LiPF₆Or
LiC_FourF₉SO₃Etc. have good charge and discharge characteristics
preferable. The concentration of solute in the electrolyte is not particularly limited.
It is not limited to 0.3 to 1.7 mol / l, especially
It is preferably about 0.4 to 1.5 mol / l.

In the present invention, the positive electrode active material is not particularly limited, but examples thereof include lithium cobalt oxide such as LiCoO ₂ , lithium manganese oxide such as LiMn ₂ O _4, and lithium nickel such as LiNiO _2. Metal oxides such as oxides, manganese dioxide, vanadium pentoxide, and chromium oxides, or complex oxides having these as basic structures (for example, different metal additive products), or metal sulfides such as titanium disulfide and molybdenum disulfide. Are used. Especially LiNiO ₂ , LiCoO ₂ , LiM
It is preferable to use, as the positive electrode active material, a lithium composite oxide such as n ₂ O _{4 which} has an open circuit voltage at the time of charging of 4 V or more on the basis of Li, since a high energy density can be obtained. Particularly, charged LiCoO ₂ and LiNiO ₂ have a lower reaction initiation temperature with an electrolytic solution than LiMn ₂ O ₄ and the positive electrode easily reaches a thermal runaway temperature due to heat generation of the negative electrode. However, according to the present invention, LiCoO 2 as a positive electrode active material is used. _Since safety can be ensured even when ₂ or LiNiO ₂ is used, the present invention uses LiCoO ₂ or LiNiO ₂ as the positive electrode active material.
When using, the effect is remarkably exhibited.

For the positive electrode, for example, a conductive auxiliary agent such as scaly graphite or carbon black or a binder such as polyvinylidene fluoride or polytetrafluoroethylene is appropriately added to the above positive electrode active material, A positive electrode current collector made of a paste with a solvent (the binder may be dissolved in the solvent in advance and then mixed with the positive electrode active material), and the positive electrode active material-containing paste is made of a metal foil such as an aluminum foil. It is prepared by applying the composition to a substrate and drying to form a coating film containing a positive electrode active material. However, in the present invention, as described above, in the electrode body having the wound structure, the positive electrode active material-containing coating film is not formed on at least the outermost peripheral portion of the positive electrode on the outer peripheral surface side of the positive electrode current collector. Leave only the electric part.

In the present invention, the thickness of the positive electrode current collector is preferably 5 to 60 μm, particularly preferably 8 to 40 μm.
Further, the thickness of the coating film containing the positive electrode active material is preferably 30 to 300 μm, and particularly preferably 50 to 150 μm per one surface.

The material used for the negative electrode may be any material that can be doped with lithium ions and dedoped. In the present invention, such a material that can be doped with lithium ions and dedoped can be referred to as a negative electrode active material. The negative electrode active material is not particularly limited, and examples thereof include graphite, pyrolytic carbons, cokes, glassy carbons, organic polymer compound fired bodies, mesocarbon microbeads, and carbon fibers. , Carbon materials such as activated carbon, Si, S
An alloy such as n or In, or an oxide such as Si, Sn, or In that can be charged and discharged at a low voltage close to Li can be used.

When a carbon material is used as the negative electrode active material,
The carbon material preferably has the following characteristics.
That is, the inter-plane distance (d ₀₀₂ ) of the (002) plane is preferably 3.5 Å or less, and more preferably 3.
It is 45 Å or less, more preferably 3.4 Å or less. Further, regarding the crystallite size (Lc) in the c-axis direction, it is 3
It is preferably 0 Å or more, more preferably 80 Å or more, and further preferably 250 Å or more. The average particle size of the carbon material is preferably 8 to 20 μm, more preferably 10 to 15 μm, and the purity is preferably 99.9% by weight or more.

For the negative electrode, for example, a binder such as polyvinylidene fluoride or polytetrafluoroethylene is appropriately added to the above-mentioned negative electrode active material, and if necessary, a conductive auxiliary agent is appropriately added to form a paste with a solvent. (The binder may be dissolved in a solvent in advance and then mixed with the negative electrode active material, etc.), and the negative electrode active material-containing paste is applied to a negative electrode current collector made of copper foil or the like and dried to form a negative electrode. It is prepared by forming a coating film containing an active material. However, in the present invention, a negative electrode active material-containing coating film is formed on at least the outermost peripheral portion of the negative electrode on the outer peripheral surface side of the negative electrode current collector in the electrode body having a wound structure as shown in Examples described later. Without
It is preferable to leave only the negative electrode current collector.

In the present invention, the thickness of the negative electrode current collector is preferably 5 to 60 μm, particularly preferably 8 to 40 μm.
The thickness of the coating film containing the negative electrode active material is preferably 30 to 300 μm, and particularly preferably 50 to 150 μm per one surface.

As the positive electrode current collector and the negative electrode current collector, for example, metal foils such as aluminum, copper, nickel and stainless steel, expanded metals, nets and the like are used, and the positive electrode current collector is particularly aluminum. A foil is preferable, and a copper foil is particularly preferable as the negative electrode current collector.

In producing the positive electrode or the negative electrode, as a coating method for applying the positive electrode active material-containing paste or the negative electrode active material-containing paste to the current collector, for example, an extrusion coater, a reverse roller, a doctor blade or the like can be used. Various coating methods can be adopted.

From the viewpoint of increasing the capacity,
It is preferable that the chargeable / dischargeable capacity per unit volume of the wound electrode is large, and the chargeable / dischargeable capacity at full charge is 130 mAh / cm ³ per unit volume of the wound electrode.
The above is preferable, 140 mAh / cm ³ or more is more preferable, and 150 mAh / cm ³ is further preferable. Such a high-capacity battery is prone to abnormal heat generation, but the present invention can ensure safety even for a high-capacity battery as described above. The effect is remarkably exhibited when applied to a battery having a capacity.

In the present invention, the negative electrode lead body is welded to the negative electrode produced as described above on the exposed portion of the negative electrode current collector by resistance welding, ultrasonic welding or the like. The cross-sectional area of 0.1 mm ² in order to reduce the resistance and heat generation when a large current flows.
It is preferably 1.0 mm ² or less, more preferably 0.3 mm ² or more and 0.7 mm ² or less. Nickel is generally used as the material of the lead body of the negative electrode, but copper, titanium, stainless steel and the like can also be used.

In the present invention, it is preferable to use, for example, an imide-based, polytetrafluoroethylene-based, or polyphenylene sulphite-based insulating tape as the positive electrode insulating tape adhered to the positive electrode current collector. The thickness of the positive electrode insulating tape is 120 μm when the thickness is 50 μm or more.
m or less is preferable, and 60 μm or more and 100 μm or less is more preferable. The width of the positive electrode insulating tape depends on the width of the opposing lead body (negative electrode lead body), but is usually preferably 5 mm or more and 15 mm or less, and more preferably 7 mm or more and 12 mm or less.

