JP2013089441A - Electrode group for battery and battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize winding slippage or exfoliation of a mixture layer at the time of winding by configuring an electrode group for battery to be wound so as to touch a separator having different coefficients of friction on both sides or a positive electrode plate and a negative electrode plate, which has a larger coefficient of friction, and to provide a nonaqueous secondary battery with high safety by minimizing heat generation due to internal short circuit by using the electrode group.SOLUTION: The electrode group for battery is configured to be wound so as to touch a separator 14 having different coefficients of friction on front and rear sides or a positive electrode plate 12 and a negative electrode plate 13, which has a larger coefficient of friction.

Description

  The present invention relates to a battery electrode group represented by a lithium ion battery and a battery using the same.

In recent years, non-aqueous secondary batteries, which are widely used as power sources for portable electronic devices, are typified by lithium secondary batteries, and use a carbonaceous material that can occlude and release lithium as a negative electrode active material, and a positive electrode active material. In addition, a composite oxide of lithium and a transition metal such as LiCoO ₂ is used as an active material, thereby realizing a non-aqueous secondary battery having a high potential and a high discharge capacity. However, with the recent increase in functionality and miniaturization of electronic devices and communication devices, it is desired to further reduce the size and capacity of non-aqueous secondary batteries.

  Here, as an electrode plate that is a power generation element for realizing a high-capacity non-aqueous secondary battery, a mixture paint obtained by coating each constituent material with a positive electrode plate and a negative electrode plate is applied on a current collector. Then, after drying, a method of compressing to a prescribed thickness by a press or the like is used. By filling and pressing with a larger amount of active material, the active material density becomes higher, and a further increase in capacity becomes possible.

  In addition, a battery case made of a metal such as stainless steel, nickel-plated iron, or aluminum made of an electrode group in which the above-described positive electrode plate and negative electrode plate are spirally wound through a separator as a porous insulator Then, after pouring a non-aqueous electrolyte into the battery case, a sealing plate is hermetically fixed to the opening end of the battery case to form a non-aqueous secondary battery. In addition, development of a flat laminate battery using an exterior body such as an aluminum laminate film instead of a metal case is also progressing.

  By the way, while increasing capacity, safety measures should be emphasized, especially when a non-aqueous secondary battery suddenly rises in temperature due to an internal short circuit between the positive and negative plates, leading to thermal runaway. Therefore, there is a strong demand for improving the safety of non-aqueous secondary batteries. In particular, a large-sized, high-power non-aqueous secondary battery has a high probability of thermal runaway, and thus needs to be improved to improve safety, such as reducing the probability of occurrence.

  As described above, the cause of the internal short circuit of the non-aqueous secondary battery is that the electrode plate is used when the electrode group is configured in addition to the contamination of the non-aqueous secondary battery, and further when the battery is charged / discharged. It is conceivable that the electrode plate breaks due to the stress applied to. More specifically, when constituting the electrode group by winding in a spiral shape or compression molding into a flat shape, a large stress is applied to the positive electrode plate, the negative electrode plate, and the separator, which are constituent elements, in a portion having a small curvature radius, The mixture layer is broken from the one having the smallest elongation rate due to the dropping of the mixture layer or the difference in the elongation rate among the components at this time.

  Further, when winding in a spiral shape, it is conceivable that the positional relationship between the electrode plate and the separator is shifted and the electrode plate is exposed. More specifically, after winding the electrode plate and the separator on the winding core and winding it in a spiral shape, when removing from the winding core, the contact portion between the winding core and the separator has a large friction, so that only the contact portion is wound. Since it remains on the core, a phenomenon occurs in which the electrode plate in the vicinity thereof is not covered with the separator, or the central portion of the electrode group protrudes from the wound body, and the body does not form the electrode group.

Therefore, in order to suppress such thermal runaway due to a short circuit, for example, the coefficient of friction with the surface of the negative electrode plate is defined, and even if the negative electrode plate expands, the surface layer portion of the separator does not collapse and the cycle characteristics deteriorate. A separator that can suppress the above has been proposed (see, for example, Patent Document 1).

  Moreover, in order to suppress the deviation | shift at the time of such extraction at the time of winding, the winding method which makes a surface with a small friction coefficient contact a core is proposed (for example, refer patent document 2).

  Similarly, in order to remove the wound body more smoothly from the core, there has been proposed a method of selecting an optimum value by defining a friction coefficient by surface treatment of the core (for example, Patent Document 3).

