JP5503882B2 - Lithium ion battery - Google Patents

Description

  The present invention relates to a lithium ion battery, and in particular, an electrode group in which a positive electrode plate and a negative electrode plate are wound around a shaft core via a porous separator, and a protruding portion, a terminal portion, and a positive electrode lead piece are joined to the periphery. A positive pole column having a flange portion whose one surface side is in contact with one end surface of the shaft core, and a flange portion in which the projecting portion, the terminal portion, and the negative electrode lead piece are joined to the peripheral edge and one surface side is in contact with the other end surface of the shaft core; The present invention relates to a lithium ion battery including a negative electrode pole having

  Lithium ion batteries have high voltage and high energy density, and are excellent in storage performance and low-temperature operation performance, and are widely used in portable electric products for consumer use. In addition, research and development for increasing the size of this battery and using it as a nighttime power storage device for electric vehicles and homes are actively conducted.

  Such a large lithium ion battery (for example, having a capacity of 5 Ah or more) generally has a positive electrode plate using a lithium manganese composite oxide as an active material and a negative electrode plate using a carbon material as an active material through a porous separator. The electrode group wound around the shaft axis made of the resin-like resin is provided, and the electrode group is infiltrated with the non-aqueous electrolyte. Some types of batteries include a positive electrode pole and a negative electrode pole at positions opposite to each other via an electrode group. The positive pole is composed of a positive electrode lead piece led out from the positive electrode plate and joined to the periphery, one side of which is in contact with one end surface of the shaft core, a protrusion inserted into the shaft core, and a side opposite to the protrusion A terminal portion exposed from the battery lid is included, and the flange portion, the protruding portion, and the terminal portion are integrally formed. On the other hand, the negative electrode pole column has a negative electrode lead piece led out from the negative electrode plate joined to the peripheral edge, one side of which is in contact with the other end surface of the shaft, and a portion opposite to the protruding portion of the positive electrode pole in the shaft core. An inserted protrusion and a terminal part exposed from the battery lid on the opposite side of the protrusion are provided, and the flange part, the protrusion part, and the terminal part are integrally formed. In addition, in a battery (for example, an electric vehicle battery) that requires high output characteristics, a lead piece formed by cutting out a current collector is joined to the periphery of the collar portion in order to reduce internal resistance.

  For example, when an abnormality occurs in the battery control unit or the charger during charging and the battery is in an abnormal state such as overcharging, the lithium ion battery rises in battery temperature, in particular, the separator rises due to the temperature rise in the center of the electrode group. When dissolved, a short circuit occurs, and the internal pressure of the battery rises abnormally due to the decomposition gas of the electrolyte.

  In order to prevent this problem, the internal pressure rise due to cracked gas has been used to operate the cleaving valve and current shutoff valve provided on the battery can to reduce the internal pressure before the battery ruptures or Measures are taken such as cutting off the current before starting (see, for example, Patent Documents 1 and 2). Further, in order to suppress an increase in battery temperature, for example, a technique for dissipating heat inside the battery to the outside of the battery by disposing a metal shaft core at the center of winding of the electrode group is disclosed (for example, (See Patent Document 3).

Japanese Patent Laid-Open No. 11-219692 JP 2005-108503 A Japanese Patent Laid-Open No. 10-92469

  In the case of a large-sized lithium ion battery, since the amount of nonaqueous electrolyte used is large and the behavior of the battery when the battery is abnormal becomes severe, ensuring the safety of the battery is required. In addition, when a metal shaft core is arranged at the center of winding of the electrode group as in the prior art, only a separator exists between the metal shaft core and the positive electrode plate and the negative electrode plate. There is a possibility that the separator breaks at the start of rotation and short-circuits. Furthermore, since the metal shaft core is made of a material different from that of the separator, it is difficult to integrate the winding tip of the separator and the metal shaft core by heat welding, and it is difficult to align the positive electrode plate, the negative electrode plate and the separator. There is a risk of winding misalignment during winding.

  An object of the present invention is to provide a lithium ion battery that can suppress a temperature rise when the battery is abnormal and prevent winding deviation during winding.

