JP5294641B2 - Sealed battery - Google Patents

Description

  The present invention relates to a sealed battery, and in particular, by reviewing the structure of a current collecting tab of one electrode plate, it has excellent shock resistance or vibration resistance, and is used for an electric vehicle (EV), a hybrid electric vehicle (HEV), and an electric motor. The present invention relates to a sealed battery such as a non-aqueous electrolyte secondary battery that is optimal for tools.

  Emission regulations such as carbon dioxide gas have been strengthened against the background of the recent increase in environmental protection movement. Therefore, not only automobiles that use fossil fuels such as gasoline, diesel oil, and natural gas but also EVs and HEVs are being actively developed in the automobile industry. As batteries used for these EV and HEV applications, non-aqueous electrolyte secondary batteries represented by lithium ion secondary batteries and sealed batteries such as nickel metal hydride batteries are increasingly used. Such a tendency is the same also in the use of a power tool.

  As these EV and HEV batteries or tool batteries, a large amount of electric power is taken out in a short period of time necessary for sufficiently exhibiting basic performance for automobiles or electric tools, that is, acceleration performance, startability, etc. Capability, that is, higher output is also required. However, when a high output discharge is performed, a large current flows through the battery, so that heat generation inside the battery increases. Therefore, as the battery for EV, HEV or tool, not only is it large and has a large capacity, but also it is necessary to take out a large current in a short time. Various improvements have been made to reduce heat generation.

  In many conventional sealed batteries, a configuration for preventing power loss in the battery and reducing heat generation has a problem of increasing the current collection efficiency from the core of the electrode plate. In this case, it is obvious that the current collection efficiency from the core of the electrode plate can be increased by increasing the width of the current collecting tab and increasing the mounting area of the electrode plate to the core. However, particularly in a sealed battery using a cylindrical wound electrode body, the configuration in which the width of the current collecting tab is simply widened is that the mounting surface of the current collecting tab has a curved surface. Since it becomes difficult to incorporate it into the can, it cannot be adopted as it is. Therefore, in the invention of the cylindrical secondary battery disclosed in Patent Document 1 below, it is molded to the same radius of curvature as the core rod used when the wound electrode body is produced as a current collecting tab of the innermost electrode. I am using something.

On the other hand, in Patent Document 2 below, as a comparative example, in order to reduce the contact resistance between the negative electrode current collecting tab and the battery outer can, the negative electrode current collecting tabs are arranged on the winding start side and the winding end side of the negative electrode core. Two sealed batteries are disclosed. In the sealed battery disclosed in Patent Document 2 below, the current collecting tab provided on the winding end side after the winding electrode body is produced is bent toward the winding center, and winding is started at the inner bottom portion of the battery outer can. Three layers of the current collecting tab on the side, the current collecting tab on the winding end side, and the battery outer can are welded and electrically connected.
Japanese Patent No. 2764958 JP 2007-220601 A Japanese Utility Model Publication No. 5-23414

  According to the invention disclosed in Patent Document 1 described above, the contact area between the innermost electrode and the current collecting tab can be increased. A separate process for forming the same radius of curvature as the core rod used is required. In addition, Patent Document 1 does not suggest any electrical connection by joining the current collecting tab to the inner bottom portion of the battery outer can.

  In the invention disclosed in Patent Document 2, the current collecting tab is connected to the core on both the winding start side and the winding end side of the wound electrode body. Therefore, even if the current collecting tab width is the same as that of the conventional example, two conductive paths between the winding start side of the core body and the battery outer can and between the winding end side of the core body and the battery outer can are secured. Therefore, a sealed battery with low internal resistance is obtained.

  However, characteristics required for batteries for EVs, HEVs, and electric tools include high mechanical strength and reliability under severe use conditions. That is, batteries for EVs, HEVs or power tools are exposed to drops (especially in the case of power tools), impacts and vibrations during use, so it is necessary to improve the above-mentioned characteristics. is there. Therefore, a vibration test, a drop test, a drum test (in-drum rotation test), and the like are performed before shipping the sealed battery as a product.