International Publication No. 2008/059806 International Publication No. 2008/143005 JP 2009-70726 A

  However, the above-described prior art disclosed in Patent Document 1 merely defines the relative coefficient of friction between the negative electrode plate and the separator, and does not take any measures against a deviation or the like when the core is pulled out.

  Further, in the prior art of Patent Document 2, a winding method in which a surface with a small friction coefficient is brought into contact with the core, but even when a surface with a relatively small friction coefficient is brought into contact with the core, the friction coefficient at the time of extraction is sufficient. However, it cannot be said that the problem is surely solved.

  Moreover, although the friction coefficient by the surface treatment of a core is defined in patent document 3, the relationship with the friction coefficient with the separator which contacts is unknown, and a subject may not be solved reliably.

  In the present invention, when a positive electrode plate and a negative electrode plate are wound on both sides via a separator having a different friction coefficient to form an electrode group, the surface having a large friction coefficient is separated from the surface of the negative electrode plate and the positive electrode plate. By making contact with the one with the larger coefficient, it is possible to suppress the displacement and dropping of the mixture at the time of manufacture, and to suppress the buckling due to the expansion and contraction of the electrode plate due to repeated charge and discharge. It aims at providing the electrode group for batteries with high.

  In order to solve the above-described conventional problems, the battery electrode group of the present invention includes a positive electrode plate and a negative electrode plate having different friction coefficients on the surface, and the positive electrode plate and the negative electrode plate are interposed via separators having different friction coefficients on both sides. A battery electrode group formed by winding the separator so that a surface having a large friction coefficient of the separator is wound so as to be in contact with a surface having a larger coefficient of friction between the positive electrode plate and the negative electrode plate. Is.

According to the battery electrode group of the present invention, a battery electrode comprising a positive electrode plate and a negative electrode plate having different surface friction coefficients, and the positive electrode plate and the negative electrode plate are wound on both sides via separators having different friction coefficients. In the group, the surface of the separator having a large coefficient of friction was wound so as to be in contact with the positive electrode plate and the negative electrode plate having the larger coefficient of friction on the surface, thereby exposing the electrode plate due to the deviation of the separator during manufacture. It is possible to suppress the internal short circuit by suppressing the dropping of the mixture layer when it is formed into a flat shape. In addition, by improving the adhesion between the electrode plate and the separator in the wound electrode group, the stress applied to the electrode group during volume increase due to expansion of the negative electrode plate is suppressed by lithium intercalated with the negative electrode plate As a result, it is possible to suppress buckling of the electrode plate and to suppress breakage of the electrode plate. In addition, by using this electrode group, it is possible to provide a battery with high safety by suppressing internal short circuit due to mixture dropping, fracture or buckling of the electrode plate.

1 is a partially cutaway perspective view of a rectangular non-aqueous secondary battery according to a first embodiment of the present invention. Sectional drawing of the battery electrode group in the 1st Embodiment of this invention. Schematic which shows the positive electrode plate in the 1st Embodiment of this invention, a negative electrode plate, and a separator. The schematic diagram shape | molded in the flat shape in the 1st Embodiment of this invention Schematic diagram in which the positive electrode plate, the negative electrode plate, and the separator in the first embodiment of the present invention are inserted into the winding core and wound. (A) Schematic diagram molded into a flat shape in the first embodiment of the present invention (b) Enlarged sectional view of the main part of a battery electrode group molded into a conventional flat shape (c) First implementation of the present invention The expanded sectional view of the principal part of the battery electrode group shape | molded in the flat shape in the form Schematic which shows the positive electrode plate, negative electrode plate, and separator in the 2nd Embodiment of this invention. Schematic diagram in which the positive electrode plate, the negative electrode plate, and the separator in the second embodiment of the present invention are inserted into the winding core and wound. (A) Schematic diagram formed into a flat shape in the second embodiment of the present invention (b) Enlarged sectional view of the main part of a battery electrode group formed into a conventional flat shape (c) Second embodiment of the present invention The expanded sectional view of the principal part of the battery electrode group shape | molded in the flat shape in the form Schematic which shows the positive electrode plate, negative electrode plate, and separator in other embodiment of this invention.