In order to solve the above-mentioned problems, the present invention provides a lithium ion battery, in which a positive electrode plate using a lithium manganese composite oxide as an active material and a negative electrode plate using a carbon material as an active material are cylindrically interposed via a porous separator. An electrode group wound around a metal-made shaft core, a protrusion inserted into the shaft core, a terminal portion exposed from the battery lid on the opposite side of the protrusion, and the protrusion and the terminal portion And a positive electrode pole column having a flange portion in which a positive electrode lead piece led out from the positive electrode plate is joined to a peripheral edge and one surface abuts against one end surface of the shaft core, and the positive electrode The pillar is a projecting portion inserted into the shaft core on the opposite side through the shaft core, a terminal portion exposed from the battery lid on the opposite side of the projecting portion, and between the projecting portion and the terminal portion. It is integrally formed, and the negative electrode lead piece led out from the negative electrode plate is joined to the peripheral edge to one side A negative pole pole having a flange portion that contacts the other end face of the shaft core, and the shaft core is made of aluminum or aluminum alloy of the same kind as the positive pole pole or of the same kind of material as the negative pole pole. It is made of copper or a copper alloy, and its surface is coated with a member of the separator and the same material except for an end face of the side abutting the flange portion of the pole columns of the axis of the same kind material among the positive and negative gulp pillar the thickness of the coating is characterized in der Rukoto than 0.3 mm.

In the present invention, the shaft core is made of aluminum or aluminum alloy of the same kind as that of the positive electrode pole column, or made of copper or copper alloy of the same kind of material as that of the negative electrode pole pole, and has high thermal conductivity. Further, the surface of the shaft core is coated with a member made of the same material as that of the separator except for the end surface of the positive and negative electrode poles on the side contacting the collar portion of the same kind of material as the shaft core. That is, when the material of the shaft core is made of aluminum or an aluminum alloy, its surface is coated with a member made of the same material as that of the separator except for one side end face that comes into contact with the collar portion of the positive electrode pole. In the case of the product, its surface is coated with a member made of the same material as the separator except for the other end face that comes into contact with the collar portion of the negative electrode pole , and the thickness of this coating is set to 0.3 mm or more. .

According to the present invention, the shaft core is made of a metal having a high thermal conductivity, which is the same material as any of the positive and negative electrode pole columns, and the end surface on the side contacting the flange of the pole column of the same material as the shaft core among the positive and negative electrode pole columns. Is not coated, the temperature at the center of winding of the electrode group when the battery is abnormal is conducted from the shaft core to the terminal part outside the battery cover through the pole part of the pole, and the heat inside the battery Can be radiated to the outside of the battery, so that short circuit due to dissolution of the separator and increase in internal pressure due to decomposition of the non-aqueous electrolyte can be suppressed, and the outer peripheral surface of the shaft core is coated with a member made of the same material as the separator. Therefore, it is easy to integrate the winding tip of the separator and the shaft core by heat welding, the positioning of the positive electrode plate, the negative electrode plate and the separator is easy, and the winding deviation at the time of winding the electrode group can be prevented . Shaft core coating thickness 0.3 mm or more, it is possible to prevent a short circuit between the shaft core and the projecting portion of the positive and negative electrode poles, and the surface of the shaft core is a pole column made of the same material as the shaft core of the positive and negative electrode pole columns. when coated with members of the same material as the separator except for the end surface of the side the flange portion abuts, and in the case of performing the coating in grooves pickled, Ru can be improved in productivity.

In the present invention, the shaft core is made of the same material aluminum or aluminum alloy as the positive electrode pole column or the same material as the negative electrode pole column copper or copper alloy, and the shaft core material is made of aluminum or aluminum alloy. The surface is coated with a member made of the same material as the separator except for one end face that abuts the flange of the positive electrode pole. If the surface is made of copper or copper alloy, the surface is in contact with the negative electrode pole It may be coated with a member made of the same material as the separator except for the side end face. The material of the separator and the axial center of the coating, for example, may be a resin of polyolefin. Furthermore, in order to prevent winding misalignment, the electrode group is wound by integrating the winding leading end portion and the shaft core of the separator by heat welding at the beginning of winding and aligning the positions of the positive electrode plate, the negative electrode plate and the separator. It is desirable that