  According to the nonaqueous electrolyte secondary battery disclosed in Patent Document 2, when the cylindrical wound electrode body is exposed to a drop, impact or vibration, the wound electrode body vibrates in the battery outer can. . The battery outer can and the current collecting tab drawn out from the wound electrode body maintain electrical conductivity by welding, but in the vibration test, drop test, drum test, etc. Fatigue may occur, the current collecting tab may come off, and the internal resistance may increase, resulting in a state where the product cannot be used.

  In Patent Document 3, as shown in FIG. 6, in order to prevent the current collecting tab from being cut when an impact is applied due to the battery dropping or the like, A battery 50 in which a convex bent portion 54 is formed on a current collecting tab 53 attached to an electrode 52 on the outermost peripheral side, and a tip 54 ′ of the bent portion 54 of the current collecting tab 53 is joined to a battery outer can 55. Is disclosed. FIG. 6 is a longitudinal sectional view of the battery in the middle of assembly disclosed in Patent Document 3. However, Patent Document 3 does not suggest any electrical connection by connecting the current collecting tab 53 to the bottom of the battery outer can 55.

  The present invention has been made to solve the above-mentioned problems of the prior art. That is, the present invention makes it easy to perform the joining between the current collecting tab and the inner bottom portion of the battery outer can by reexamining the structure of the current collecting tab of the wound electrode body, and also has impact resistance or vibration resistance. It is an object of the present invention to provide a sealed battery that is excellent in use for EVs, HEVs, and electric tools.

In order to achieve the above object, the sealed battery of the present invention includes a positive electrode plate in which a positive electrode mixture layer is formed on both surfaces of a positive electrode core, and a negative electrode plate in which a negative electrode mixture layer is formed on both surfaces of the negative electrode core. Is wound around a separator, and has a wound electrode body in which a gap is formed at the center of the winding shaft, and the wound electrode body has one electrode plate located on the innermost circumference side on the outermost circumference side. The core exposed portion is formed on the winding start side of the one electrode plate, and the winding start current collecting tab is formed on the core exposed portion on the winding start side. The winding start portion current collecting tab is bent so as to contact the inner bottom portion of the battery outer can at a position corresponding to the gap portion of the wound electrode body, and joined to the inner bottom portion of the battery outer can. in the sealed battery that is, the winding start portion current collector tabs, elasticity in the gap portion of the wound electrode body Characterized in that it comprises a shaped portion.

According to the sealed battery of the present invention, the winding start portion current collecting tab is formed with a shape portion having elasticity in the gap portion of the wound electrode body . Therefore, even if an impact due to dropping, vibration or the like is applied to the sealed battery of the present invention, this impact is absorbed by the shape part having elasticity of the winding start part current collecting tab, so the winding start part current collecting tab and the battery The possibility of separation of the joint between the outer can and the case greatly decreases, and the internal resistance of the battery hardly increases. In addition, as a shape part which has the elasticity of the winding start part current collection tab in the sealed battery of this invention, shapes, such as an arc shape and a waveform shape, are employable. Further, “joining” in the present invention includes not only “welding” but also “pressure welding”, and “welding” includes resistance welding, ultrasonic welding, laser welding, and electron beam welding.

In addition, as a negative electrode active material in the nonaqueous electrolyte secondary battery of the present invention, a carbonaceous material such as graphite or amorphous carbon can be used. Further, as the positive electrode active material, a lithium transition metal represented by Li _x MO ₂ (wherein M is at least one of Co, Ni, and Mn) capable of reversibly occluding and releasing lithium ions. Complex oxides, that is, LiCoO ₂ , LiNiO ₂ , LiNi _y Co _1-y O ₂ (y = 0.01 to 0.99), LiMnO ₂ , LiMn ₂ O ₄ , LiCo _x Mn _y Ni _z O ₂ (x + y + z) = 1), or LiFePO ₄ can be used singly or in combination.