  In the first aspect of the present invention, a battery electrode comprising a positive electrode plate and a negative electrode plate having different friction coefficients on the surface, wherein the positive electrode plate and the negative electrode plate are wound on both sides via separators having different friction coefficients. It is a group, and the surface of the separator having a large friction coefficient is wound so as to be in contact with the larger one of the positive electrode plate and the negative electrode plate, thereby increasing the adhesion between the separator and the electrode plate. For high-reliability batteries, it is possible to suppress internal short-circuits by suppressing the electrode plate exposure due to the deviation of the separator that occurs at the beginning of winding and the dropping of the mixture layer when forming into a flat shape. An electrode group can be provided.

  In the second invention of the present invention, an electrode group using separators having different friction coefficients on both sides is obtained by using a polyolefin microporous membrane having a heat-resistant porous layer made of aramid on one side. Therefore, it is possible to provide a highly reliable battery electrode group.

  In the third invention of the present invention, the surface of the separator having a large coefficient of friction is wound so as to be in contact with the positive electrode plate, thereby improving the adhesion between the positive electrode plate and the separator, so that at the time of lamination or winding. The exposure of the electrode plate due to the deviation of the separator that occurs at the beginning of winding can be suppressed, and the positive electrode plate having a high energy density is always covered with the separator, thereby providing a battery electrode group with higher safety. .

  In the fourth invention of the present invention, the surface of the separator having a large friction coefficient is wound so as to be in contact with the negative electrode plate. Suppressing the dropping of the negative electrode mixture layer, the negative electrode mixture layer is surely opposed to the opposing positive electrode mixture layer, thereby suppressing an internal short circuit due to lithium deposition, and a higher safety battery electrode. Groups can be provided.

In the fifth invention of the present invention, any one of the first to fourth batteries of the present invention is used as a battery electrode group and enclosed in a battery case together with a non-aqueous electrolyte, thereby causing a separator displacement. Exposure of the electrode plate can be suppressed, and internal short circuit caused by these can be effectively suppressed. In addition, the lithium intercalated with the negative electrode plate can suppress the stress applied to the electrode group when the volume increases due to the expansion of the negative electrode plate, thereby suppressing the buckling of the electrode plate and breaking the electrode plate It is possible to suppress the internal short circuit due to the mixture dropping, breaking or buckling of the electrode plate, and to provide a highly safe battery.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.
(Embodiment 1)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A prismatic non-aqueous secondary battery 1 which is an example of the battery shown in FIG. 1 of the present invention has a battery electrode group 2 housed inside a bottomed flat battery case 3 together with an insulating plate 4, and the battery electrode group 2 The negative electrode lead 5 led out from the upper part of the battery is connected to a terminal 7 having an insulating gasket 6 attached to the periphery, and then the positive electrode lead 8 led out from the upper part of the battery electrode group 2 is connected to the sealing plate 9. The sealing plate 9 is inserted into the opening, the sealing plate 9 and the battery case 3 are welded and sealed along the outer periphery of the opening of the battery case 3, and a predetermined amount of nonaqueous solvent is supplied from the plug opening 10 to the battery case 3. After injecting a non-aqueous electrolyte solution (not shown) consisting of the following, the sealing plug 11 is welded to the sealing plate 9.

  Here, as shown in FIG. 2, the battery electrode group 2 has a porous insulation between a positive electrode plate 12 using a composite lithium oxide as an active material and a negative electrode plate 13 using a material capable of holding lithium as an active material. It is configured to be wound in a spiral through a separator 14 as a layer. Here, the friction coefficients of the surfaces of the positive electrode plate 12 and the negative electrode plate 13 are different. More specifically, as shown in FIG. 3, the positive electrode plate 12, the separator 14, the negative electrode plate 13, and the separator 14 are arranged, wound around a winding core (not shown) in the direction indicated by A, and wound in a spiral shape. Can be configured. Thereafter, in the case of a flat battery, it is formed into a flat shape by a process as shown in FIG. The separator 14 has a configuration in which the friction coefficient is different between the front and back sides, a heat-resistant porous layer 15a made of aramid is formed on one side, and one side is made by using the separator 14 made of a microporous film layer 15b. A heat-resistant porous layer 15a having a large friction coefficient of the separator 14 is disposed on the surface facing the positive electrode plate 12, and is wound around a winding core (not shown) in the direction indicated by A together with the negative electrode plate 13 and the separator 14 in a spiral shape. It is structured by winding it around. The thickness of the separator 14 is preferably 10 to 25 μm. By winding the positive electrode plate 12 so that the surface having a large friction coefficient of the separator 14 is in contact with the positive electrode plate 12, exposure due to deviation between the separator and the positive electrode plate 12 during winding can be suppressed, and when forming into a flat shape By suppressing the dropping of the mixture layer, it is possible to suppress an internal short circuit and to provide a highly reliable battery electrode group 2.