According to the present invention, the shaft core is made of a metal having a high thermal conductivity, which is the same material as any of the positive and negative electrode pole columns, and the end surface on the side contacting the flange of the pole column of the same material as the shaft core among the positive and negative electrode pole columns. Is not coated, the battery internal heat can be dissipated to the outside by the terminal part exposed to the outside when the battery is abnormal, so the internal pressure rises due to short circuit due to the dissolution of the separator or decomposition of the non-aqueous electrolyte Since the peripheral surface of the shaft core is coated with the same material as the separator, it is easy to integrate the winding tip of the separator and the shaft core by heat welding. Winding misalignment can be prevented , and the coating thickness of the shaft core is 0.3 mm or more, so that a short circuit between the shaft core and the projecting portion of the positive and negative electrode pole columns can be prevented. The surface of the positive and negative pole pole When coated with members of the separator and the same material except for an end face of the side abutting the flange portion of the pole core and the same type material, in the case of this coating in the groove pickled, it is possible to improve the productivity Can be obtained.

It is sectional drawing of the lithium ion battery of embodiment which can apply this invention. It is sectional drawing which shows typically the state at the time of the winding start of the electrode group of the lithium ion battery of embodiment.

  Hereinafter, an embodiment in which the present invention is applied to a lithium ion battery for a genuine electric vehicle (PEV) will be described with reference to the drawings.

(Overview)
As shown in FIG. 1, the lithium ion battery 20 of the present embodiment includes a bottomless cylindrical battery container 5 and two disk-shaped battery lids 4 disposed at both ends of the battery container 5 as casings. Have. In the casing, an electrode group 6 in which a positive electrode plate and a negative electrode plate are arranged via a separator around a hollow cylindrical shaft core 11 is infiltrated and accommodated in a non-aqueous electrolyte described later.

  The lithium ion battery 20 also includes a positive electrode pole 13 made of aluminum and a negative electrode pole 13 ′ made of copper arranged at positions opposite to each other in the vertical direction via the electrode group 6. The positive electrode pole 13 has a collar portion in which the positive electrode lead piece 9 led out from the positive electrode plate is joined to the periphery, and one surface side (bottom surface side in FIG. 1) abuts one side end surface (upper end surface in FIG. 1) of the shaft core 11. 7. A projecting portion 18 inserted into the shaft core 11 and a terminal portion 1 exposed from the battery lid 4 on the opposite side of the projecting portion 18 are provided. The flange portion 7, the projecting portion 18 and the terminal portion 1 are integrally formed. Has been. On the other hand, the negative electrode pole column 13 ′ has a flange portion 7 ′ in which a negative electrode lead piece 9 ′ led out from the negative electrode plate is joined to the peripheral edge and one surface side (upper surface side in FIG. 1) abuts against the other end surface of the shaft core 11. There is a protrusion 18 ′ inserted into the shaft core 11 on the side opposite to the protrusion 18 of the positive electrode pole 13, and a terminal portion 1 ′ exposed from the battery lid 4 on the side opposite to the protrusion 18 ′. The flange portion 7 ′, the protruding portion 18 ′, and the terminal portion 1 ′ are integrally formed.

  The shaft core 11 is made of aluminum of the same material as that of the positive electrode pole column 13, and the surface thereof is separated from the separator 24 (see FIG. 1) except for one end surface (upper end surface in FIG. 1) that contacts the flange portion 7 of the positive electrode pole column 13. 2) and the same material (polyolefin resin as will be described later).

(Production procedure)
Hereinafter, with reference to FIG. 1 and FIG. 2, the lithium ion battery 20 of the present embodiment will be described in more detail, and the manufacturing procedure of the lithium ion battery 20 will be described.

(Preparation of positive electrode plate)
A positive electrode plate 22 (see FIG. 2) constituting the electrode group 6 was produced by the following method. Lithium manganate (LiMn ₂ O ₄ ) powder as a positive electrode active material, flake graphite (average particle size: 20 μm) as a conductive agent, and polyvinylidene fluoride (PVDF) as a binder are mixed, and this mixture After adding N-methyl-2-pyrrolidone (NMP) as a dispersion solvent, a slurry was prepared by kneading. This slurry was applied to both surfaces of an aluminum foil (positive electrode current collector) having a thickness of 20 μm to form a positive electrode mixture layer. When applying the slurry, an uncoated portion having a width of 50 mm was left on one of the side edges with respect to the longitudinal direction of the aluminum foil. Thereafter, drying, pressing and cutting were performed to obtain a positive electrode plate having a width of 389 mm and a length of 5100 mm. The thickness of the positive electrode mixture layer (however, the thickness of the current collector is not included) was 275 μm, and the amount of the positive electrode active material applied per one side of the current collector was 350 g / m ² .