In the present invention, a separator having sufficient strength and capable of holding a large amount of electrolytic solution is preferable. From such a viewpoint, polypropylene having a thickness of 10 to 50 μm and a porosity of 30 to 70% is preferable. Made from polyethylene, polyethylene or a copolymer of ethylene and propylene are preferable.

In the non-aqueous secondary battery of the present invention, for example, a separator is interposed between the positive electrode and the negative electrode manufactured as described above, and they are stacked, and the spiral shape, the elliptical shape, the oval shape, etc. It is manufactured through a process of inserting the electrode body having the wound structure manufactured by winding into a negative electrode can made of nickel-plated iron, stainless steel, aluminum or aluminum alloy, and sealing. In addition, an explosion-proof mechanism for preventing the battery from bursting under high pressure by discharging the gas generated inside the battery to the outside of the battery when the gas has risen to a certain constant pressure is usually incorporated in the battery.

The non-aqueous secondary battery targeted by the present invention tends to increase the risk of abnormal heat generation, etc., when it is charged to a charging voltage of 4.25 V or higher, particularly 4.35 V. According to the present invention, safety can be ensured even in such a case. Therefore, when the present invention is applied to such a case, the effect is remarkably exhibited. The details will be described in Examples.

The present invention can be applied regardless of the shape of the battery, and can be applied to batteries of any shape, but is particularly suitable for batteries of cylindrical shape, elliptic cylinder shape, prismatic shape and the like. ing. Then, in the discharged state of the battery, the minimum value of the winding outer diameter of the electrode body having the winding structure is 0.4 to 0.7 from the inner diameter of the negative electrode can of the cylindrical battery or the elliptic cylindrical battery as described above.
It is preferable to reduce the size by mm. That is, by setting the minimum value of the outer diameter of the wound electrode body of the wound structure to be 0.4 mm or more smaller than the inner diameter of the negative electrode can in the discharged state of the battery, even when the battery capacity becomes high, it is The safety can be surely secured, and the capacity of the battery can be greatly reduced by making the minimum value of the outer diameter of the wound electrode body of the wound structure 0.7 mm smaller than the inner diameter of the negative electrode can in the discharged state of the battery. Can be prevented. The method for measuring the winding outer diameter of the electrode having the winding structure will be described in detail in Examples below.

[0071]

EXAMPLES Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to only those examples.

Example 1 LiPF ₆ was added to a mixed solvent prepared by mixing methyl ethyl carbonate and ethylene carbonate in a volume ratio of 2: 1.
Dissolve 2 mol / l, composition is 1.2 mol / l Li
An electrolytic solution represented by PF ₆ / EC: MEC (1: 2 volume ratio) was prepared.

EC in the above electrolytic solution is an abbreviation for ethylene carbonate, and MEC is an abbreviation for methyl ethyl carbonate. Therefore, 1.2mo indicating the above electrolyte solution
1 / l LiPF ₆ / EC: MEC (1: 2 volume ratio) is
1.2 mol / mL of LiPF ₆ was added to a mixed solvent of methyl ethyl carbonate and ethylene carbonate in a volume ratio of 1: 2.
1 shows that it was dissolved.

Separately, LiC as a positive electrode active material is used.
A weight ratio of scaly graphite as a conductive additive to oO ₂ of 92: 4.
The mixture was added at a ratio of 5 and mixed, and this mixture was mixed with a solution of polyvinylidene fluoride dissolved in N-methylpyrrolidone to prepare a paste. This positive electrode active material-containing paste was passed through a 70-mesh net to remove large ones, and then uniformly applied on both sides of a positive electrode current collector made of an aluminum foil having a thickness of 15 μm and dried to obtain a positive electrode active material-containing coating. A film was formed. However, when the positive electrode made from this is made into an electrode body of a wound structure together with a negative electrode and a separator,
The positive electrode active material-containing paste is not applied to the outermost peripheral portion of the positive electrode on the outer peripheral surface side of the positive electrode current collector, and the uncoated portion (that is, the positive electrode current collector in which the positive electrode active material-containing coating film is not formed) is applied. The length of the exposed part of the body was set to 53 mm (about one lap). This strip was dried, compression-molded to a thickness of 169 μm, cut, and then, one end of a lead body made of aluminum having a width of 3 mm and a thickness of 100 μm was welded to the plain portion (that is, the exposed portion of the positive electrode current collector). A lead body was attached to produce a strip-shaped positive electrode.

Next, a graphite-based carbon material as the negative electrode active material [however, the interplanar distance (d ₀₀₂ ) of 002 planes = 3.37]
Å, a carbon material having a crystallite size in the c-axis direction (Lc) = 950Å, an average particle size of 10 μm, and a purity of 99.9% or more], in which polyvinylidene fluoride is dissolved in N-methylpyrrolidone To prepare a paste. This negative electrode active material-containing paste was uniformly applied to both surfaces of a negative electrode current collector made of a strip-shaped copper foil having a thickness of 10 μm and dried to form a negative electrode active material-containing coating film. However, when a negative electrode made of this is formed into an electrode body having a wound structure together with the positive electrode and the separator, the negative electrode active material-containing paste is not applied to the negative electrode current collector in the outermost peripheral portion of the negative electrode. The length of the uncoated portion (that is, the exposed portion of the negative electrode current collector on which the negative electrode active material-containing coating film was not formed) was set to 48 mm. After this band-shaped body was dried, compression-molded to a thickness of 167 μm and cut, and then, at a width of 3 mm and a thickness of 0.1 mm (cross-sectional area) at a distance of 8 mm from the tip of the plain part (that is, the exposed part of the negative electrode current collector). One end of a 0.3 mm ² ) nickel lead body was welded to produce a strip-shaped negative electrode.

After the positive electrode and the negative electrode are dried, the positive electrode is superposed on the negative electrode via a separator made of a microporous polyethylene film having a thickness of 25 μm in a dry atmosphere, spirally wound and spirally wound. The electrode body was structured. The volume of this wound electrode body was 11.3 cm ³ . After that, the electrode body having this winding structure was inserted into a negative electrode can as described later to prepare a cylindrical nonaqueous secondary battery whose structure is schematically shown in FIG. Further, FIG. 2 shows an outermost peripheral portion of the electrode body having the above-mentioned wound structure and a main portion in the vicinity thereof.

First, the electrode body having the winding structure shown in FIG. 2 will be described first. In FIG. 2, the positive electrode 1 is shown at the outermost peripheral portion. The positive electrode active material-containing coating film is not formed on the outer peripheral surface side of the electric body 1a, and the positive electrode active material-containing coating film 1b is formed only on the inner peripheral surface side. The negative electrode 2 is shown with the outermost peripheral portion and the second circumference from the outermost peripheral portion, and the negative electrode can 5 of the electrode body having the winding structure is shown.
The electrode opposite to is substantially composed of the negative electrode 2, and the outermost peripheral portion thereof has the exposed portion of the negative electrode current collector 2a, and the negative electrode active material-containing coating film is not formed on any of the surfaces, In the second round from the outermost periphery, the negative electrode active material-containing coating film 2b is formed on both surfaces of the negative electrode current collector 2a. The lead body 15 of the negative electrode 2 is attached to the inner peripheral surface side of the negative electrode current collector 2a at the outermost peripheral portion. The separator 3 is composed of the positive electrode 1 and the negative electrode 2
And the inner surface of the negative electrode current collector 2a located at the outermost peripheral portion of the wound electrode body and the inner surface of the negative electrode can 5.