  More specifically, at the start of winding, the positive electrode plate 12, the negative electrode plate 13, and the separator 14 are in a positional relationship as shown in FIG. 5, and the positive electrode plate 12 not sandwiched between the separators 14 is inserted into the core 20. However, if the adhesion is low, it will slip at the time of winding, and it will not be able to wind while maintaining the correct positional relationship. However, as shown in FIG. 3, the surface has a large coefficient of friction. By arranging and winding the surface of the positive electrode plate 12 and the heat-resistant porous layer 15a having a large friction coefficient on the surface facing the positive electrode plate 12, the adhesion between the positive electrode plate 12 and the separator 14 is improved. Adhesion is improved, and the electrode plate can be wound without slipping when the electrode plate enters, particularly at the beginning of winding. Therefore, the exposure of the electrode plate can be suppressed without shifting.

Further, when forming into a flat shape after winding, as shown in FIG. 6 (a), a substantially circular wound body is compressed from above and below, but the winding start portion of the innermost circumference is fixed. Therefore, conventionally, slipping occurs due to deformation due to compression, and it moves inward. For this reason, as shown in FIG. 6B, the separator does not adhere to the electrode plate in the curved portion, and the inner mixture cannot be held during the pressure deformation and falls off. On the other hand, in the embodiment of the present invention, as shown in FIG. 6C, the positive electrode plate 12 and the separator 14 having a large friction coefficient are in close contact with each other. As a result, since the mixture layer can be held even when the curved portion is formed, the mixture layer can be prevented from falling off.

  In the positive electrode plate 12, a positive electrode active material and a binder are put in an appropriate dispersion medium, mixed and dispersed by a disperser such as a planetary mixer, and an optimum viscosity for application to the positive electrode current collector 16 such as an aluminum foil. The positive electrode mixture paint is prepared by kneading while adjusting.

  Here, as the positive electrode active material, for example, lithium cobaltate and modified products thereof (such as lithium cobaltate in which aluminum or magnesium is dissolved), lithium nickelate and modified products thereof (partially nickel is substituted with cobalt) Composite oxides such as lithium manganate and modified products thereof.

  As the conductive material type at this time, for example, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black and thermal black, and various graphites may be used alone or in combination.

  As the binder for the positive electrode at this time, for example, polyvinylidene fluoride (PVdF), a modified polyvinylidene fluoride, polytetrafluoroethylene (PTFE), a rubber particle binder having an acrylate unit, and the like can be used. At this time, an acrylate monomer or an acrylate oligomer into which a reactive functional group is introduced can be mixed in the binder.

  Next, the positive electrode mixture coating material described above is applied to the positive electrode current collector 16 in a predetermined thickness to form the positive electrode mixture layers 17a and 17b, and after drying, the entire surface is pressed to a predetermined thickness. A positive electrode plate 12 is produced.

On the other hand, for the negative electrode plate 13, a negative electrode active material, a conductive material, and a binder are placed in an appropriate dispersion medium, mixed and dispersed by a dispersing machine such as a planetary mixer, and applied to a negative electrode current collector 18 such as a copper foil. The negative electrode mixture paint is prepared by kneading while adjusting the viscosity to the optimum value.
Here, as the negative electrode active material, various natural graphites and artificial graphites, silicon-based composite materials such as silicide, and various alloy composition materials can be used.

  As the binder for the negative electrode at this time, polyvinylidene fluoride and a modified product thereof can be used. However, from the viewpoint of improving the acceptability of lithium ions, styrene-butadiene copolymer rubber particles (SBR) or a modified product thereof and a cellulose resin such as carboxymethyl cellulose (CMC) are used in combination. It is preferable to use a styrene-butadiene copolymer rubber particle or a modified product thereof added with a small amount of the above cellulose resin.

  Next, the negative electrode mixture coating material described above is applied to the negative electrode current collector 18 to a predetermined thickness to form the negative electrode mixture layers 19a and 19b, dried, and then pressed almost entirely to a predetermined thickness. A negative electrode plate 13 is produced.