  A not-applied portion having a width of 50 mm formed on the positive electrode plate was cut out and a part thereof was removed to form a rectangular (comb-shaped) portion, which was used as a positive electrode lead piece 9 for current collection. The width of the positive electrode lead piece 9 was about 10 mm, and the interval between the adjacent positive electrode lead pieces 9 was about 20 mm.

(Preparation of negative electrode plate)
On the other hand, the negative electrode plate 23 (see FIG. 2) constituting the electrode group 6 was produced by the following method. Artificial graphite powder as a negative electrode active material and PVDF as a binder were mixed, NMP was added as a dispersion solvent to this mixture, and then kneaded to prepare a slurry. This slurry was applied to both surfaces of a rolled copper foil (negative electrode current collector) having a thickness of 10 μm to form a negative electrode mixture layer. When applying the slurry, an uncoated portion having a width of 50 mm was left on one side edge with respect to the longitudinal direction of the copper foil. Thereafter, drying, pressing and cutting were performed to obtain a negative electrode plate having a width of 395 mm and a length of 5290 mm. The thickness of the negative electrode mixture layer (not including the current collector thickness) was 201 μm, and the negative electrode active material coating amount per side of the current collector was 130.8 g / m ² .

  A non-coated portion with a width of 50 mm formed on the negative electrode plate was cut out and a part thereof was removed to form a rectangular portion, which was used as a negative electrode lead piece 9 'for current collection. The width of the negative electrode lead piece 9 ′ was about 10 mm, and the interval between the adjacent negative electrode lead pieces 9 ′ was about 20 mm.

  Also in the width direction of the positive electrode plate 22 and the negative electrode plate 23, the width of the negative electrode active material application portion is set so that no positional deviation occurs between the positive electrode active material application portion and the negative electrode active material application portion. The width of the coated portion of the positive electrode active material was larger.

(Production of electrode group)
The positive electrode plate 22 and the negative electrode plate 23 were wound in a state where the positive electrode plate 22 and the negative electrode plate 23 were sandwiched between two porous separators 24 mainly composed of a polyolefin-based polypropylene having a thickness of 36 μm, thereby preparing the electrode group 6. As described above, the shaft core 11 made of the same material (made of aluminum) as the positive electrode pole 13 is disposed at the center of winding of the electrode group 6, and as shown in FIG. Except for the upper end face of the shaft core 11, a material mainly composed of polyolefin-based polypropylene, which is the same material as the separator 24, is coated. The coating thickness was 0.3 mm or more.

  In winding, the tip portion 21 of the separator 24 and the shaft core 11 are first integrated by thermal welding, and the positions of the positive electrode plate 22, the negative electrode plate 23, and the separator 24 are aligned to reduce the possibility of winding misalignment. These positive electrode plate 22, negative electrode plate 23, and separator 24 were wound. The positive electrode lead piece 9 and the negative electrode lead piece 9 ′ were arranged so as to be located on the opposite side of the electrode group 6. By cutting the positive electrode plate 22, the negative electrode plate 23, or the separator 24 at an appropriate length during winding, the diameter of the electrode group 6 was set to 63.6 ± 0.1 mm.

(Production of battery)
The positive electrode lead pieces 9 led out from the positive electrode plate 22 are collected and folded in a bundled state, and then brought into contact with the peripheral edge of the flange portion 7 of the positive electrode pole column 13, so that the positive electrode lead piece 9 and the flange portion 7 The peripheral edge was electrically connected by welding (joining) using an ultrasonic welding apparatus. Similarly, for the negative electrode plate, the negative electrode lead piece 9 ′ and the peripheral edge of the flange 7 ′ of the negative electrode pole column 13 ′ were electrically connected by ultrasonic welding.

  Thereafter, the flange 7 of the positive electrode pole 13, the flange 7 ′ of the negative electrode pole 13 ′, and the entire outer peripheral surface of the electrode group 6 were covered with an insulating coating 8. As the insulating coating 8, a polyimide adhesive tape having one side coated with an adhesive made of hexamethacrylate was used. After adjusting the number of turns of the adhesive tape so that the outer peripheral portion of the electrode group 6 is covered with the insulating coating 8 and slightly smaller than the inner diameter of the stainless steel battery container 5, the electrode group 6 is inserted into the battery container 5. did. In addition, the battery container 5 of this embodiment has an outer diameter of 67 mm and an inner diameter of 66 mm.