Moreover, as a solvent (organic solvent) of the non-aqueous electrolyte, carbonates, lactones, ethers, esters and the like can be used alone or in admixture of two or more. Among these, carbonates having a large dielectric constant and a high ionic conductivity of the non-aqueous electrolyte are preferable. In addition, as a solute of the nonaqueous electrolyte, LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C _{4 F 9 SO 2), LiC} (CF 3 SO 2) 3, LiC (C 2 F 5 SO 2) 3, LiAsF 6, LiClO 4, Li 2 B 10 Cl 10, Li 2 B 12 Cl 12 and the like and their Mixtures can be used.

  In addition, aluminum foil is generally used as the positive electrode core of the nonaqueous electrolyte secondary battery of the present invention, and copper foil is used as the negative electrode core, and the battery outer can and terminal are iron-based such as stainless steel. These alloys are generally used. Therefore, in consideration of easiness of joining, joining strength, etc., the positive electrode current collecting tab is preferably made of aluminum, and the negative electrode current collecting tab is nickel or a nickel alloy, a copper-nickel two-layer clad material or A nickel-copper-nickel three-layer clad material is preferred.

  Further, in the sealed battery of the present invention, a winding end current collecting tab is joined to the core exposed portion on the winding end side of the one electrode plate, and the winding end current collecting tab is the above-mentioned winding electrode body. It is preferable that it is bent so as to contact the inner bottom of the battery outer can at a position corresponding to the gap, and is integrally joined together with the winding start current collecting tab and the inner bottom of the battery outer can.

  According to the sealed battery of this aspect, even if the width of the current collecting tab is the same as that of the conventional example, between the core at the winding start portion and the battery outer can and between the core at the winding end and the battery outer can. Since two conductive paths are ensured, a sealed battery having a smaller internal resistance can be obtained.

  In the sealed battery of the present invention, it is preferable that the core exposed portion on the winding start side of the one electrode plate is not less than 1 and not more than 3 times of the outer periphery of the gap.

  According to the sealed battery of this aspect, since the innermost circumferential side is the core exposed part on the winding start side of the one electrode plate, the shape of the gap is small and the core has elasticity. Even if the portion is bent and comes into contact with the surrounding innermost electrode plate, problems such as separation of the mixture layer do not occur. In addition, when the core exposed portion on the winding start side of the one electrode plate is less than one round of the outer periphery of the gap portion, the mixture layer of the innermost electrode plate is exposed to the gap portion side. Therefore, when the shape part which has the elasticity of the 1st current collection tab bends and contacts the surrounding innermost electrode board, problems, such as peeling of a mixture layer, arise, and it is not preferred. Further, if the core exposed portion on the winding start side of the one electrode plate is three or more rounds of the outer periphery of the gap, the volume occupied by the innermost core exposed portion becomes too large, and the battery capacity is increased. This is not preferable because it leads to a decrease in the temperature.

  Further, in the sealed battery of the present invention, the winding start portion current collecting tab includes a portion having the elastic shape up to the joint portion with the battery outer can, and the core on the winding start side of the one electrode plate. It can be said that it is joined to the outer surface of the body exposed portion.

  According to the sealed battery of this aspect, since the current collecting tab is joined to the winding outside of the core exposed portion on the winding start side of the one electrode plate, the portion including the elastic shaped portion is joined. Even if strong vibration is applied from the outside, the current collecting tab of the elastically shaped portion follows the deformation of the core body, so that the current collecting tab may come off from the core body or the internal resistance may increase. Is greatly reduced.

  In the sealed battery of the present invention, it is preferable that the sealed battery is a nonaqueous electrolyte secondary battery, and the one electrode plate is a negative electrode plate.

  In a nonaqueous electrolyte secondary battery typified by a lithium ion secondary battery as a sealed battery, generally, the charge capacity ratio (negative electrode charge capacity / positive electrode charge capacity) at a portion where the positive electrode plate and the negative electrode plate face each other is 1. It is larger than, for example, about 1.1. Accordingly, when one electrode plate located on the innermost peripheral side as in the present invention is a negative electrode plate, the negative electrode plate is easily wound on the outermost peripheral side, so that the negative electrode is easily provided. The charge capacity ratio of the plate can be made larger than the charge capacity ratio of the positive electrode plate.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described in detail below using each example and comparative example. However, the examples shown below illustrate a nonaqueous electrolyte secondary battery as a sealed battery for embodying the technical idea of the present invention, and the present invention is specified as this nonaqueous electrolyte secondary battery. However, the present invention can be equally applied to various modifications without departing from the technical concept shown in the claims.