The non-aqueous electrolyte can use various lithium compounds such as LiPF ₆ and LiBF ₄ as electrolyte salts. Further, ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (MEC) can be used alone or in combination as a solvent. In addition, in order to form a good film on the positive electrode plate 12 or the negative electrode plate 13 and to ensure stability during overcharge, vinylene carbonate (VC), cyclohexylbenzene (CHB), and modified products thereof are used. Is preferred.

(Embodiment 2)
FIG. 7 is a schematic perspective view showing the positive electrode plate 12, the negative electrode plate 13, and the separator 14 according to the second embodiment of the present invention. The description of the same configuration as that in Embodiment 1 is omitted.

  As shown in FIG. 7, a negative electrode plate 13 having a porous insulating layer 21 formed on both sides and a heat-resistant porous layer 15a made of aramid on one side and a separator 14 made of a microporous film layer 15b on one side were used. The heat-resistant porous layer 15a having a large friction coefficient of the separator 14 is disposed on the negative electrode plate 13 and the surface facing the negative electrode plate 13, and is wound in a spiral shape in the direction indicated by A together with the positive electrode plate 12 and the separator 14. Yes.

  More specifically, at the start of winding, the positive electrode plate 12, the negative electrode plate 13, and the separator 14 are in a positional relationship as shown in FIG. 8, and the negative electrode plate 13 not sandwiched between the separators 14 is inserted into the core 20. Although it is necessary to wind up, if the adhesiveness is low, it slips at the time of winding, and it is impossible to wind while maintaining the correct positional relationship. However, as shown in FIG. By arranging and winding the surface of the heat-resistant porous layer 15a having a large friction coefficient of the separator 14 on the surface, the adhesion between the negative electrode plate 13 and the separator 14 is improved, so that the adhesion between the electrode plate and the electrode plate is improved. Since it can wind in without slipping at the time of the entrance of the electrode plate at the beginning, exposure of an electrode plate can be suppressed without slipping.

  Further, when forming into a flat shape after winding, as shown in FIG. 9A, a substantially circular wound body is compressed from above and below, but the winding start portion of the innermost circumference is fixed. Therefore, conventionally, slipping occurs due to deformation due to compression, and it moves inward. For this reason, as shown in FIG. 9B, the separator does not adhere to the electrode plate in the curved portion, and the inner mixture cannot be held during the pressure deformation and falls off. On the other hand, in the embodiment of the present invention, as shown in FIG. 9C, the negative electrode plate 13 and the separator 14 having a large coefficient of friction are in close contact with each other. As a result, since the mixture layer can be retained even when the curved portion is formed, the mixture layer can be prevented from falling off.

  Thereby, it becomes possible to suppress an internal short circuit by suppressing dropping of the mixture layer when forming into a flat shape, and it is possible to provide the battery electrode group 2 with high reliability.

  As described above, since the secondary battery 1 of the present invention has high adhesion between the electrode plate and the separator 14, the expansion of the negative electrode plate 13 due to lithium ions intercalated with the negative electrode plate 13 during charging is suppressed. Therefore, the buckling of the electrode group 2 due to the volume expansion of the electrode plate can be suppressed, and the breakage of the electrode plate and the internal short circuit due to the buckling can be suppressed, and the highly safe secondary battery 1 can be provided.

  In addition, the separator 14 of this Embodiment has the structure from which a friction coefficient differs in the front and back, uses the separator 14 which forms the heat resistant porous layer 15a which consists of an aramid on one side, and consists of the microporous film layer 15b on one side. However, if the composition can withstand the usage range of the secondary battery 1, as shown in FIG. 10, a microporous film of a polyolefin-based resin such as polyethylene or polypropylene, They may be used singly or in combination.

Hereinafter, specific examples will be described in more detail.
Example 1
A positive electrode plate 12, a negative electrode plate 13, and a separator 14 having the same structure as shown in FIG. 3 were produced as follows. First, in the positive electrode plate 12, 100 parts by weight of lithium cobaltate as an active material, 2 parts by weight of acetylene black as a conductive material with respect to 100 parts by weight of the active material, and polyvinylidene fluoride (PVdF) as an active material are used as the active material. A positive electrode mixture paint was prepared by stirring and kneading 2 parts by weight with 100 parts by weight in a double-arm kneader together with an appropriate amount of N-methyl-2-pyrrolidone.

  Next, this positive electrode mixture paint is applied to the front and back surfaces of a positive electrode current collector 16 made of an aluminum foil having a thickness of 15 μm, and after drying, the positive electrode mixture layers 17a and 17b on one side have a thickness of 100 μm respectively. Was made.