In the battery winding structure electrode body of Example 1, as shown in FIG. 2, a positive electrode active material-containing coating film was formed on the outer peripheral surface side of the positive electrode current collector 1a at the outermost peripheral portion of the positive electrode 1. Not formed, and the positive electrode active material-containing coating film 1b is formed only on the inner peripheral surface side. The exposed portion of the positive electrode current collector 1a faces the exposed portion of the negative electrode current collector 2a of the negative electrode 2 through the separator 3, and the lead body 15 welded to the negative electrode current collector 2a of the negative electrode 2 forms the separator 3 It faces the negative electrode active material-containing coating film 2b of the negative electrode 2 on the second lap from the outermost peripheral portion, and does not directly face the positive electrode 1. The distance between the lead member 15 and the overlapping start portion 17 of the positive electrode active material-containing coating film 1b and the negative electrode active material-containing coating film 2b in the outermost peripheral portion is 1/3 of the outermost peripheral portion of the negative electrode 2 in one revolution. It is arranged so that it is separated from the circumference. However, in FIG. 2, the two are shown close to each other in order to prevent the drawing from becoming too large.

Therefore, in the battery of Example 1, under normal use conditions, the lead body 1 welded to the negative electrode current collector 2a was used.
Internal short circuit based on 5 does not occur. The thickness of the lead body 15 of the negative electrode 2 in this battery is 0.1 mm (100 μm).
m), the thickness of the negative electrode 2 is 167 μm, the thickness of the separator 3 is 25 μm, and the thickness of the lead body 15 welded to the negative electrode current collector 2a is 3 times the thickness of the negative electrode 2 and the thickness of the separator 3. It is thinner than the total thickness (thickness of the negative electrode 2 + thickness of the separator 3 × 3). Therefore, in this battery, even if the battery is forcibly crushed in the crush test, the lead body 15 welded to the negative electrode current collector 2a is used. Does not press the second negative electrode 2 from the outermost peripheral portion, and the negative electrode active material-containing coating film 2b on the inner peripheral side does not break through the separator 3 and come into contact with the positive electrode 1 to cause an internal short circuit. In addition, when a large current flows through the lead body 15 in the nail penetration test, the crushing test, and the external short-circuit test, the lead body 15 becomes hot, the separator 3 around the lead body 15 softens and melts, and the lead body 15 becomes Even when the separator 3 is pierced, it only contacts the negative electrode 2 on the inner peripheral side, so that an internal short circuit does not occur, and furthermore, the positive electrode active material-containing coating film 1b and the negative electrode active material-containing coating film 2b in the outermost peripheral portion are formed. Overlap start part 17 and lead body 15
Since the distance between and is 1/3 of the circumference of the outermost peripheral portion of the negative electrode 2, it is possible to prevent the occurrence of a secondary internal short circuit. Further, since the electrode facing the negative electrode can 5 of the wound electrode body is the negative electrode 2, the negative electrode can 5 also serving as the negative electrode terminal and the positive electrode 1 face each other through the negative electrode 2.
Even if the separator 3 interposed between the electrode body having the winding structure and the negative electrode can 5 is melted or broken by a crushing test or an external short circuit test, an internal short circuit due to contact between the positive electrode 1 and the negative electrode can 5 does not occur, and A minute short circuit due to a foreign substance mixed between the wound electrode body and the negative electrode can 5 is unlikely to occur, and it is possible to reduce the probability of progressing to an internal short circuit during the crushing test, and the negative electrode can 5 during the external short circuit test. Since the positive electrode 1 does not exist in the electrode facing the electrode, it is possible to prevent the electrode from becoming conductive, and it is possible to avoid local heat generation.
In addition, in the electrode body having the wound structure of the battery of Example 1, the positive electrode active material-containing coating film 1b of the positive electrode 1 always faces the negative electrode active material-containing coating film 2b of the negative electrode 2 with the separator 3 interposed therebetween. , High capacity can be obtained.

Next, a non-aqueous secondary battery using this wound electrode body will be described. First, the outline of the manufacturing method will be described with reference to FIG. 1, and the non-aqueous secondary battery is manufactured as follows. That is, the above-mentioned wound electrode body is inserted into a bottomed cylindrical negative electrode can 5 having an outer diameter of 17.87 mm, and the free end of the lead body 15 of the negative electrode 2 is welded to the inner surface of the bottom of the negative electrode can 5 to form a positive electrode. The free end of the lead body of No. 1 is welded to the sealing plate 7, the electrolytic solution 4 is injected into the negative electrode can 5, and the electrolytic solution 4 is sufficiently penetrated into the separator 3 and the like, and then sealed.
Precharging and aging were performed to produce a cylindrical nonaqueous secondary battery whose structure is schematically shown in FIG.

Standard use conditions of this battery (charging at 1700 mA, and after reaching 4.2 V, charging at a low voltage of 4.2 V is carried out for 2 hours.
The discharge capacity per unit volume of the electrode body having the winding structure measured under the condition that the discharge capacity is 138 mAh / cm
³ , which was a high capacity. In addition, this battery 2.75
After discharging up to V at 1700 mA, it was decomposed in a dry box, washed with dimethyl carbonate, wiped and dried, and then the winding outer diameter of the electrode having a winding structure was changed to LS-50407 manufactured by Keyence Corporation.
The minimum value was 16.9 mm, and the difference between the minimum value part and the inner diameter of the negative electrode can was 0.5 m.
It was m.

Here, the schematic structure of this battery will be described with reference to FIG. However, FIG. 1 schematically shows the arrangement of the wound electrode body and other members, and is mainly for explaining the role of other members (members other than the wound electrode body). However, the structure of the electrode body having the winding structure is not necessarily shown accurately, and the accurate structure of the electrode body having the winding structure is as shown in FIG. In the figure, 1 is the band-shaped positive electrode, and 2 is the band-shaped negative electrode. However, in FIG. 1, in order to avoid complication, a metal foil or the like as a current collector used in manufacturing the positive electrode 1 and the negative electrode 2 is not shown. The positive electrode 1 and the negative electrode 2 are spirally wound with the separator 3 interposed therebetween, and are housed in the negative electrode can 5 together with the electrolytic solution 4 as an electrode body having a spiral spiral structure.