  1A is a development view of a positive electrode plate used in the nonaqueous electrolyte secondary batteries of Examples and Comparative Examples, and FIG. 1B is a development view of the negative electrode plate. 2 is a longitudinal sectional view of the nonaqueous electrolyte secondary battery of Example 1. FIG. 3 is a longitudinal sectional view of the nonaqueous electrolyte secondary battery of Example 2. FIG. 4 is a longitudinal sectional view of the nonaqueous electrolyte secondary battery of Comparative Example 1. FIG. 5 is a longitudinal sectional view of a nonaqueous electrolyte secondary battery of Comparative Example 2. FIG.

  First, the configuration of the positive electrode plate, the negative electrode plate, and the non-aqueous electrolyte common to Examples 1 and 2 and Comparative Examples 1 and 2 will be described with reference to FIG.

[Preparation of positive electrode plate]
The positive electrode plate 11 was produced as follows. First, 90 parts by mass of a positive electrode active material in which nickel cobalt lithium manganate (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ) and a spinel type lithium manganate as a positive electrode active material were mixed at a mass ratio of 1: 1. Then, 5 parts by mass of graphite as a conductive agent and 5 parts by mass of polyvinylidene fluoride (PVdF) as a binder were dispersed in N-methyl-2-pyrrolidone to prepare a positive electrode mixture slurry. Next, the positive electrode mixture slurry is applied so that the central portion 11b and the winding end side end portion 11c of the positive electrode core body 11a are exposed on both surfaces of the positive electrode core body 11a made of an aluminum foil having a thickness of 20 μm. The organic solvent was removed by passing through a drier, and then rolled using a roll press so that the thickness of the portion where the positive electrode mixture layer 11d was formed was 100 μm. Next, a positive electrode current collecting tab 11e made of, for example, aluminum was attached to the exposed surface of the central portion 11b of the positive electrode core body 11a by ultrasonic welding to obtain the positive electrode plate 11 (see FIG. 1A).

[Production of negative electrode plate]
The negative electrode plate 12 was produced as follows. First, 98% by mass of artificial graphite powder as a negative electrode active material and 1% by mass of carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) as a binder are mixed, and water is added and kneaded to form a negative electrode. A mixture slurry was prepared. Next, the negative electrode mixture is formed so that both sides of the winding start side end 12b and the winding end side end 12c of the negative electrode core 12a are exposed on both sides of the negative electrode core 12a made of copper foil having a thickness of 15 μm. The slurry was applied, then passed through a dryer and dried, and then rolled using a roll press so that the thickness of the negative electrode mixture layer 12d was 100 μm. Next, negative electrode current collecting tabs 12e ₁ and 12e ₂ made of, for example, a copper-nickel clad material (thickness: 150 μm) are exposed on the exposed surfaces of the winding start side end 12b and the winding end side end 12c of the negative electrode core 12a. Were ultrasonically welded so that they face each other. The amount of the negative electrode mixture applied is the charge capacity ratio (negative electrode charge capacity / positive electrode charge capacity) at the portion where the positive electrode plate 11 and the negative electrode plate 12 face each other at the charge voltage (4.2 V) which is the design standard. Was adjusted to 1.1.

[Production of wound electrode body]
The positive electrode plate 11, the negative electrode plate 12, and the microporous separator 13 made of polyethylene resin and having a thickness of 22 μm are wound by a winder, and an insulating winding stop is formed at the winding end portion. The tape was attached, and the cylindrical wound electrode body 14 used in the nonaqueous electrolyte secondary batteries 10A to 10D of Examples 1 and 2 and Comparative Examples 1 and 2 was completed. The length of the exposed portion of the innermost negative electrode core 12 b was set to be two rounds of the outer periphery of the gap portion 18.