  Next, a second ceramic washer 3 ′ was fitted into each of the tips of the (positive electrode) terminal portion 1 and the (negative electrode) terminal portion 1 ′ in a portion that contacts the outer surface of the battery lid 4. Then, the flat first ceramic washer 3 was placed on the battery lid 4, and each of the terminal portion 1 and the terminal portion 1 ′ was passed through the first ceramic washer 3.

Thereafter, the periphery of the battery lid 4 was fitted into the opening of the battery container 5, and the entire contact portion between the battery lid 4 and the battery container 5 was laser welded. At this time, the terminal portion 1 and the terminal portion 1 ′ protrude outside through a hole formed in the center of the battery lid 4. Then, a metal washer 14 smoother than the bottom surface of the metal nut 2 was fitted into each of the terminal portion 1 and the terminal portion 1 ′ so as to contact the first ceramic washer 3. The battery lid 4 on one side (upper side in FIG. 1) is provided with a cleavage valve 10 that cleaves as the internal pressure of the battery increases, and the cleavage pressure is set to 13 to 18 kg / cm ² . Note that the lithium ion battery 20 of the present embodiment is not provided with a current interruption mechanism that operates in response to a rise in the pressure inside the battery unlike a so-called small-sized consumer lithium ion battery.

  The nut 2 is screwed to the terminal portion 1 and the terminal portion 1 ′, respectively, and the battery lid 4 is connected to the flange portion 7 and the nut 2 via the metal washer 14, the second ceramic washer 3 ′, and the first ceramic washer 3. Tightened between and fixed. The tightening torque value at this time was 6.86 N · m. By compressing a rubber (EPDM) O-ring 16 interposed between the back surface of the battery lid 4 and the protruding portion 18 at the time of tightening, the power generation elements and the like inside the battery container are shielded from the outside air.

Next, after injecting a predetermined amount of non-aqueous electrolyte into the battery container 5 from the liquid injection port formed in the battery lid 4 on the other side (lower side in FIG. 1), the liquid injection port is sealed with a liquid injection plug 15. The cylindrical lithium ion battery was completed by stopping. In addition, after mixing ethylene carbonate (EC) and dimethyl carbonate (DMC) at a volume ratio of 2: 3, 1 mol / liter of lithium hexafluorophosphate (LiPF ₆ ) is dissolved in the non-aqueous electrolyte as an electrolyte. What was done was used.

(Effects etc.)
Next, effects and the like of the lithium ion battery 20 of the present embodiment will be described.

  In the lithium ion battery 20 of the present embodiment, the shaft core 11 is made of aluminum of the same material as the positive electrode pole column 13 and has high thermal conductivity, and the surface of the shaft core 11 is on the flange portion 7 of the positive electrode pole column 13. It is coated with a polyolefin-based polypropylene made of the same material as the separator 24 except for the end face on the abutting side. For this reason, the temperature of the winding center part of the electrode group 6 is thermally conducted from the shaft core 11 to the terminal part 1 exposed to the outside of the battery cover 4 through the collar part 7 of the positive electrode pole 13, and the heat inside the battery is transferred to the battery. It can dissipate heat to the outside. Therefore, when the battery is abnormal, it is possible to suppress a short circuit due to the dissolution of the separator and an increase in internal pressure due to the decomposition of the nonaqueous electrolytic solution.

  Further, in the lithium ion battery 20, the surface of the shaft core 11 is coated with a polyolefin-based polypropylene made of the same material as the separator 24 except for the end face on the side in contact with the flange portion 7 of the positive electrode pole 13. Therefore, the winding tip of the separator 24 and the shaft core 11 can be easily integrated by thermal welding, the positioning of the positive electrode plate, the negative electrode plate, and the separator is easy (see FIG. 2). Misalignment can be prevented.

  Further, in the lithium ion battery 20, since the heat inside the battery can be radiated to the outside of the battery even at normal times other than when the battery is abnormal, a positive electrode active material or the like that easily deteriorates at high temperatures (for example, 50 ° C.). Deterioration can be prevented.

