JP2010108679A - Electrode group for nonaqueous secondary battery and nonaqueous secondary battery using the same - Google Patents

Abstract

An electrode group is formed by forming a gap between at least one of a positive electrode plate and a porous insulator or between a negative electrode plate and a porous insulator so that the negative electrode expands during charging. The present invention provides a highly safe non-aqueous secondary battery that suppresses buckling and suppresses heat generation due to an internal short circuit caused by buckling of an electrode plate by using this electrode group.
A spacer made of a resin that dissolves in a nonaqueous electrolytic solution to form a void in at least one of a space between a positive electrode plate and a porous insulator or between a negative electrode plate and a porous insulator. The electrode group 4 for non-aqueous secondary batteries was configured by arranging and winding.
[Selection] Figure 1

Description

  The present invention relates to a non-aqueous secondary battery electrode group represented by a lithium ion battery and a non-aqueous secondary 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 a transition metal such as LiCoO ₂ and lithium 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, the electrode group in which the above-described positive electrode plate and negative electrode plate are spirally wound through a separator is housed in a battery case made of a metal such as stainless steel, nickel-plated iron, or aluminum, and then After injecting the 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.

  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. Therefore, it is necessary to devise safety measures such as lowering 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.

  In addition, when a nonaqueous secondary battery is charged and discharged, stress due to expansion and contraction of the electrode plate is applied to the electrode plate, and the electrode plate buckles due to repeated stress due to repeated charge and discharge, and the shape of the electrode group is deformed accordingly. When the shape of the group is further deformed, the battery case is pushed from the inside by the stress, and the battery case expands. Furthermore, when the deformation of the shape of the electrode group proceeds, the positive electrode plate, the negative electrode plate or the separator having the lowest elongation rate breaks preferentially, and the positive electrode plate or the negative electrode plate breaks before the separator. The broken portion of any of the electrode plates breaks through the separator, and the positive electrode plate and the negative electrode plate are short-circuited. Due to this short circuit, a large current flows, and as a result, the temperature of the non-aqueous secondary battery rises rapidly, and the non-aqueous secondary battery may run out of heat as described above.

Therefore, in order to suppress such buckling, for example, as shown in FIG. 8, the belt 92 stretched between the rotating rollers is rotated in a state where the electrode group 91 is wound and pressed from above to be deformed. Thus, a method has been proposed in which the winding state is loosened by rotating in the same direction as the winding direction or in the opposite direction (see Patent Document 1, for example).

In order to suppress such buckling, for example, as shown in FIG. 9, when the positive electrode plate C, the separator S1, the negative electrode plate A, and the separator S2 are stacked and wound in a spiral shape, the negative electrode plate A method has been proposed in which metal lithium P1 and metal lithium P2 are attached to the front and back surfaces of A to form a gap between the electrodes (see, for example, Patent Document 2).
JP 2006-164958 A JP 2008-016193 A

  However, in the prior art disclosed in Patent Document 1 described above, after being wound, it is pressed and deformed to rotate in the same direction as the winding direction or in the opposite direction to loosen the winding state to form a gap between the electrodes. However, although it is effective in forming the gap, it is difficult to always loosen the electrode group once wound quantitatively. Also, the electrode group is rotated while being pressed and deformed, so that the mixture layer falls off from the electrode plate, and the exposed current collectors come into contact with each other, or the removed mixture layer penetrates the separator. In some cases, this causes a short circuit between the positive electrode plate and the negative electrode plate, which is not sufficient for ensuring the safety of the non-aqueous secondary battery.

  Moreover, in the prior art of patent document 2, metal lithium is arrange | positioned between a separator and a negative electrode plate, and an electrode group is comprised, but there exists lithium more than lithium supplied from a mixture layer because this lithium melts out. It becomes a state of excessive lithium and causes lithium dendrite. When lithium dendrite occurs, it may break through the separator and cause the positive electrode plate and the negative electrode plate to be short-circuited, which is sufficient to ensure the safety of non-aqueous secondary batteries I had a problem that I could not say.

  The present invention repeats charging and discharging by arranging a spacer made of a resin that dissolves in a non-aqueous electrolyte between at least one of a positive electrode plate and a porous insulator or between a negative electrode plate and a porous insulator. For the purpose of providing a highly reliable non-aqueous secondary battery electrode group, the spacer part dissolved in the non-aqueous electrolyte absorbs buckling due to the expansion and contraction of the electrode plate as a void. Yes.