  Further, this positive electrode plate 12 is pressed so that the positive electrode mixture layers 17a and 17b on one side have a thickness of 75 μm and a total thickness of 165 μm, respectively, and then slitted to a width optimal for the rectangular non-aqueous secondary battery 1. Thus, a positive electrode plate 12 was produced.

  On the other hand, in the negative electrode plate 13, 100 parts by weight of artificial graphite as an active material and 2.5 parts of a styrene-butadiene copolymer rubber particle dispersion (solid content of 40% by weight) as a binder are 2.5 parts per 100 parts by weight of the active material. 1 part by weight (1 part by weight in terms of solid content of the binder), 1 part by weight of carboxymethylcellulose as a thickener with respect to 100 parts by weight of the active material, and an appropriate amount of water are stirred in a double-arm kneader. A negative electrode mixture paint was prepared.

  Next, this negative electrode mixture paint is applied to the front and back surfaces of a negative electrode current collector 18 made of a copper foil having a thickness of 10 μm, and after drying, the negative electrode mixture layers 19a and 19b on one side have a thickness of 110 μm respectively. Was made.

  Further, this negative electrode plate 13 was pressed so that the negative electrode mixture layers 19a and 19b on one side had a thickness of 85 μm and a total thickness of 180 μm, respectively, and then slitted to a width optimal for the rectangular non-aqueous secondary battery 1. Thus, a negative electrode plate 13 was produced.

  In the separator 14, a porous film whose main component is polyolefin was used as a base material, and a heat-resistant porous layer 15 a made of aramid and having a large friction coefficient was applied to a thickness of 2 μm on one surface.

Using the positive electrode plate 12, the negative electrode plate 13, and the separator 14 produced as described above, a rectangular non-aqueous secondary battery 1 as shown in FIG. 1 was produced. More specifically, as shown in FIG. 3, the heat-resistant porous layer 15a of the positive electrode plate 12, the negative electrode plate 13, and the separator 14 is disposed so as to face the positive electrode plate 12, and is swirled in the direction A in FIG. 100 battery electrode groups 2 wound into a shape and formed flat were produced. 60 batteries are extracted from the battery electrode group 2 and housed together with the insulating plate 4 in the flat bottomed battery case 3, and the negative electrode lead 5 led out from the upper part of the battery electrode group 2 is connected to the peripheral edge of the insulating gasket 6. The positive electrode lead 8 led out from the upper part of the battery electrode group 2 is connected to the sealing plate 9, and the sealing plate 9 is inserted into the opening of the battery case 3 to open the opening of the battery case 3. The battery case 3 and the sealing plate 9 are welded and sealed along the outer periphery of the battery, and a nonaqueous electrolyte solution (not shown) made of a predetermined amount of nonaqueous solvent is injected into the battery case 3 from the plug opening 10. Thereafter, a rectangular non-aqueous secondary battery 1 produced by welding the sealing plug 11 to the sealing plate 9 was taken as Example 1.
(Example 2)
A positive electrode plate 12, a negative electrode plate 13, and a separator 14 having the same structure as shown in FIG. 7 were produced as follows. First, a positive electrode plate 12 and a separator 14 were prepared in the same manner as in Example 1. The negative electrode plate 13 was prepared in the same manner as in Example 1, and then an inorganic compound containing Al 3 O 2 as a filler was applied to the surface thereof with a thickness of 2 μm. A square non-aqueous secondary battery 1 as shown in FIG. 1 was produced using the positive electrode plate 12, the negative electrode plate 13, and the separator 14.