  Further, in the lithium ion battery 20, since the coating thickness of the shaft core 11 is 0.3 mm or more, a short circuit between the shaft core 11 and the protruding portion 18 'of the negative electrode pole 13' can be prevented. Considering the reliability of vibration and aging when the lithium ion battery 20 is mounted on the vehicle, the protrusion 18 ′ of the negative electrode pole 13 ′ is also coated, or other parts are interposed between the shaft 11 and the protrusion 18 ′. An insulating member may be interposed.

In the present embodiment, the shaft core 11 is made of aluminum which is the same material as the projecting portion 18, and the shaft core 11 is fitted to the projecting portion 18. However, the present invention is limited to this. Instead, for example, the same effect can be obtained by using a (same kind) material such as an aluminum alloy. Furthermore, the material of the shaft core is made of the same material as that of the copper negative electrode pole 13 ', such as copper or copper alloy, and the lower end surface of the copper resin coated shaft core is in contact with the flange portion 7' of the negative electrode pole column 13 '. You may make it make it. In this case, axial, and it may be coated with a polypropylene polyolefin of the same material as the separator 24 except the lower end surface of the copper resin coated axis.

  Moreover, in this embodiment, although the example which uses a polypropylene resin for the coating of the shaft 11 made from aluminum was shown, this invention is not limited to this, For example, polyolefin-type, such as polyethylene and polytetrafluoroethylene Any material can be used as long as it can be welded to the aluminum shaft core 11 without being dissolved in the non-aqueous electrolyte solution, such as the above materials and polyamide resin. In addition, what is necessary is just to use what does not melt | dissolve in a flame retardant, when the flame retardant is mixed in the non-aqueous electrolyte.

  Further, in the present embodiment, an example is shown in which the surface of the shaft core 11 is coated with a polyolefin-based polypropylene of the same material as the separator 24 except for the upper end surface on the side in contact with the flange portion 7 of the positive electrode pole 13. However, the present invention is not limited to this, and for example, the surface of the shaft core 11 in the vicinity of the upper end face may be removed from the coating. Such an embodiment can improve productivity when coating the shaft core 11 by so-called soaking.

  Further, in this embodiment, lithium manganate is exemplified as the positive electrode active material and graphite is exemplified as the negative electrode active material, but the present invention is not limited to these. For example, the positive electrode active material may be a lithium transition metal double oxide such as lithium cobaltate or lithium nickelate, or may be a composite oxide containing a plurality of types of transition metals. In addition, a material in which a part of lithium or manganese is substituted or doped with an element other than these may be used. Examples of the negative electrode active material that can be used other than the present embodiment include carbon materials such as amorphous carbon, natural graphite, and coke, and the shape thereof is also spherical, flake shaped, fibrous, It is not particularly limited to a lump shape.

In the present embodiment, an example in which a non-aqueous electrolyte solution in which 1 mol / liter of LiPF ₆ is dissolved in a mixed solvent of EC and DMC is used is shown, but the present invention is not limited to this. A general lithium salt can be used as an electrolyte and dissolved in an organic solvent. There are no particular limitations on the lithium salt or organic solvent used. For example, LiC1O ₄ , LiAsF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, or a mixture thereof may be used as the electrolyte. Examples of the organic solvent include propylene carbonate, diethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3- Dioxolane, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propionitrile, or a mixed solvent of two or more of these may be used. Also, the mixing ratio is not limited.

  Next, examples of the lithium ion battery 20 manufactured according to the present embodiment will be described. In addition, it describes together about the battery of the comparative example produced for the comparison.

(Example)
In Example 1, an aluminum shaft core 11 coated with polypropylene except for the upper end surface was disposed at the winding center of the electrode group 6, and the upper end surface of the shaft core 11 was brought into contact with the bottom surface of the flange portion 7. A battery was produced. In Example 2, a copper shaft core 11 coated with polypropylene except for the lower end surface is disposed at the winding center of the electrode group 6, and the lower end surface of the shaft core 11 is in contact with the upper surface of the flange portion 7 ′. A battery was produced.

(Comparative example)
In Comparative Example 1, a battery was produced in the same manner as in Example 1 except that an uncoated polypropylene shaft core 11 was used at the winding center of the electrode group 6.

(test)
The following measurements and tests were performed on the batteries of the examples and comparative examples. After charging in a greenhouse, the battery was discharged and the discharge capacity was measured. The charging conditions were 4.1V constant voltage, limiting current 50A, 5 hours. The discharge conditions were a constant current of 100A and a final voltage of 3V. Thereafter, a continuous charge test was performed from 100% to 150% SOC at a constant current of 50A at room temperature, and the behavior of the battery when the SOC reached 150% was observed. The results are shown in Table 1.