[Preparation of non-aqueous electrolyte]
A non-aqueous mixed solvent was prepared so as to be 15% by volume of ethylene carbonate (EC), 10% by volume of propylene carbonate (PC) and 75% by volume of dimethyl carbonate (DMC), and a ratio of 1.0 mol / L of LiPF ₆ was added thereto. What was melt | dissolved so that it might become was set as the non-aqueous electrolyte.

[Production of Battery of Example 1]
Insulating plates 15 and 16 having a hole in the center are arranged above and below the wound electrode body 14 produced as described above, and the negative electrode current collecting tab 12e ₁ on the winding end side of the negative electrode plate 12 is placed at the tip. Was bent at an appropriate position so as to be parallel to the bottom of the battery outer can 17. Further, the negative electrode current collecting tab 12e ₂ on the winding start side of the negative electrode plate 12 is attached to the winding inner side surface of the exposed portion 12b of the negative electrode core 12, and has a shape having elasticity on the gap portion 18 side, for example, an arc with bent so shaped portion 12f is formed, by bending the tip portion so as to overlap the front end portion of the bottom of the way and the winding end-side parallel to the section collector tab 12e ₁ of the battery outer can 17. The wound electrode body 14 provided with the negative electrode current collecting tabs 12e ₁ and 12e ₂ bent in this way was inserted into a cylindrical battery outer can 17 as shown in FIG. Next, the negative electrode current collecting tabs 12e ₁ and 12e ₂ were fixed to the inside of the bottom of the battery outer can 17 by resistance welding.

  Further, the tip of the positive electrode current collecting tab 11d is ultrasonically welded to the positive electrode terminal 20 attached to the insulating sealing plate 19, and the above-mentioned non-aqueous electrolyte is injected into the battery outer can and vacuum impregnated. The nonaqueous electrolyte secondary battery 10A of Example 1 was manufactured by sandwiching the periphery of the sealing plate 19 with the gasket 21 and fixing the opening end of the battery outer can 17 by caulking. The nonaqueous electrolyte secondary battery 10A of Example 1 had a diameter of 18 mm, a length of 65 mm, and a design capacity of 1200 mAh.

[Production of Battery of Example 2]
In the non-aqueous electrolyte secondary battery 10B of Example 2, the negative electrode current collecting tab 12e ₂ on the winding start side used in Example 1 was exposed to the innermost peripheral negative electrode core 12 as shown in FIG. It was ultrasonically welded to the winding outer surface of the part 12b, and the other configuration was produced in the same manner as in the case of the nonaqueous electrolyte secondary battery 10A of Example 1.

[Production of Battery of Comparative Example 1]
As shown in FIG. 4, the nonaqueous electrolyte secondary battery 10 </ _b > C of Comparative Example 1 is perpendicular to the bottom of the battery outer can 17 in the negative electrode current collecting tab 12 e ₂ on the winding start side used in Example 1. In this way, the tip was bent so as to be parallel to the bottom of the battery outer can 17, and other configurations were made in the same manner as in the case of the nonaqueous electrolyte secondary battery 10 A of Example 1.

[Production of Battery of Comparative Example 2]
As shown in FIG. 5, the nonaqueous electrolyte secondary battery 10 </ b> D of Comparative Example 2 is obtained by bending the winding-side negative electrode current collecting tab 12 e ₂ used in Example 1 once in a direction away from the gap 18 side. Further, it was folded back 180 °, and thereafter, it was produced in the same manner as in the case of the nonaqueous electrolyte secondary battery 10A of Example 1. Therefore, in the nonaqueous electrolyte secondary battery 10D of Comparative Example 2, the total thickness of the folded portion of the negative electrode current collecting tab 12e ₂ ′ is the same as that of the nonaqueous electrolyte secondary batteries 10A to 10C of Examples 1 and 2 and Comparative Example 1. In order to make the thickness of the negative electrode tab 12e ₂ equal to the thickness, the thickness of the negative electrode current collection tab 12e ₂ ′ is set to ½ of the thickness of the negative electrode current collection tab 12e ₂ .