  In order to solve the above-described conventional problems, the electrode group for a non-aqueous secondary battery according to the present invention includes a positive electrode mixture in which an active material composed of at least a lithium-containing composite oxide, a conductive material, and a binder are kneaded and dispersed in a dispersion medium. A negative electrode mixture paint in which a positive electrode plate in which a positive electrode mixture layer is formed by applying a paint on a positive electrode current collector and an active material and a binder made of a material capable of holding at least lithium are kneaded and dispersed in a dispersion medium. An electrode group for a non-aqueous secondary battery in which a negative electrode plate coated on a current collector and having a negative electrode mixture layer formed thereon is spirally wound or spirally stacked via a porous insulator. In addition, a spacer made of a resin that dissolves in the nonaqueous electrolytic solution is disposed between at least one of the positive electrode plate and the porous insulator or between the negative electrode plate and the porous insulator.

According to the electrode group for a non-aqueous secondary battery of the present invention, a spacer made of a resin that dissolves in a non-aqueous electrolyte at least one of between a positive electrode plate and a porous insulator or between a negative electrode plate and a porous insulator. As a result, the spacer is dissolved by the non-aqueous electrolyte to form a void inside the electrode group, and the negative electrode plate is formed by lithium intercalated with the negative electrode plate. The volume increase due to the expansion of the electrode is absorbed by the void formed inside the electrode group, so that the stress applied to the positive electrode plate can be relaxed, the buckling of the electrode plate can be suppressed, and the breakage of the electrode plate can be suppressed. is there. In addition, by using this electrode group, it is possible to provide a highly safe non-aqueous secondary battery by suppressing internal short circuit due to fracture or buckling of the electrode plate.

  In the first invention of the present invention, a positive electrode mixture paint obtained by kneading and dispersing at least an active material composed of a lithium-containing composite oxide, a conductive material, and a binder with a dispersion medium is applied onto a positive electrode current collector. A negative electrode mixture layer obtained by applying a negative electrode mixture coating material obtained by kneading and dispersing an active material and a binder made of a material capable of holding lithium at least in a dispersion medium on a negative electrode current collector. A non-aqueous secondary battery electrode group that is spirally wound or stacked in a zigzag manner via a porous insulator between the positive electrode plate and the porous insulator By placing a spacer made of a resin that dissolves in the non-aqueous electrolyte in at least one of the negative electrode plate and the porous insulator, the spacer forms a void inside the electrode group when it dissolves in the non-aqueous electrolyte. The expansion of the negative electrode plate during charging It is possible to suppress the buckling of the yield said electrode plate, it is possible to provide a highly reliable non-aqueous secondary battery electrode group.

  In the second invention of the present invention, by arranging the spacer on one side of the positive electrode plate or the negative electrode plate, the expansion of the negative electrode plate during charging is absorbed from the beginning of winding to the end of winding. Can be suppressed.

  In the third aspect of the present invention, the spacers are arranged on both surfaces of either the positive electrode plate or the negative electrode plate, thereby absorbing the expansion of the negative electrode plate during charging from the beginning to the end of winding. Thus, buckling of the electrode plate can be more effectively suppressed.

  In the fourth invention of the present invention, the positive electrode plate or the negative electrode plate in which the spacer is spirally wound or stacked in a spiral manner between the long positive electrode plate and the negative electrode plate via a porous insulator. By arranging continuously in the longitudinal direction of the wire, more voids are secured, and the expansion of the negative electrode plate during charging is absorbed from the beginning of winding to the end of winding. Can be suppressed.

  In the fifth invention of the present invention, the positive electrode plate or the negative electrode plate in which the spacer is spirally wound between the long positive electrode plate and the negative electrode plate via a porous insulator or stacked in a zigzag manner. By disposing intermittently with respect to the longitudinal direction, buckling of the electrode plate can be suppressed by more effectively absorbing the influence of expansion at locations where the influence of expansion of the negative electrode plate during charging is large.

  In the sixth aspect of the present invention, since the spacer is made of a polyolefin resin, the polyolefin resin is used as a separator material. The buckling of the electrode plate can be suppressed by forming a gap that can absorb the expansion of the negative electrode plate during charging without deteriorating.

  In the seventh aspect of the present invention, since the spacer is made of a fluorine-based resin, the fluorine-based resin is used as a binder for the electrode plate. The buckling of the electrode plate can be suppressed by forming a gap that can absorb the expansion of the negative electrode plate during charging without deteriorating the battery characteristics.

  In the eighth invention of the present invention, since the spacer is made of fiber reinforced resin, the fibers remain even after the resin is dissolved, so that a void can be secured and buckling can be suppressed, and at the same time, an insulator layer is formed. Heat generation due to an internal short circuit can be suppressed.