The negative electrode can 5 is made of stainless steel and also serves as a negative electrode terminal. An insulator 6 made of polypropylene is placed at the bottom of the negative electrode can 5 prior to the insertion of the spirally wound electrode body. ing. The sealing plate 7 is made of aluminum and has a disk shape. A thin portion 7a is provided in the center of the sealing plate 7, and a pressure introducing port 7b is provided around the thin portion 7a to act the battery internal pressure on the explosion-proof valve 9. A hole is provided.
The projection 9a of the explosion-proof valve 9 is provided on the upper surface of the thin portion 7a.
Are welded to form a welded portion 11. It should be noted that the thin portion 7a provided on the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9
For ease of understanding in the drawings, etc., only the cut surface is shown, and the contour line behind the cut surface is not shown. In addition, the thin portion 7a of the sealing plate 7 and the protruding portion 9 of the explosion-proof valve 9
The welded portion 11 with a is also illustrated in an exaggerated state from the actual state so that it can be easily understood in the drawings.

The terminal plate 8 is made of rolled steel, has a nickel-plated surface, and has a hat-like shape with a brim-shaped peripheral portion. The terminal plate 8 is provided with a gas outlet 8a. . The explosion-proof valve 9 is made of aluminum and has a disk shape, and a protrusion 9a having a tip portion is provided on the power generating element side (lower side in FIG. 1) in the center thereof, and the lower side of the protrusion 9a is As described above, it is welded to the upper surface of the thin portion 7a of the sealing plate 7 to form the welded portion 11. Insulation packing 1
0 is made of polypropylene and has an annular shape and is arranged on the upper surface of the peripheral edge of the sealing plate 7, and the explosion-proof valve 9 is arranged on the upper part thereof to insulate the sealing plate 7 from the explosion-proof valve 9 and The gap between the two is sealed so that the electrolytic solution does not leak from between them. A PTC element 18 is provided between the explosion-proof valve 9 and the terminal plate 8 so as to have an infinite resistance when a large current flows due to an external short circuit or the like and prevent the large current from flowing inside the battery. There is. The annular gasket 12 is made of polypropylene, the lead body 13 is made of aluminum, the sealing plate 7 and the positive electrode 1 are connected to each other, the insulator 14 is arranged on the upper part of the wound electrode body, the negative electrode 2 and the negative electrode can. The bottom of 5 is connected by a lead body 15 made of nickel.

As described above, the insulator 6 is arranged at the bottom of the negative electrode can 5, and the positive electrode 1, the negative electrode 2 and the separator 3 are provided.
The electrode body having a spiral winding structure consisting of, the electrolytic solution 4, the insulator 14 above the electrode body, and the like are accommodated in the negative electrode can 5, and after accommodating them, a portion in the vicinity of the open end of the negative electrode can 5. An annular groove is formed at the bottom of which protrudes inward. Then, in the opening of the negative electrode can 5, the sealing plate 7 and the insulating packing 1 are provided.
0, the explosion-proof valve 9 and other annular gaskets 12 are arranged, the terminal plate 8 is further inserted from above, and the portion beyond the groove of the negative electrode can 5 is tightened inward to open the negative electrode can 5. The department is sealed. However, in assembling the battery as described above, it is preferable to connect the negative electrode 2 and the negative electrode can 5 with the lead body 15 and the positive electrode 1 and the sealing plate 7 with the lead body 13 in advance.

In the battery assembled as described above, the thin portion 7a of the sealing plate 7 and the protruding portion 9a of the explosion-proof valve 9 are used.
Are in contact with each other at the welded portion 11, the peripheral edge of the explosion-proof valve 9 is in contact with the peripheral edge of the terminal plate 8, and the positive electrode 1 and the sealing plate 7 are connected by the lead body 13 on the positive electrode side. And terminal board 8
An electrical connection is obtained by the reed body 13, the sealing plate 7, the explosion-proof valve 9 and their welded portions 11, and normally functions as an electric circuit.

When an abnormal situation occurs in the battery and gas is generated inside the battery to increase the internal pressure of the battery, the increase in the internal pressure causes the central portion of the explosion-proof valve 9 to move in the internal pressure direction (see FIG. 1).
Then, the welded part 1 is deformed in the upper direction).
After shearing force acts on the thin-walled portion 7a integrated in 1 to break the thin-walled portion 7a, or after the welded portion 11 between the protruding portion 9a of the explosion-proof valve 9 and the thin-walled portion 7a of the sealing plate 7 is peeled off. ,
The thin portion 9b provided in the explosion-proof valve 9 is designed to open so that gas can be discharged from the gas discharge port 8a of the terminal plate 8 to the outside of the battery to prevent the battery from bursting.

Example 2 In the spirally wound electrode body, the uncoated portion on the outer peripheral surface side of the outermost peripheral portion of the positive electrode (that is, the exposed portion of the positive electrode current collector on which the positive electrode active material-containing coating film was not formed) was 70 mm. A length of 10 mm wide and 80 μm thick polyphenylene sulfide tape was adhered to the outer peripheral surface side of the outermost peripheral portion as a positive electrode insulating tape. An electrode body having a wound structure was produced in the same manner as in Example 1 except that the length of the negative electrode active material-containing coating film forming portion on the outer peripheral surface side of the negative electrode was shortened by 20 mm, and A non-aqueous secondary battery was produced.

FIG. 3 schematically shows the outermost peripheral portion of the electrode body of the wound structure of the battery of the second embodiment and the essential portions in the vicinity thereof.

As shown in FIG. 3, in the electrode having the winding structure of the battery of Example 2, the electrode facing the negative electrode can 5 of the electrode having the winding structure is substantially composed of the negative electrode 2. Cage,
The positive electrode 1 has a positive electrode active material-containing coating film 1b formed only on the inner peripheral surface side, and is a plain portion on the outer peripheral surface side of the outermost peripheral portion of the positive electrode 1, that is, the exposed portion of the positive electrode current collector 1a (containing the positive electrode active material). A polyphenine sulfide tape having a width of 10 mm and a thickness of 80 μm is bonded as the positive electrode insulating tape 16 to the outer peripheral surface side of the portion (where the coating film is not formed).
6 is opposed to the lead body 15 welded to the negative electrode current collector 2 a via the separator 3. In addition, the distance between the lead body 15 and the overlapping start portion 17 of the positive electrode active material-containing coating film 1b and the negative electrode active material-containing coating film 2b in the outermost peripheral portion is ¼ of that in the outermost peripheral portion of the negative electrode 2. It is arranged so that it is separated from the circumference. However, in FIG. 3, the two are shown close to each other in order to prevent the figure from becoming too large.