More specifically, as shown in FIG. 7, the heat-resistant porous layer 15a having a large friction coefficient of the positive electrode plate 12, the negative electrode plate 13, and the separator 14 is disposed so as to face the negative electrode plate 13 having a large friction coefficient. Thus, 100 battery electrode groups 2 that were spirally wound in the direction A in FIG. A rectangular nonaqueous secondary battery 1 produced in the same manner as in Example 1 was selected as Example 2 by extracting 60 pieces from these battery electrode groups 2.
(Comparative Example 1)
As the positive electrode plate 12, the negative electrode plate 13, and the separator 14, those produced in the same manner as in Example 1 were used. The battery electrode group 2 is arranged so that the separator 14 having a lower friction coefficient is opposed to the positive electrode plate 12 having a higher friction coefficient, and 100 battery electrode groups 2 formed into a flat shape by winding in a spiral shape are produced. did. A rectangular non-aqueous secondary battery 1 produced in the same manner as in Example 1 was selected as Comparative Example 1 by extracting 60 pieces from these battery electrode groups 2.
(Comparative Example 2)
The positive electrode plate 12 and the negative electrode plate 13 were produced in the same manner as in Example 1. The separator 14 is made of a single polyethylene material, and the friction coefficient between the front and back sides is the same. Using these positive electrode plate 12, negative electrode plate 13, and separator 14, 100 battery electrode groups 2 wound in a spiral shape and formed flat were produced. A rectangular non-aqueous secondary battery 1 produced in the same manner as in Example 1 was selected as Comparative Example 2 by extracting 60 pieces from these battery electrode groups 2.
(Comparative Example 3)
The positive electrode plate 12 and the negative electrode plate 13 were produced in the same manner as in Example 1. The separator 14 was prepared by applying a heat-resistant porous layer 15a made of aramid having a large friction coefficient to a thickness of 2 μm on both surfaces of a porous film as a base material.

  The battery electrode group 2 was placed so that the separator 14 having a lower friction coefficient was opposed to the positive electrode plate 12, and 100 battery electrode groups 2 that were spirally wound and formed flat were produced. A rectangular non-aqueous secondary battery 1 produced in the same manner as in Example 1 was selected as Comparative Example 3 by extracting 60 pieces from these battery electrode groups 2.

  The required contents of each of the above examples and comparative examples are shown in (Table 1).

  In the electrode group 2 and the square nonaqueous secondary battery 1 wound in a spiral shape under the conditions of (Table 1), evaluation was performed with the following contents. Tables 2 and 4 show the results obtained by extracting 40 pieces from 100 pieces for each of Examples 1 and 2 and Comparative Examples 1 to 3 and disassembling and observing the battery electrode group 2.

  Moreover, about 60 square non-aqueous secondary batteries 1 produced about Examples 1-2 and Comparative Examples 1-3 as mentioned above, respectively, the capacity maintenance rate with respect to an initial capacity when charging / discharging is repeated 500 cycles, and The change rate of the thickness of the electrode plate is shown in (Table 2).

Furthermore, the results of disassembling and observing the prismatic non-aqueous secondary battery 1 and the battery electrode group 2 after repeating 30 of these 60 for 500 cycles are shown in (Table 2).

  From the results of (Table 2), in Examples 1 and 2, in both the positive electrode plate 12 and the negative electrode plate 13, defects such as breakage of the electrode plate and dropping of the mixture layer were not recognized. Moreover, as a result of the capacity maintenance ratio with respect to the initial capacity after 500 cycles and the decomposition and observation after 500 cycles, problems such as lithium deposition, electrode plate breakage, electrode plate buckling, and mixture layer falling off were not observed.

  Further, the increase in thickness after 500 cycles is small and buckling is suppressed, and it is considered that good battery characteristics can be maintained.

  On the other hand, in Comparative Examples 1 to 3, the capacity retention ratio with respect to the initial capacity after 500 cycles is reduced, and from the results of decomposition and observation after 500 cycles, lithium deposition, electrode plate breakage, electrode plate buckling, and mixture Problems such as falling off of the layer were observed.

  In addition, the following tests were performed on the remaining 30 after repeating these 500 cycles.

  First, as a drop test, the above-described rectangular non-aqueous secondary battery 1 was charged for 2 hours under the conditions of an upper limit voltage of 4.2 V and a current of 2 A, and then the rectangular non-aqueous secondary battery 1 was placed on a concrete surface from a height of 1.5 m. A drop test was performed 10 times on each of the six surfaces of the secondary battery 1, ten exothermic temperatures were measured at room temperature of 25 ° C., and the average value of the ten cells was obtained (Table 3). Moreover, the result of having confirmed the presence or absence of the heat | fever after a drop test is shown in (Table 3).

  Further, as a round bar crushing test, the above-described rectangular non-aqueous secondary battery 1 was charged for 2 hours under the conditions of an upper limit voltage of 4.2 V and a current of 2 A, and then the battery was laid in a direction perpendicular to the length direction. A crush test was performed with a round bar having a diameter of 10 mm, 10 exothermic temperatures were measured at a room temperature of 25 ° C., and the average value of 10 pieces was obtained (Table 3).