  In the ninth aspect of the present invention, the negative electrode plate is expanded during charging by being disposed in the innermost winding of the electrode group in which the spacer is wound in a spiral shape or in the bent portion of the electrode group stacked in a zigzag manner. Of the increase in volume due to the above, it is possible to absorb the deformation of the electrode plate toward the inner peripheral portion and suppress the buckling of the electrode plate.

  In the tenth aspect of the present invention, the spacer is arranged at a location where the curvature radius of the electrode group formed in a flat shape is small, so that the negative electrode plate at the time of charging at a location where the curvature radius is small in the rectangular non-aqueous secondary battery The volume increase accompanying expansion | swelling of can be absorbed more effectively, and the buckling of the electrode plate in a square non-aqueous secondary battery can be suppressed more effectively.

  In an eleventh aspect of the present invention, a positive electrode plate and a negative electrode plate, in which an active material mixture layer containing an active material capable of occluding and releasing lithium ions is formed on a current collector, are spirally formed through a porous insulator. In a non-aqueous secondary battery in which a group of electrodes wound or folded in a zigzag manner is enclosed in a battery case together with a non-aqueous electrolyte, any one of the spacers 1 to 10 of the present invention is dissolved in the non-aqueous electrolyte. By using the electrode group for non-aqueous secondary batteries in which a gap is formed between at least one of the positive electrode plate and the porous insulator or between the negative electrode plate and the porous insulator, the buckling is suppressed. And the internal short circuit resulting from these can be suppressed effectively, and a highly safe non-aqueous secondary battery can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1A, the electrode group 4 for a non-aqueous secondary battery of the present invention includes a positive electrode plate 14 using a composite lithium oxide as an active material and a negative electrode plate 24 using a material capable of holding lithium as an active material. Are wound in a spiral shape through a separator 31 as a porous insulating layer.

  More specifically, as shown in the enlarged view of the main part of the electrode group 4 in FIG. 1B, it is dissolved in the non-aqueous electrolyte between the positive electrode plate 14 and the separator 31 and between the negative electrode plate 24 and the separator 31. A spacer 10 made of resin is placed and wound in a spiral shape. When the electrode group 4 is enclosed in the battery case 36 together with the non-aqueous electrolyte, the spacer 10 is dissolved in the non-aqueous electrolyte, so that a gap can be formed in the electrode group 4. In order to arrange the spacer 10, the spacer 10 is arranged between the positive electrode plate 14 and the separator 31 and between the negative electrode plate 24 and the separator 31 as shown in FIG. It can be constituted by winding in a spiral.

  In the positive electrode plate 14, a positive electrode active material and a binder are placed in an appropriate dispersion medium, mixed and dispersed by a dispersing machine such as a planetary mixer, and the viscosity optimum for application to the positive electrode current collector 11 such as an aluminum foil is obtained. 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 a kind of the conductive material 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 paint described above is applied to the positive electrode current collector 11 to a predetermined thickness to form the positive electrode mixture layers 12a and 12b, dried, and then pressed almost entirely to a predetermined thickness. The positive electrode plate 14 can be produced.

  On the other hand, in the negative electrode plate 24, a negative electrode active material, a conductive material, and a binder are put in an appropriate dispersion medium, mixed and dispersed by a dispersing machine such as a planetary mixer, and applied to the negative electrode current collector 21 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 paint described above is applied to the negative electrode current collector 21 in a predetermined thickness to form the negative electrode mixture layers 22a and 22b, dried, and then pressed almost entirely to a predetermined thickness. The negative electrode plate 24 can be produced.

  In addition, another nonaqueous secondary battery electrode group 4 of the present invention is the one in which the spacer 10 made of a resin dissolved in a nonaqueous electrolytic solution is continuously arranged on the inner peripheral side of the negative electrode plate 24 in the longitudinal direction. As shown in FIG. 2, the spacer 10 is disposed between the negative electrode mixture layer 22a on one side of the negative electrode plate 24 and the separator 31 facing the negative electrode layer 24, and is wound in a spiral shape in the direction indicated by A. .

  Thus, in order to arrange the spacer 10 between the negative electrode mixture layer 22 a and the separator 31, the resin dissolved in the non-aqueous electrolyte cut to the optimum length is continuously separated in the longitudinal direction of the negative electrode plate 24. Affixed on 31 and fixed together with the positive electrode plate 14 and the separator 31. Thus, a gap between the electrode plates can be secured over the entire surface from the start of winding to the end of winding, and the negative electrode plate is absorbed by absorbing the expansion of the negative electrode plate 24 during charging from the entire start to end of winding. The buckling of the electrode plate due to the increase in volume due to the expansion of 24 can be suppressed.