  As shown in Table 1, in the battery of Comparative Example 1 using a polypropylene shaft core, gas was released from the cleavage valve after the cleavage valve was opened at SOC 150%. For this reason, in the battery of Comparative Example 1, the heat radiation from the center of the electrode group 6 to the outside of the battery is poor, the temperature at the center of the electrode group 6 rises, the electrolyte solution decomposes, and the decomposition gas of the electrolyte solution It is considered that cleavage of the cleavage valve and gas ejection occurred because the pressure in the battery increased.

  On the other hand, an aluminum shaft core 11 coated with polypropylene except for the upper end surface is disposed at the winding center of the electrode group 6, and the upper end surface of the shaft core 11 is brought into contact with the bottom surface of the flange portion 7. In Example 1 and the winding center of the electrode group 6, a copper shaft core 11 coated with polypropylene excluding the lower end surface is disposed, and the lower end surface of the shaft core 11 is brought into contact with the upper surface of the flange portion 7 '. In the battery of Example 2 that was in contact with each other, no gas ejection was observed at the SOC of 150%. Therefore, in the lithium ion batteries 20 of Example 1 and Example 2, heat dissipation from the central part of the electrode group 6 to the outside of the battery is good, and the temperature rise at the central part of the electrode group 6 is moderate. It is considered that the decomposition of the electrolyte solution in the sample is suppressed.

  Since the present invention provides a lithium ion battery that can suppress a temperature rise at the time of battery abnormality and can prevent winding deviation at the time of winding, it contributes to the manufacture and sale of lithium ion batteries, and thus can be used industrially. Have sex.

DESCRIPTION OF SYMBOLS 1, 1 'Terminal part 6 Electrode group 7, 7' collar 11 Axle core 13 Positive electrode pole column 13 'Negative electrode pole column 18, 18' Protrusion part 20 Lithium ion battery 22 Positive electrode plate 23 Negative electrode plate 24 Separator

Claims (4)

An electrode group in which a positive electrode plate using a lithium manganese composite oxide as an active material and a negative electrode plate using a carbon material as an active material are wound around a cylindrical metal shaft core via a porous separator;
The protrusion part inserted into the shaft core, the terminal part exposed from the battery lid on the opposite side of the protrusion part, and the protrusion part and the terminal part are integrally formed and are led out from the positive electrode plate. A positive electrode pole piece having a flange portion bonded to the peripheral edge and having a flange portion in contact with one end surface of the shaft core;
The positive electrode pole is a projecting portion inserted into the shaft core on the opposite side through the shaft core, a terminal portion exposed from the battery lid on the opposite side of the projecting portion, the projecting portion and the terminal portion, A negative electrode pole having a negative electrode lead piece led out from the negative electrode plate and having a flange portion whose one side is in contact with the other end surface of the shaft;
With
The shaft core is made of aluminum or aluminum alloy of the same kind as the positive electrode pole column, or made of copper or copper alloy of the same kind of material as the negative pole pole, and the surface thereof is made of the same kind material as the shaft core of the positive and negative pole poles. of which is coated with a member of the separator and the same material to the flange portion except for the end face of the side abutting the pole columns, lithium-ion batteries the thickness of the coating is characterized in der Rukoto than 0.3 mm.   The shaft core is made of aluminum or aluminum alloy of the same material as the positive electrode pole column or made of copper or copper alloy of the same material as the negative electrode pole column, and when the material of the shaft core is made of aluminum or aluminum alloy, The surface is coated with a member made of the same material as that of the separator except for one end face that abuts the flange of the positive electrode pole. When the surface is made of copper or a copper alloy, the surface is in contact with the negative electrode pole. The lithium ion battery according to claim 1, wherein the lithium ion battery is coated with a member made of the same material as that of the separator except for the other end face in contact therewith.   3. The lithium ion battery according to claim 1, wherein the separator and the shaft core are made of a polyolefin-based resin. 4.   The electrode group is wound by integrating the winding leading end portion of the separator and the shaft core by heat welding at the beginning of winding, and aligning the positions of the positive electrode plate, the negative electrode plate, and the separator. The lithium ion battery according to claim 1, wherein the lithium ion battery is provided.

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