[Measurement of internal resistance]
The internal resistance of the battery was measured by a 1 kHz AC method. The results are summarized in Table 1.

[Drum test results]
Furthermore, a drum test was performed on each of the nonaqueous electrolyte secondary batteries of Examples 1 and 2 and Comparative Examples 1 and 2 in which the initial internal resistance was measured as described above. The drum used was an octagon with a diameter of 23 cm and a length of 34 cm. Five battery samples were inserted into the drum, and rotation was continued at 60 rpm for 100 to 200 minutes. Then, in each case, the internal resistance value was measured, and the internal resistance value was 120, which was the initial measured value. The number of batteries increased by more than% was examined. The results are summarized in Table 1. The test was performed twice, for a total of ten.

From the results shown in Table 1, the following can be understood. That is, the batteries of Examples 1 and 2 and Comparative Example 1 had the same initial internal resistance value, but the battery of Comparative Example 2 had a larger initial internal resistance value than the others. The reason why such a phenomenon has occurred is that, in the battery of Comparative Example 2, the thickness of the negative electrode current collecting tab 12e ₂ ′ was determined so that the negative electrode current collecting tab 12e of Examples 1 and 2 and Comparative Example 1 was formed in order to form the folded portion. _This is because it is ½ of the thickness of 2.

  Further, according to the result of the drum test for 100 minutes, the batteries of Examples 1 and 2 and Comparative Example 2 did not change in the internal resistance in all the samples, but the battery of Comparative Example 1 had an increased internal resistance. As a result, 3 out of 10 were produced. Furthermore, according to the result of the drum test for 200 minutes, all the batteries of Example 2 did not change in internal resistance, but the batteries of Example 1 and Comparative Example 2 had 2 of 10 batteries with increased internal resistance. As a result, in the case of the battery of Comparative Example 1, an increase in internal resistance was observed as many as 6 out of 10 batteries.

Therefore, if an arc-shaped portion 12f having elasticity is formed between the joint portion with the battery outer can 17 on the negative electrode current collecting tab 12e ₁ attached to the winding start portion of the wound electrode body 14, vibration applied from the outside since like are absorbed by the arc-shaped portion 12f, it becomes difficult because of an external force applied to the joint portion between the battery outer can 17 and the anode current collector tab 12e ₂ can prevent metal fatigue, the internal resistance by extension It can be seen that the increase can be suppressed. Further, when comparing the results of Example 1 and Example 2, the negative electrode current collecting tab 12e ₂ attached to the winding start portion of the wound electrode body 14 is wound on the core exposed portion 12b on the winding start side of the electrode plate. It can be seen that the increase in internal resistance can be further suppressed by bonding to the outer side surface.

The nonaqueous electrolyte secondary battery 10D of Comparative Example 2 has the same tendency of increasing internal resistance as that of the nonaqueous electrolyte secondary battery 10A of Example 1, and therefore vibrations applied from the outside, etc. Is absorbed in the folded portion of the negative electrode current collecting tab 12e ₂ ′. However, since the thickness of the negative electrode current collecting tab 12e ₂ ′ of the nonaqueous electrolyte secondary battery 10D of Comparative Example 2 is thin, the initial internal resistance value is large. In this case, if the thickness of the negative electrode current collector tab 12e ₂ ′ is increased, the initial internal resistance value can be further reduced. However, the battery is increased by the thickness of the negative electrode current collector tab 12e ₂ ′. Since it leads to a decrease in capacity, it cannot be adopted immediately.

  In Examples 1 and 2, the negative electrode current collecting tab is formed on the exposed portion of the negative electrode core on the winding start side and the winding end side of the negative electrode plate. However, the present invention shows at least one current collecting tab. If the tab is formed on the exposed portion of the negative electrode core on the winding start side of the negative electrode plate, the above-described predetermined effects can be obtained. Moreover, in the said Example 1 and 2, although the example which made the shape part which has the elasticity of a current collection tab the arc-shaped part 12f was shown, it can also be set as a wave shape.