  In addition, another nonaqueous secondary battery electrode group 4 of the present invention is the one in which the spacer 10 made of a resin dissolved in a nonaqueous electrolytic solution is continuously arranged on the inner peripheral side of the negative electrode plate 24 in the longitudinal direction. As shown in FIG. 6, the spacer 10 is disposed between the negative electrode mixture layers 22a and 22b on both sides of the negative electrode plate 24 and the separators 31a and 31b facing each other, and is wound in a spiral shape in the direction indicated by A. Is configured.

  Thus, in order to arrange the spacer 10 between the negative electrode mixture layers 22 a and 22 b and the separator 31, a resin dissolved in the non-aqueous electrolyte cut to an optimum length is continuously provided in the longitudinal direction of the negative electrode plate 24. Affixed to the separator 31 and fixed, and together with the positive electrode plate 14 and the separator 31, a spiral shape is formed. Thus, a gap between the electrode plates can be secured over the entire surface from the start of winding to the end of winding, and the negative electrode plate is absorbed by absorbing the expansion of the negative electrode plate 24 during charging from the entire start to end of winding. The buckling of the electrode plate due to the increase in volume due to the expansion of 24 can be suppressed.

Another electrode group 4 for a non-aqueous secondary battery according to the present invention has spacers 10 made of a resin dissolved in a non-aqueous electrolyte disposed on the inner peripheral side of the negative electrode plate 24 and in the longitudinal direction. As shown, the spacer 10 is intermittently disposed between the negative electrode mixture layer 22a on one side of the negative electrode plate 24 and the separator 31 facing the negative electrode mixture layer 24, and is wound in a spiral shape in the direction indicated by A. . As described above, in order to intermittently arrange the spacer 10 between the negative electrode plate 24 and the separator 31, a resin dissolved in a plurality of non-aqueous electrolytes cut to an optimum length is used with respect to the longitudinal direction of the negative electrode plate 24. Then, it is affixed on the separator 31 and fixed in a spiral shape together with the positive electrode plate 14 and the separator 31. Thereby, buckling of the electrode plate can be suppressed by absorbing the influence of the expansion more effectively at the location where the influence of the expansion of the negative electrode plate 24 is large at the time of charging with less spacer material disposed on the entire surface.

  Another electrode group 4 for a non-aqueous secondary battery according to the present invention is a spacer 10 made of a resin that dissolves in a non-aqueous electrolyte, and is made of a polyolefin-based resin. As shown in FIG. The spacer 10 is arranged between the negative electrode mixture layer 22a on one side and the separator 31 facing the negative electrode mixture layer 22a, and is wound in a spiral shape in the direction indicated by A. Here, polyolefin resins such as polypropylene (PP) and polyethylene (PE) are used in the separator and absorb the expansion of the negative electrode plate 24 during charging without adversely affecting the battery. By forming a gap that can be buckled, buckling can be suppressed.

  Further, another non-aqueous secondary battery electrode group 4 of the present invention comprises a spacer 10 made of a resin dissolved in a non-aqueous electrolyte solution made of a fluorine-based resin. As shown in FIG. The spacer 10 is arranged between the negative electrode mixture layer 22a on one side and the separator 31 facing the negative electrode mixture layer 22a, and is wound in a spiral shape in the direction indicated by A. Here, since a fluorine-based resin, for example, vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymer (THV) is used as a binder for an electrode plate, it does not adversely affect the battery. By forming a gap that can absorb the expansion of the negative electrode plate 24 during charging, buckling can be suppressed.

  Further, another non-aqueous secondary battery electrode group 4 of the present invention comprises a spacer 10 made of a resin that dissolves in a non-aqueous electrolyte, and is made of a fiber reinforced resin. As shown in FIG. The spacer 10 is arranged between the negative electrode mixture layer 22a on one side and the separator 31 facing the negative electrode mixture layer 22a, and is wound in a spiral shape in the direction indicated by A. The fiber reinforced resin has fibers remaining even after the resin is dissolved, so that a void can be secured and buckling can be suppressed. At the same time, since an insulator layer is formed, heat generation due to an internal short circuit can be suppressed.