Therefore, in the battery of Example 2, an internal short circuit due to the lead body 15 welded to the negative electrode current collector 2a does not occur under normal use conditions. In addition, the lead body 15
Has a thickness of 0.1 mm (100 μm), the positive electrode insulating tape 16 has a thickness of 80 μm, and the separator 3 has a thickness of 25 μm.
Therefore, the thickness of the lead body 15 is thinner than the total thickness of the positive electrode insulating tape 16 and the thickness of the separator 3, so that even if this battery is forcibly crushed by a crushing test, an internal short circuit will occur. Does not occur. Further, even when the lead body 15 is heated to a high temperature by the external short-circuit test, the separator 3 around the lead body 15 is softened and melted, and the lead body 15 breaks through the separator 3, the positive electrode insulating tape 16 on the inner peripheral side is Since they only come into contact with each other, no internal short circuit occurs, and moreover, the positive electrode active material-containing coating film 1 in the outermost peripheral portion 1
Since the distance between the lead body 15 and the overlapping start portion 17 of the negative electrode active material-containing coating film 2b and the lead body 15 is 1/4 round with respect to one round of the outermost peripheral portion of the negative electrode 2, a secondary internal short circuit occurs. Can be prevented. Further, since the electrode facing the negative electrode can 5 of the wound electrode body is composed of only the negative electrode 2, the separator 3 interposed between the wound electrode body and the negative electrode can 5 is melted and destroyed. Even in the case, the negative electrode can 5 also serving as the negative electrode terminal does not come into contact with the positive electrode 1, and a minute short circuit due to a foreign substance mixed between the electrode body having the winding structure and the negative electrode can 5 hardly occurs. The probability of progressing to an internal short circuit can be reduced, and in the external short circuit test, since the positive electrode 1 does not exist in the electrode facing the negative electrode can 5,
It is possible to prevent a conductive state and to avoid local heat generation.

The discharge capacity per unit volume of the wound electrode body under the standard use conditions of this battery was measured in the same manner as in Example 1. As a result, the discharge capacity per unit volume of the wound electrode body was 138 mAh. / Cm ³ , which was a high capacity. Further, this battery was discharged to 2.75 V at 1700 mA, disassembled, and the winding outer diameter of the electrode body having the winding structure was measured in the same manner as in Example 1. The minimum value was 16.9 m.
m, and the difference between the minimum value portion and the inner diameter of the negative electrode can is 0.
It was 5 mm.

Example 3 A negative electrode lead body was provided on the outer peripheral surface side of the outermost peripheral portion of the negative electrode, and the exposed portion of the negative electrode current collector at the outermost peripheral portion of the negative electrode had a length of 10 mm.
Shorten the length of the forming portion of the negative electrode active material-containing coating film on the outer peripheral surface side of the negative electrode current collector on the second circumference from the outermost peripheral portion of the negative electrode to 20 mm.
A non-aqueous secondary battery was produced in the same manner as in Example 1 except that the length was shortened.

That is, in the wound electrode body of the battery of the third embodiment, as shown in FIG. 4, the electrode facing the negative electrode can 5 of the wound electrode body is substantially composed of the negative electrode 2. Therefore, the outermost peripheral portion of the negative electrode 2 has an exposed portion of the negative electrode current collector 2a on which the negative electrode active material-containing coating film is not formed, and the outermost peripheral portion of the positive electrode 1 has the outer periphery of the positive electrode current collector 1a. The positive electrode active material-containing coating film is not formed on the surface side and the positive electrode current collector 1a is exposed, and the positive electrode active material-containing coating film 1b is formed only on the inner peripheral surface side. The exposed portion of the positive electrode current collector 1a faces the exposed portion of the negative electrode current collector 2a of the negative electrode 2 through the separator 3, and the lead body 15 welded to the negative electrode current collector 2a of the negative electrode 2 is the separator 3 It is arranged so as to face the inner surface of the negative electrode can 5 via the and not directly face the positive electrode 1.
It should be noted that the distance between the lead body 15 and the overlapping start portion 17 of the positive electrode active material-containing coating film 1b and the negative electrode active material-containing coating film 2b in the outermost peripheral portion is the same as that of the positive electrode current collector and the negative electrode current collector in the outermost peripheral portion. By shortening the length by 10 mm, the negative electrode 2 was arranged so as to be separated from the outermost peripheral portion of the negative electrode 1 by 1/5. However, in FIG. 4 as well, in order to prevent the drawing from becoming too large, the two are shown close to each other.

Therefore, the battery of Example 3 has the lead body 15 welded to the negative electrode current collector 2a under normal use conditions.
Does not cause internal short circuit. Further, since the lead body 15 of the negative electrode 2 faces the negative electrode can 5 having a function as a negative electrode terminal, an internal short circuit does not occur even if this battery is forcibly crushed by a crushing test. Further, even if the lead body 15 becomes hot due to the external short-circuit test, the separator 3 around the lead body 15 is softened and melted, and the lead body 15 breaks through the separator 3, it only contacts the negative electrode can 5. The distance between the lead body 15 and the overlapping start portion 17 of the positive electrode active material-containing coating film 1b and the negative electrode active material-containing coating film 2b at the outermost peripheral portion does not cause an internal short circuit, and the distance between the lead body 15 is the outermost peripheral portion. Since it is 1/5 round apart from one round, the occurrence of a secondary internal short circuit can be prevented. Further, the negative electrode 5 that also serves as the negative electrode terminal is used because the negative electrode 2 is the electrode facing the negative electrode can 5 of the wound electrode body.
And the positive electrode 1 face each other via the negative electrode 2, and even if the separator 3 around the lead body 15 of the negative electrode 2 facing the negative electrode can 5 is melted and broken by a crushing test or an external short-circuit test, the positive electrode 1 and the negative electrode There is no contact with the can 5,
A minute short circuit due to foreign matter mixed between the wound electrode body and the negative electrode can 5 is unlikely to occur, and it is possible to reduce the probability of progressing to an internal short circuit during the crushing test. Since the positive electrode 1 does not exist in the electrodes facing each other, it is possible to prevent a conductive state and prevent local heat generation.

The discharge capacity per unit volume of the wound electrode body under the standard use conditions of the battery of this Example 3 was measured in the same manner as in Example 1. As a result, per unit volume of the wound electrode body was measured. Had a high discharge capacity of 138 mAh / cm ³ . Moreover, this battery is 170 up to 2.75V.
After discharging at 0 mA, it was disassembled and the winding outer diameter of the electrode body having the winding structure was measured in the same manner as in Example 1. The minimum value was 16.8 mm, and the minimum value portion and the negative electrode can 5 The difference from the inner diameter of was 0.6 mm.

Example 4 A plain portion (that is, an exposed portion of the positive electrode current collector 1a on which the positive electrode active material-containing coating film is not formed) on the outer peripheral surface side of the outermost peripheral portion of the positive electrode in the wound electrode body is 53 mm. The length of
At the outermost peripheral portion of the negative electrode 1, the negative electrode active material-containing coating film was not formed on both surfaces, and the portion composed only of the negative electrode current collector 2a had a length of 80 mm, and the thickness of the negative electrode lead body was 0.8 mm (80 μm).
An electrode body having a wound structure was produced and a non-aqueous secondary battery was produced in the same manner as in Example 1 except that the above procedure was adopted.

FIG. 5 schematically shows the outermost peripheral portion of the electrode body having the winding structure of the fourth embodiment and the essential portions in the vicinity thereof.