  Furthermore, as a 150 ° C. heating test, the above-described rectangular non-aqueous secondary battery 1 was charged for 2 hours under the conditions of an upper limit voltage of 4.2 V and a current of 2 A, and then the battery was inserted into a constant temperature layer to be 5 ° C./min from normal temperature. Table 3 shows the results obtained by raising the temperature of the constant temperature layer to 150 ° C. under the conditions, measuring the battery heat generation temperature at that time, and obtaining the average value of 10 pieces.

  From the result of (Table 3), in Examples 1-2, the malfunction was not recognized about the drop test after 500 cycles, a round bar crushing test, and a 150 degreeC heating test.

  This is because buckling is suppressed and internal short circuit caused by them can be suppressed, and it is considered that good safety can be maintained.

  On the other hand, the nonaqueous secondary battery 1 shown in Comparative Examples 1 to 3 was decomposed and observed after 500 cycles. As a result, problems such as lithium deposition, electrode plate breakage, electrode plate buckling, and mixture layer falling off were observed. Admitted.

  Also, in any of the drop test, the round bar crush test, the nail penetration test, and the 150 ° C. heating test, the internal temperature caused by the dropping of the mixture layer or the breakage of the electrode plate due to the high exothermic temperature. The cause is considered to be a short circuit or buckling.

  From the above results, the surface of the separator 14 having a different friction coefficient on both sides is configured to be in contact with the larger one of the surface friction coefficient of the positive electrode plate 12 and the negative electrode plate 13. Adhesion is improved, especially by rolling without slipping when the electrode plate enters at the beginning of winding, suppressing exposure of the electrode plate without slipping, or suppressing dropping of the mixture layer when deforming flat The internal short circuit accompanying it could be suppressed.

  In Examples 1 and 2, the battery electrode group 2 wound in a spiral shape was created, but it goes without saying that the same effect can be obtained in the battery electrode group 2 stacked in a zigzag manner.

  Furthermore, in these examples, the rectangular non-aqueous secondary battery 1 has been described, but it goes without saying that the same effect can be obtained with a cylindrical non-aqueous secondary battery.

The battery electrode group according to the present invention is a battery electrode group in which a positive electrode plate and a negative electrode plate are wound through separators having different friction coefficients on both surfaces. By making contact with the one with the larger friction coefficient on the surface, the exposure of the electrode plate due to the displacement of the electrode plate at the time of winding is suppressed, and the dropping of the mixture when forming into a flat shape is suppressed It is possible to suppress an internal short circuit. In addition, by using this battery electrode group, it is possible to provide a highly safe battery by suppressing heat generation due to an internal short circuit, and therefore it is desired to increase the capacity with the multi-functionalization of electronic devices and communication devices. It is useful as a portable power source.

DESCRIPTION OF SYMBOLS 1 Square non-aqueous secondary battery 2 Battery electrode group 3 Battery case 4 Insulating plate 5 Negative electrode lead 6 Insulating gasket 7 Terminal 8 Positive electrode lead 9 Sealing plate 10 Sealing port 11 Sealing 12 Positive electrode plate 13 Negative electrode plate 14 Separator 15a Heat resistance Porous layer 15b Microporous film layer 16 Positive electrode current collector 17a, 17b Positive electrode mixture layer 18 Negative electrode current collector 19a, 19b Negative electrode mixture layer 20 Winding core

Claims (5)

  A battery electrode group comprising a positive electrode plate and a negative electrode plate having different friction coefficients on the surface, and the positive electrode plate and the negative electrode plate are wound on both sides via separators having different friction coefficients. A battery electrode group comprising: a positive electrode plate and a negative electrode plate wound so as to be in contact with the surface having a larger coefficient of friction.   2. The battery electrode group according to claim 1, wherein a separator having a heat-resistant porous layer made of aramid formed on one surface of a polyolefin microporous membrane is used.   The battery electrode group according to claim 1, wherein the separator is wound so that a surface having a large friction coefficient is in contact with the positive electrode plate.   The battery electrode group according to claim 1, wherein a porous insulating layer is formed on the surface as the negative electrode plate, and the negative electrode plate is wound so that the surface having a large friction coefficient of the separator is in contact with the negative electrode plate. The battery according to any one of claims 1 to 4, wherein an electrode group formed by winding a positive electrode plate and a negative electrode plate through a separator is enclosed in a battery outer package together with an electrolytic solution. A battery characterized by using an electrode group.