  Further, another nonaqueous secondary battery electrode group 4 of the present invention is arranged inside the outermost winding of an electrode group in which a spacer 10 made of a resin dissolved in a nonaqueous electrolytic solution is wound in a spiral shape. As shown in FIG. 4, the spacer 10 is arranged at the winding start position and is wound in a spiral shape in the direction indicated by A. In this way, the spacer 10 made of a resin dissolved in the non-aqueous electrolyte cut to the optimum length is attached and fixed to the winding start position of the separator 31 at the winding start position, and together with the positive electrode plate 14 and the separator 31 It has a spiral shape. By arranging at the beginning of winding, it is possible to absorb the deformation of the electrode plate toward the inside of the winding out of the volume increase due to expansion of the negative electrode plate 24 during charging with less spacer material than the entire surface, and more effectively Buckling of the electrode plate can be suppressed.

  Further, another non-aqueous secondary battery electrode group 4 of the present invention is the one in which the spacer 10 made of a resin dissolved in a non-aqueous electrolyte solution is disposed at a location where the curvature radius of the electrode group formed in a flat shape is small, As shown in FIG. 5A, between the negative electrode mixture layer 22a on the inner peripheral side of the negative electrode plate 24 and the separator 31 facing it, the resin cut into an optimal length is wound in a spiral shape. The spacer 10 is arranged so that the pitch increases toward the outside, and when it is spirally wound in the direction shown in A and shaped so as to be flat, a portion having a small radius of curvature as shown in FIG. The spacer 10 is disposed on the entire surface, and with less spacer material disposed on the entire surface, the volume increase associated with the expansion of the negative electrode plate 24 during charging can be more effectively absorbed, and the seat in the rectangular non-aqueous secondary battery can be absorbed. Can suppress the bending more effectively. .

Hereinafter, the nonaqueous secondary battery 30 of the present invention using the electrode group 4 described above will be described. FIG. 7 shows a cutaway perspective view of a square non-aqueous secondary battery. In the prismatic non-aqueous secondary battery 30 of FIG. 7, a resin that dissolves a positive electrode plate 14 using a composite lithium oxide as an active material and a negative electrode plate 24 using a material capable of holding lithium as an active material in a non-aqueous electrolyte. The electrode group 4 is configured by winding it in a spiral shape through a separator 31 on which a spacer 10 made of is arranged.

  The electrode group 4 is accommodated in the bottomed flat battery case 36 together with the insulating plate 37, the negative electrode lead 33 led out from the upper part of the electrode group 4 is connected to a terminal 40 having an insulating gasket 39 attached to the periphery, and then The positive electrode lead 32 led out from the upper part of the electrode group 4 is connected to the sealing plate 38, the sealing plate 38 is inserted into the opening of the battery case 36, and the sealing plate 38 and the battery case 36 are arranged along the outer periphery of the opening of the battery case 36. After sealing the battery case 36 with a non-aqueous electrolyte solution (not shown) made of a non-aqueous solvent, the plug 42 is welded to the sealing plate 38. A square non-aqueous secondary battery 30 is configured. Here, the gap is formed in the electrode group 4 because the spacer 10 is dissolved by the nonaqueous electrolytic solution.

  Here, the separator 31 may have any composition that can withstand the use range of the rectangular non-aqueous secondary battery. In particular, a microporous film of an olefin resin such as polyethylene or polypropylene may be used singly or in combination. preferable. The thickness of the separator 31 is preferably 10 to 25 μm.

The non-aqueous electrolyte at this time 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. Also, in order to form a good film on the positive electrode plate 14 or the negative electrode plate 24 and to ensure the stability during overcharge, vinylene carbonate (VC) and cyclohexylbenzene (CHB) and their modified products are used. Is preferred.

  Hereinafter, specific examples will be described in more detail. First, in the positive electrode plate 14, 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 the positive electrode current collector 11 made of an aluminum foil having a thickness of 15 μm, and after drying, the positive electrode plate 14 has a positive electrode mixture layer 12a, 12b having a thickness of 100 μm. Was made. Further, the positive electrode plate 14 is pressed so that the positive electrode mixture layers 12a and 12b on one side have a thickness of 75 μm and a total thickness of 165 μm, respectively, and then slitted to a specified width of the rectangular non-aqueous secondary battery. The positive electrode plate 14 was produced by processing.

  On the other hand, in the negative electrode plate 24, 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 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 21 made of a copper foil having a thickness of 10 μm, and after drying, the negative electrode mixture layer 22a, 22b on one side has a thickness of 110 μm. Was made. Further, the negative electrode plate 24 is pressed so that the negative electrode mixture layers 22a and 22b on one side have a thickness of 85 μm and a total thickness of 180 μm, respectively, and then slitted to a specified width of the rectangular non-aqueous secondary battery. The negative electrode plate 24 was produced by processing. The spacer 10 was prepared by cutting a vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymer (THV) having a thickness of 10 μm into the length of the negative electrode mixture layer 22 a with the width of the negative electrode plate 24.