As shown in FIG. 5, in the spirally wound electrode body of the battery according to the fourth embodiment, the electrode facing the negative electrode can 5 of the spirally wound electrode body is substantially composed of the negative electrode 2. Cage,
The negative electrode current collector 2a is formed only in the outermost circumference of the negative electrode 1 or more, and the negative electrode active material-containing coating film is not formed on any of the surfaces thereof. The negative electrode active material-containing coating film 2b is formed on both surfaces of the body 2a, and the lead body 15 welded to the negative electrode current collector 2a of the negative electrode 2 is the second negative electrode of the negative electrode 2 from the outermost peripheral portion via the separator 3. It faces the current collector 2 a and does not directly face the positive electrode 1. Although the positive electrode 1 is also shown at the outermost peripheral portion and the second circumference from the outermost peripheral portion, the positive electrode active material-containing coating film is not formed on the outer peripheral surface side at the outermost peripheral portion, and the positive electrode current collector 1a is The exposed portion is provided for one round or more, and the exposed portion of the positive electrode current collector 1a faces the exposed portion of the negative electrode current collector 2a of the negative electrode 2 through the separator 3 for one round or more. In addition, the distance between the lead body 15 and the overlapping start portion 17 of the positive electrode active material-containing coating film 1b and the negative electrode active material-containing coating film 2b in the outermost periphery is 1/3 of the circumference of the outermost periphery of the negative electrode. I placed them apart. However, in FIG. 5, the two are shown close to each other in order to prevent the drawing from becoming too large.

Therefore, the battery of Example 4 has a lead body 15 welded to the negative electrode current collector 2a under normal use conditions.
Does not cause internal short circuit. In particular, in the battery having the above-mentioned wound electrode body, the lead body 15 provided on the outermost peripheral portion of the negative electrode 2 faces the negative electrode 2 on the second circumference from the outermost peripheral portion, and The thickness of the lead body 15 is 0.8 mm (80 μm), and the negative electrode current collector 2
The thickness of a is 10 μm, and the thickness of the separator 3 is 25 μm.
The thickness of the lead body 15 welded to the negative electrode current collector 2a is 5 from the total thickness of the thickness of the negative electrode 2 and the thickness of the separator 3 (thickness of the negative electrode 2 + thickness of the separator 3 × 3).
Therefore, in the battery of Example 4, the lead body 15 welded to the negative electrode current collector 2a presses the negative electrode 2 in the second lap from the outermost peripheral portion even if the crush test forcibly crushes the battery.
The negative electrode current collector 2a on the inner peripheral side does not break through the separator 3 and come into contact with the positive electrode 1 to cause an internal short circuit. Further, in both the positive electrode 1 and the negative electrode 2, there is no portion where one or more outermost circumferences are opposed to each other by the active material-containing coating film having a high resistance, and the negative electrode current collector 2b and the positive electrode current collector 1 having a low resistance at any position
Since a short circuit will occur with b, heat generation due to an internal short circuit can be further reduced. Since the electrode facing the negative electrode can 5 of the wound electrode body is composed only of the negative electrode 2, the negative electrode can 5 also serving as the negative electrode terminal and the positive electrode 1 face each other through the negative electrode 2, and thus the crushing is performed. Even if the separator 3 interposed between the wound electrode body and the negative electrode can 5 is melted or broken by a test or an external short circuit test, an internal short circuit or a secondary short circuit due to contact between the positive electrode 1 and the negative electrode can 5 may occur. It does not occur, and a minute short circuit due to foreign matter mixed between the wound electrode body and the negative electrode can 5 is unlikely to occur, and the probability of progressing to an internal short circuit during a crushing test can be reduced.
Moreover, in the external short-circuit test, since the positive electrode 1 is not present on the electrode facing the negative electrode can 5, it is possible to prevent the conductive state and prevent local heat generation.

The discharge capacity per unit volume of the wound electrode body under the standard use conditions of this battery was measured in the same manner as in Example 1. The discharge capacity per unit volume of the wound electrode body was 138 mAh. / Cm ³ , which was a high capacity. Further, this battery was discharged to 2.75 V at 1700 mA, disassembled, and the winding outer diameter of the electrode body having the winding structure was measured in the same manner as in Example 1. The minimum value was 16.7 m.
m, and the difference between the minimum value portion and the inner diameter of the negative electrode can was 0.7 mm.

Comparative Example 1 In the electrode body having the wound structure of Example 1, the outermost peripheral portion of the positive electrode was a blank portion on the outer peripheral surface side of the positive electrode current collector (that is, the positive electrode active material-free coating film was not formed). The exposed part of the current collector) is cut from the start end to the end, and the inner part is left from the part where the positive electrode active material-containing coating film is formed on both surfaces of the positive electrode current collector, while the negative electrode side has a winding structure. The uncoated portion of the negative electrode current collector on the outermost peripheral side of the negative electrode in the electrode body (that is, the exposed portion of the negative electrode current collector on which the negative electrode active material-containing coating film is not formed) is 5 mm for attaching the lead body. Leave it, cut the part from there, and leave the remaining negative electrode current collector exposed part 5 mm
We used a lead body with a width of 4 mm and a thickness of 0.3 mm (cross-sectional area 1.2 mm ² ) that was welded and attached to the inner peripheral surface side of the long part. An electrode body having a wound structure was prepared and a non-aqueous secondary battery was prepared in the same manner as in Example 1 except that the positional relationship of the outermost peripheral part was schematically shown in FIG. 7. The positive electrode active material-containing coating film 1b and the negative electrode active material-containing coating film 2b in the outermost peripheral portion
The distance between the overlapping start portion 17 and the lead body 15 was set to be 1/12 round with respect to one round of the outermost peripheral portion of the negative electrode 2. However, in FIG. 7 as well, in order to prevent the drawing from becoming too large, the two are shown in close proximity.

As shown in FIG. 7, in the electrode body having the winding structure of the battery of Comparative Example 1, the positive electrode current collector 1a of the positive electrode 1 was used.
The positive electrode active material-containing coating film 1b is formed on both surfaces of the negative electrode current collector 2a and the lead body 15 welded to the inner peripheral surface side of the tip of the negative electrode current collector 2a faces the positive electrode active material-containing coating film 1b of the positive electrode 1 through the separator 3. is doing.

Therefore, in the battery of Comparative Example 1,
Under normal use conditions, the separator 3 prevents contact between the positive electrode 1 and the lead body 15 welded to the negative electrode current collector 2a.
The lead body 15 of the negative electrode 2 breaks through the separator 3 to bring the lead body 15 of the negative electrode 2 into contact with the positive electrode 1 to cause an internal short circuit.

The discharge capacity per unit volume of the wound electrode body under the standard use condition of the battery of Comparative Example 1 was measured in the same manner as in Example 1. As a result, per unit volume of the wound electrode body was measured. Had a discharge capacity of 134 mAh / cm ³ .
Further, this battery was discharged to 2.75 V at 1700 mA, disassembled, and the winding outer diameter of the electrode body having the winding structure was measured in the same manner as in Example 1. The minimum value was 16.4 mm. The difference between the minimum value part and the inner diameter of the negative electrode can 5 is 1.0.
It was mm.