  In Examples 1 and 2, an example in which the shape portion having elasticity is formed on the current collecting tab on the winding start side of the negative electrode plate is shown. However, the arrangement of the negative electrode plate and the positive electrode plate is reversed. You may form the shape part which has elasticity in the positive electrode core exposure part of the winding start side of an electrode plate. However, in a non-aqueous electrolyte secondary battery typified by a lithium ion secondary battery, the charge capacity ratio (negative electrode charge capacity / positive electrode charge capacity) at a portion where the positive electrode plate and the negative electrode plate face each other is generally more than 1. For example, since the negative electrode plate is positioned on the innermost peripheral side, the negative electrode plate can be wound so that it is also positioned on the outermost peripheral side. The charge capacity ratio of the negative electrode plate can be easily made larger than the charge capacity ratio of the positive electrode plate.

FIG. 1A is a development view of a positive electrode plate used in the nonaqueous electrolyte secondary batteries of Examples and Comparative Examples, and FIG. 1B is a development view of the negative electrode plate. 1 is a longitudinal sectional view of a nonaqueous electrolyte secondary battery of Example 1. FIG. 3 is a longitudinal sectional view of the nonaqueous electrolyte secondary battery of Example 2. FIG. 4 is a longitudinal sectional view of the nonaqueous electrolyte secondary battery of Comparative Example 1. FIG. 5 is a longitudinal sectional view of a nonaqueous electrolyte secondary battery of Comparative Example 2. FIG. It is a longitudinal cross-sectional view in the middle of the assembly of the battery of a prior art example.

Explanation of symbols

10A to 10D: non-aqueous electrolyte secondary battery 11: positive electrode plate 11a: positive electrode core body 11b: positive electrode core body 11c: winding end side end portion 11d: positive electrode mixture layer 11e: positive electrode current collecting tab 12: negative electrode electrode plate 12a : the negative electrode substrate 12b: winding start side end portion 12c: winding end-side end portion 12d: the negative electrode mixture layer _{12e 1, 12e 2, 12e 2} ': negative electrode current collector tab 12f: arc-shaped portion 13: separator 14: winding Electrode bodies 15 and 16: Insulating plate 17: Battery outer can 18: Gap 19: Sealing plate 20: Positive terminal 21: Gasket

Claims (5)

A positive electrode plate having a positive electrode mixture layer formed on both sides of the positive electrode core and a negative electrode plate having a negative electrode mixture layer formed on both sides of the negative electrode core are wound with a separator interposed therebetween, and the center of the winding shaft Comprising a wound electrode body in which a gap is formed,
The wound electrode body is
On the winding start side of the one electrode plate, a core body exposed portion is formed, and a winding start portion current collecting tab is joined to the core body exposed portion on the winding start side,
The winding start portion current collecting tab is bent so as to contact the inner bottom portion of the battery outer can at a position corresponding to the gap portion of the wound electrode body, and is sealed to be joined to the inner bottom portion of the battery outer can. In batteries,
The said winding start part current collection tab is provided with the shape part which has elasticity in the said space | gap part of the said winding electrode body, The sealed battery characterized by the above-mentioned .
  A core exposed portion is also formed on the winding end side of the one electrode plate, a winding end current collecting tab is joined to the core exposed portion on the winding end side of the one electrode plate, and the winding end current collecting is performed. The tab is bent so as to contact the inner bottom portion of the battery outer can at a position corresponding to the gap portion of the wound electrode body, and is integrally joined together with the winding start current collecting tab and the inner bottom portion of the battery outer can. The sealed battery according to claim 1, wherein the battery is sealed.   2. The sealed battery according to claim 1, wherein the core body exposed portion on the winding start side of the one electrode plate is at least 1 round and less than 3 rounds of the outer circumference of the gap.   In the winding start portion current collecting tab, a portion including the elastic shape up to the joint portion with the battery outer can is joined to the winding outer surface of the core exposed portion on the winding start side surface of the one electrode plate. The sealed battery according to claim 1, wherein:   The sealed battery according to claim 1, wherein the sealed battery is a nonaqueous electrolyte secondary battery, and the one electrode plate is a negative electrode plate.

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