  A rectangular non-aqueous secondary battery 30 as shown in FIG. 7 was produced using the positive electrode plate 14, the negative electrode plate 24, and the separator 31 provided with the spacer 10. More specifically, as shown in FIG. 2, the positive electrode plate 14, the negative electrode plate 24, the separator 31 of a polyethylene microporous film having a thickness of 20 μm, and the surface of the separator 31 facing the negative electrode mixture layer 22 a of the negative electrode plate 24. Then, spacers 10 were attached so as to overlap the negative electrode mixture layer 22a, and these were wound spirally in the direction A in FIG.

  60 terminals extracted from the electrode group 4 are accommodated together with an insulating plate 37 in a bottomed flat battery case 36, and a negative electrode lead 33 led out from the upper part of the electrode group 4 is attached to the peripheral edge of an insulating gasket 39. 40, and then the positive electrode lead 32 led out from the upper part of the electrode group 4 is connected to the sealing plate 38. The sealing plate 38 is inserted into the opening of the battery case 36 and sealed along the outer periphery of the opening of the battery case 36. The plate 38 is welded and sealed, and a non-aqueous electrolyte solution (not shown) made of a non-aqueous solvent is injected into the battery case 36 from the plug port 41, and then the plug 42 is connected to the seal plate 38. A rectangular non-aqueous secondary battery 30 produced by welding was taken as Example 1.

  First, the positive electrode plate 14 and the negative electrode plate 24 were produced in the same manner as in Example 1. Next, the spacer 10 was prepared by cutting a vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymer (THV) having a thickness of 5 μm to the length of the negative electrode mixture layer 22 a with the width of the negative electrode plate 24.

  A rectangular non-aqueous secondary battery 30 as shown in FIG. 7 was produced using the positive electrode plate 14, the negative electrode plate 24, and the separator 31 provided with the spacer 10. More specifically, as shown in FIG. 6, the positive electrode plate 14, the negative electrode plate 24, the separator 31 of a polyethylene microporous film having a thickness of 20 μm, and the surface of the separator 31 a facing the negative electrode mixture layer 22 a of the negative electrode plate 24. The spacer 10 is attached so as to overlap the negative electrode mixture layer 22a, and is attached to the surface of the separator 31b facing the negative electrode mixture layer 22b of the negative electrode plate 24 so as to overlap the negative electrode mixture layer 22b. 100 electrode groups 4 that were spirally wound in the direction A in FIG. 6 and formed flat were produced. A rectangular non-aqueous secondary battery 30 produced in the same manner as in Example 1 was extracted from these electrode groups 4 as Example 2.

  First, the positive electrode plate 14 and the negative electrode plate 24 were produced in the same manner as in Example 1. Next, the spacer 10 was prepared by cutting a vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymer (THV) having a thickness of 10 μm into a length of 10 mm along the width of the negative electrode plate 24.

  A rectangular non-aqueous secondary battery 30 as shown in FIG. 7 was produced using the positive electrode plate 14, the negative electrode plate 24, and the separator 31 provided with the spacer 10. More specifically, as shown in FIG. 3, the positive electrode plate 14, the negative electrode plate 24, the separator 31 of a polyethylene microporous film having a thickness of 20 μm, and the surface of the separator 31 facing the negative electrode mixture layer 22 a of the negative electrode plate 24. Then, the spacers 10 were affixed at a pitch of 20 mm so as to overlap with the negative electrode mixture layer 22a, and these were spirally wound in the direction A in FIG. 3 to form 100 electrode groups 4 formed into a flat shape. A rectangular non-aqueous secondary battery 30 produced in the same manner as in Example 1 was extracted from these electrode groups 4 as Example 3.

  First, the positive electrode plate 14 and the negative electrode plate 24 were produced in the same manner as in Example 1. Next, the spacer 10 was prepared by cutting a low density polyethylene (PE) film having a thickness of 10 μm and a molecular weight of 282 into the length of the negative electrode mixture layer 22 a with the width of the negative electrode plate 24.