Comparative Example 2 The portions where the positive electrode current collector of the positive electrode and the positive electrode active material-containing coating film of Comparative Example 1 were formed were each 47 mm longer, and the negative electrode current collector of the negative electrode and the negative electrode active material-containing coating film were formed. 47mm longer for each, and the separator is 47mm accordingly.
An electrode body having the same winding structure as that of Comparative Example 1 was produced except that the length was increased, and a non-aqueous secondary battery was produced.

The discharge capacity per unit volume of the wound electrode body under the standard use conditions of the battery of Comparative Example 2 was measured in the same manner as in Example 1. The discharge per unit volume of the wound electrode body was measured. The capacity was 150 mAh / cm ³ . In addition, the battery of Comparative Example 2 was set to 1.75 mA up to 2.75 V.
After discharging, the battery was disassembled and the winding outer diameter of the electrode body having the winding structure was measured in the same manner as in Example 1. The minimum value was 17.
It was 1 mm, and the difference between the minimum value portion and the inner diameter of the negative electrode can 5 was 0.3 mm.

Comparative Example 3 In the spirally wound electrode body of Comparative Example 1, the outermost peripheral portion of the positive electrode was extended by 30 mm, and as shown in FIG. An electrode body having a wound structure was produced in the same manner as in Comparative Example 1 except that both the positive electrode and the negative electrode were present in the outer peripheral portion, and a non-aqueous secondary battery was produced.

As shown in FIG. 8, in the electrode body having the winding structure of the battery of Comparative Example 3, the positive electrode current collector 1a of the positive electrode 1 was used.
The positive electrode active material-containing coating film 1b is formed on both surfaces of the negative electrode current collector 2a, and the lead body 15 welded to the inner peripheral surface side of the tip of the negative electrode current collector 2a faces the positive electrode current collector 1a of the positive electrode 1 through the separator 3. There is.

Therefore, in the battery of Comparative Example 3,
Under normal use conditions, the lead body 15 welded to the negative electrode current collector 2a by the separator 3 and the positive electrode current collector 1a of the positive electrode 1
Although it is prevented from coming into contact with the separator 3, if it is subjected to a crushing test and forcibly crushed, for example, the lead body 15 of the negative electrode 2 will be separated from the separator 3.
By breaking through, the lead body 15 of the negative electrode 2 and the positive electrode current collector 1a come into contact with each other, and an internal short circuit occurs.

The discharge capacity per unit volume of the wound electrode body under the standard use condition of the battery of Comparative Example 3 was measured in the same manner as in Example 1. As a result, per unit volume of the wound electrode body was measured. Had a discharge capacity of 134 mAh / cm ³ .
Further, this battery was discharged to 2.75 V at 1700 mA, disassembled, and the winding outer diameter of the electrode body having the winding structure was measured in the same manner as in Example 1. The minimum value was 16.5 mm. The difference between the minimum value part and the inner diameter of the negative electrode can 5 is 0.9.
It was mm.

After discharging the batteries of Examples 1 to 4 and Comparative Examples 1 to 3 to 2.75 V at 1700 mA, 170
After charging with 0mA and reaching 4.25V, 4.25V
The battery was charged for two and a half hours under the condition that the constant voltage was maintained. Then, the battery was subjected to a crush test or a nail penetration test.

In the crush test, a battery charged to 4.25 V was crushed as it was with a force of 1 ton to examine whether an internal short circuit occurred. In the nail penetration test, a battery charged to 4.25 V was put in a constant temperature bath at 45 ° C. and taken out 2 hours later, the battery was placed on a holder, and a 1/2 nail penetration test was performed. That is, a stainless steel nail having a diameter of 3 mm was pierced from the side surface of the battery to a position half the diameter of the battery, and the number of batteries which abnormally generated heat among 20 batteries was checked. Further, in the external short-circuit test, after the PTC element was prevented from operating in advance, the battery charged to 4.25V was put in a constant temperature tank at 45 ° C and stored for 2 hours, and forcibly short-circuited externally in the constant temperature tank. Then, the number of the 20 batteries that abnormally generated heat was checked. The results are shown in Table 1. In Table 1, the denominator of the numerical value showing the result is the number of batteries used in the test, the numerator is the number of batteries in which an internal short circuit occurred in the crush test, and the number of batteries that abnormally generated heat in the nail penetration test and the external short circuit test. Note that abnormal heat generation means that the battery surface temperature is 15
When the temperature is 0 ° C or higher.

[0114]

[Table 1]

As shown in Table 1, the batteries of Examples 1 to 4 were less likely to cause a short circuit in the crush test than the batteries of Comparative Examples 1 to 3 and were pierced with nails even under a severe condition of 45 ° C. There was little abnormal heat generation in the test and the external short circuit test. Also,
In the batteries of Examples 1 to 4, in the outermost peripheral portion of the positive electrode, a portion where the positive electrode active material-containing coating film of the positive electrode current collector was not formed was present once on the outer peripheral surface side, and the cross-sectional area of the negative electrode lead body Was 0.1 to 1.0 mm ² , safety could be improved even in the 1/2 nail penetration test, crush test, and external short-circuit test, and high safety could be secured. Furthermore, in the batteries of Examples 1 to 4, the total thickness (thickness of the negative electrode + thickness of the separator × 3) of the thickness of the negative electrode and the thickness of the separator at the portion where the thicknesses of the lead bodies of the negative electrode are opposed to each other or the positive electrode insulation Since it is thinner than the total thickness of the thickness of the tape and the thickness of the separator (thickness of the positive electrode insulating tape + thickness of the separator), it can be seen that high safety is obtained even in the crush test. Further, in the batteries of Examples 1 to 3, since the outermost peripheral portion of the electrode body is only the current collector, the heat dissipation effect at the time of short circuit is excellent, and the occurrence rate of abnormal heat generation is suppressed.

On the other hand, in the batteries of Comparative Examples 1 to 3,
Since the lead body welded to the negative electrode current collector faced the positive electrode via the separator, an internal short circuit was likely to occur in the crushing test, and abnormal heat generation occurred in the nail penetration test at 45 ° C. In particular, the battery of Comparative Example 2 has a long coating film forming portion, and the difference between the outer diameter of the wound electrode body and the inner diameter of the negative electrode can is 0.
Since it is only 3mm, the battery charging voltage is set to 4.25V,
Even when the nail penetration test was performed at room temperature, there were some that generated abnormal heat. In Comparative Example 3, the positive electrode active material-containing coating film faces the negative electrode active material-containing coating film at the outermost peripheral portion of the positive electrode, the lead body of the negative electrode directly faces the positive electrode current collector, and Since one round does not have a single electrode, the safety was poor in any test.

[0117]

As described above, according to the present invention, it is possible to provide a non-aqueous secondary battery having high capacity and high safety.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view schematically showing the structure of a battery of Example 1 of a non-aqueous secondary battery of the present invention.

FIG. 2 is a lateral cross-sectional view showing, in an enlarged manner, an outermost peripheral portion of an electrode body having a wound structure of a battery of Example 1 and a main portion in the vicinity thereof.

FIG. 3 is a lateral cross-sectional view showing, in an enlarged manner, an outermost peripheral portion of an electrode body of a battery winding structure of Example 2 and a main portion in the vicinity thereof.

FIG. 4 is a lateral cross-sectional view showing, in an enlarged manner, an outermost peripheral portion of an electrode body having a wound structure of a battery of Example 3 and a main portion in the vicinity thereof.

FIG. 5 is a lateral cross-sectional view showing, in an enlarged manner, an outermost peripheral portion of an electrode body having a wound structure of a battery of Example 4 and a main portion in the vicinity thereof.

FIG. 6 is a cross-sectional view showing, in an enlarged manner, the outermost peripheral portion of the electrode body of the non-aqueous secondary battery of the present invention having a winding structure other than that of the above-described embodiment and the essential portions in the vicinity thereof.

FIG. 7 is a lateral cross-sectional view showing, in an enlarged manner, an outermost peripheral portion of an electrode body having a wound structure of a battery of Comparative Example 1 and a main portion in the vicinity thereof.

FIG. 8 is an enlarged transverse cross-sectional view showing an outermost peripheral portion of an electrode body having a wound structure of a battery of Comparative Example 3 and a main portion in the vicinity thereof.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Positive electrode 1a Positive electrode collector 1b Positive electrode active material-containing coating film 2 Negative electrode 2a Negative electrode current collector 2b Negative electrode active material-containing coating film 3 Separator 5 Negative electrode can 15 Lead body 16 Positive electrode insulating tape 17 Outermost periphery of wound electrode body Part where the positive electrode active material-containing coating film overlaps the negative electrode active material-containing coating film

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuki Ishikawa 1-88, Tora Tora, Ibaraki City, Osaka Prefecture Hitachi Maxell Co., Ltd. (72) Inventor Koji Murakami 1-88 Tora Torra, Ibaraki City, Osaka Hitachi Maxell Incorporated (72) Inventor Fusatsu Kita 1-88, Torora, Ibaraki, Osaka Prefecture Hitachi Maxell Co., Ltd. (56) Reference JP 10-241737 (JP, A) JP 7-320770 ( JP, A) JP 2-51875 (JP, A) JP 9-330725 (JP, A) JP 10-162859 (JP, A) JP 8-153542 (JP, A) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) H01M 10/36-10/40 H01M 10/04 H01M 2/26 H01M 4/02

Claims (5)

(57) [Claims] 1. A positive electrode having a positive electrode active material-containing coating film formed on both sides of at least a part of a positive electrode current collector, and a negative electrode active material-containing coating film on both sides of at least a part of a negative electrode current collector. A non-aqueous secondary battery in which an electrode body having a wound structure is housed in a negative electrode can, wherein the formed negative electrode is wound with a separator interposed between the negative electrode can and the negative electrode can of the wound structure electrode body. The electrode is substantially composed of a negative electrode, and the positive electrode active material-containing coating film is not formed on the outer peripheral surface side of the positive electrode current collector of at least the outermost peripheral portion of the positive electrode in the electrode body having the winding structure. Practical
At least one turn , the portion of the positive electrode current collector where the positive electrode active material-containing coating film is not formed faces the negative electrode through the separator, and the lead body welded to the negative electrode current collector passes through the positive electrode through the separator. Facing the positive insulating tape that is bonded to the current collector
Nonaqueous secondary battery, characterized in that there. 2. A positive electrode in which a positive electrode active material-containing coating film is formed on both sides of at least a part of the positive electrode current collector, and a negative electrode active material-containing coating film on both sides of at least a part of the negative electrode current collector. A non-aqueous secondary battery in which an electrode body having a wound structure is housed in a negative electrode can, wherein the formed negative electrode is wound with a separator interposed between the negative electrode can and the negative electrode can of the wound structure electrode body. The electrode is substantially composed of a negative electrode, and the positive electrode active material-containing coating film is not formed on the outer peripheral surface side of the positive electrode current collector of at least the outermost peripheral portion of the positive electrode in the electrode body having the winding structure. Practical
A part of the positive electrode current collector on which the positive electrode active material-containing coating is not formed faces the negative electrode via the separator, and the lead body welded to the negative electrode current collector has the negative electrode via the separator. nonaqueous secondary battery, characterized in that you are the inner surface facing the can. 3. The positive electrode current collector has at least a part thereof on both sides.
A positive electrode formed by forming a coating film containing a positive electrode active material, and a negative electrode current collector
Coating film containing negative electrode active material is formed on both sides of at least a part of
The wound structure in which the negative electrode formed by
It is a non-aqueous secondary battery in which the manufactured electrode body is housed in a negative electrode can.
Then, the electrode facing the negative electrode can of the wound electrode body is actually
It is qualitatively composed of a negative electrode,
At least the outermost peripheral surface of the positive electrode in the positive electrode current collector outer peripheral surface
Substantially the part where the positive electrode active material-containing coating film is not formed on the side
A coating film containing the positive electrode active material of the positive electrode current collector, which is provided for one or more turns
The part not formed faces the negative electrode through the separator
And, and lead body in contact soluble in the anode current collector separator
Welded to the negative electrode current collector without directly facing the positive electrode via
The thickness of the negative electrode and the separator where the lead bodies face each other
Total thickness (thickness of negative electrode + separator)
Non-aqueous secondary battery characterized by being thinner than the thickness x 3) of
pond. 4. At least a part of the positive electrode current collector is provided on both sides.
A positive electrode formed by forming a coating film containing a positive electrode active material, and a negative electrode current collector
Coating film containing negative electrode active material is formed on both sides of at least a part of
The wound structure in which the negative electrode formed by
It is a non-aqueous secondary battery in which the manufactured electrode body is housed in a negative electrode can.
Then, the electrode facing the negative electrode can of the wound electrode body is actually
It is qualitatively composed of a negative electrode,
At least the outermost peripheral surface of the positive electrode in the positive electrode current collector outer peripheral surface
Substantially the part where the positive electrode active material-containing coating film is not formed on the side
A coating film containing the positive electrode active material of the positive electrode current collector, which is provided for one or more turns
The part not formed faces the negative electrode through the separator
And the lead body welded to the negative electrode current collector
Welded to the negative electrode current collector without directly facing the positive electrode via
The lead body and the positive electrode at the outermost periphery of the wound electrode body
Overlapping start part between coating film containing active material and coating film containing negative electrode active material
Distance to minutes (distance between the closest parts of both)
Is 1 for one round of the negative electrode at the outermost peripheral part of the wound electrode body.
/ 6 or more and 1/2 or less laps apart
Water secondary battery. 5. The electrode of the spirally wound electrode body facing the negative electrode can is composed of a negative electrode, and the outermost peripheral portion of the negative electrode has a portion where neither active material-containing coating film is formed on both surfaces of the negative electrode current collector. The non-aqueous secondary battery according to any one of claims 1 to 4 , wherein the non-aqueous secondary battery substantially exists for one or more turns.