  A rectangular non-aqueous secondary battery 30 as shown in FIG. 7 was produced using the positive electrode plate 14, the negative electrode plate 24, and the separator 31 provided with the spacer 10. More specifically, as shown in FIG. 2, the positive electrode plate 14, the negative electrode plate 24, the separator 31 of a polyethylene microporous film having a thickness of 20 μm, and the surface of the separator 31 facing the negative electrode mixture layer 22 a of the negative electrode plate 24. Then, spacers 10 were attached so as to overlap the negative electrode mixture layer 22a, and these were wound spirally in the direction A in FIG. A rectangular non-aqueous secondary battery 30 produced in the same manner as in Example 1 was selected as Example 4 by extracting 60 pieces from these electrode groups 4.

  First, the positive electrode plate 14 and the negative electrode plate 24 were produced in the same manner as in Example 1. Next, in the spacer 10, a fiber reinforced resin film having a thickness of 10 μm and an aramid fiber nonwoven fabric impregnated with vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymer (THV) is formed in a negative electrode mixture layer with a width of the negative electrode plate 24. It was cut into a length of 22a.

  A rectangular non-aqueous secondary battery 30 as shown in FIG. 7 was produced using the positive electrode plate 14, the negative electrode plate 24, and the separator 31 provided with the spacer 10. More specifically, as shown in FIG. 2, the positive electrode plate 14, the negative electrode plate 24, the separator 31 of a polyethylene microporous film having a thickness of 20 μm, and the surface of the separator 31 facing the negative electrode mixture layer 22 a of the negative electrode plate 24. Then, spacers 10 were attached so as to overlap the negative electrode mixture layer 22a, and these were wound spirally in the direction A in FIG. A rectangular non-aqueous secondary battery 30 produced in the same manner as in Example 1 was extracted from these electrode groups 4 as Example 5.

  First, the positive electrode plate 14 and the negative electrode plate 24 were produced in the same manner as in Example 1. Next, the spacer 10 was prepared by cutting a vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymer (THV) having a thickness of 10 μm into the length of the negative electrode mixture layer 22 a with the width of the negative electrode plate 24.

  A rectangular non-aqueous secondary battery 30 as shown in FIG. 7 was produced using the positive electrode plate 14, the negative electrode plate 24, and the separator 31 provided with the spacer 10. More specifically, as shown in FIG. 4, the positive electrode plate 14, the negative electrode plate 24, the separator 31 of a polyethylene microporous film having a thickness of 20 μm, and the surface of the separator 31 facing the negative electrode mixture layer 22 a of the negative electrode plate 24. Then, the spacer 10 was attached so as to overlap the winding start portion of the negative electrode mixture layer 22a, and these were spirally wound in the direction A in FIG. 4 to produce 100 electrode groups 4 formed into a flat shape. Sixty six of these electrode groups 4 were extracted, and a rectangular non-aqueous secondary battery 30 produced in the same manner as in Example 1 was designated as Example 6.

  First, the positive electrode plate 14 and the negative electrode plate 24 were produced in the same manner as in Example 1. Next, the spacer 10 was prepared by cutting a vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymer (THV) having a thickness of 10 μm into a length of 10 mm along the width of the negative electrode plate 24.

A rectangular non-aqueous secondary battery 30 as shown in FIG. 7 was produced using the positive electrode plate 14, the negative electrode plate 24, and the separator 31 provided with the spacer 10. More specifically, as shown in FIG. 5A, a positive electrode plate 14, a negative electrode plate 24, a separator 31 of a polyethylene microporous film having a thickness of 20 μm, and a separator 31 facing the negative electrode mixture layer 22a of the negative electrode plate 24. A spacer 10 is attached to the surface of the substrate 10 in such a manner that the pitch P1 is 20 mm, the pitch P2 is 21 mm, and the pitch P3 is 22 mm so as to overlap the negative electrode mixture layer 22a. 100 electrode groups 4 which were wound into a shape and formed into a flat shape were produced. A rectangular non-aqueous secondary battery 30 produced in the same manner as in Example 1 was extracted from these electrode groups 4 as Example 7.

(Comparative Example 1)
The positive electrode plate, the negative electrode plate, and the separator were the same as those used in Example 1, and the positive electrode plate, the negative electrode plate, and a separator provided with no spacers were used, and the electrode group was formed into a flat shape by being spirally wound. 100 4 were produced. A rectangular non-aqueous secondary battery 30 produced in the same manner as in Example 1 was extracted from these electrode groups 4 as Comparative Example 1.

(Comparative Example 2)
First, the same positive electrode plate 14 and negative electrode plate 24 as in Example 1 were produced. Next, in the spacer 10, a high-density polyethylene (PE) film having a thickness of 10 μm and a molecular weight of 28000 which is large and does not dissolve in the non-aqueous electrolyte is cut to the length of the negative electrode mixture layer 22 a with the width of the negative electrode plate 24. Made.

  Using the positive electrode plate 14, the negative electrode plate 24, and the separator 31 provided with the spacer 10, the rectangular non-aqueous secondary battery 30 as shown in FIG. More specifically, as shown in FIG. 2, the positive electrode plate 14, the negative electrode plate 24, the separator 31 of a polyethylene microporous film having a thickness of 20 μm, and the surface of the separator 31 facing the negative electrode mixture layer 22 a of the negative electrode plate 24. The spacer 10 was affixed so as to overlap the negative electrode mixture layer 22a, and these were spirally wound in the direction A of FIG. A rectangular non-aqueous secondary battery 30 produced in the same manner as in Example 1 was extracted from these electrode groups 4 as Comparative Example 2.

  (Table 1) shows the required contents of the spacer thickness, the spacer location, the spacer shape, and the resin material used as the spacer in each of the above examples and comparative examples.

  In the electrode group 4 and the square non-aqueous secondary battery 30 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 of each of Examples 1 to 7 and Comparative Examples 1 and 2 and disassembling the electrode group 4 and observing them.

  Furthermore, with respect to each of the 60 rectangular non-aqueous secondary batteries 30 produced for Examples 1 to 7 and Comparative Examples 1 and 2 as described above, the capacity maintenance ratio with respect to the initial capacity when charging and discharging were repeated 500 cycles, and The result of measuring the distance between the positive electrode current collector at the curved portion in the winding by taking a cross-sectional photograph at the center in the height direction in the initial state and the charged state in the middle of 500 cycles in the thickness change rate Is shown in (Table 2). Further, Table 30 shows the result of disassembling and observing the prismatic nonaqueous secondary battery and the electrode group after repeating 30 of these 60 for 500 cycles.

  From the results of (Table 2), in Examples 1 to 7, in both the positive electrode plate 14 and the negative electrode plate 24, defects such as breakage of the electrode plate and dropping of the electrode mixture layer were not recognized. Moreover, as a result of the capacity retention ratio with respect to the initial capacity after 500 cycles and the decomposition and observation after 500 cycles, no defects such as lithium deposition, electrode plate breakage, electrode plate buckling, and electrode mixture layer falling off were observed. In addition, the increase in thickness after 500 cycles was small and buckling was suppressed, and it was considered that good battery characteristics could be maintained. Further, in the initial state, the distance between the positive electrode current collectors according to the CT photograph is increased by an amount corresponding to the spacer thickness in addition to the integrated thickness of the electrode plate and the separator, but the distance does not change even in the charged state. This is considered to be because the increase in volume due to the expansion of the negative electrode due to charging could be absorbed by the voids secured by dissolution of the spacer.

  On the other hand, in Comparative Examples 1 and 2, the capacity retention rate with respect to the initial capacity after 500 cycles is reduced, and the results of decomposition and observation after 500 cycles are also lithium deposition, electrode plate breakage, electrode plate buckling, Inconveniences such as dropping of the electrode mixture layer were observed. Further, the increase in thickness was large, and it was found from the CT photograph that buckling occurred. Furthermore, the distance between the positive electrode current collectors is larger than that in the initial state, which is considered to be due to the increase in volume due to the expansion of the negative electrode due to charging. Although the comparative example 2 inserted the spacer, since it is not melt | dissolved in a non-aqueous electrolyte because it is a high molecular polyethylene film, it cannot be formed in a space | gap, Therefore It is thought that the volume increase by expansion | swelling of a negative electrode cannot be absorbed.

  Moreover, the following tests were done about the remaining 30 after repeating these 500 cycles. As a drop test, the above-mentioned prismatic non-aqueous secondary battery 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 prismatic non-aqueous secondary battery was placed on the concrete surface from a height of 1.5 m. Table 6 shows the results of performing a drop test 10 times on 6 surfaces of the battery, measuring 10 exothermic temperatures at a room temperature of 25 ° C., and obtaining an average value of 10 cells. Moreover, the result of having confirmed the presence or absence of the heat | fever after a drop test is shown in (Table 3).

  In the round bar crushing test, the above-mentioned rectangular non-aqueous secondary battery 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 diameter was perpendicular to the length direction with the battery lying down. The crushing test was carried out with a 10 mm round bar, 10 exothermic temperatures were measured at room temperature of 25 ° C., and the average value of 10 was determined (Table 3).

  Furthermore, as a 150 ° C. heating test, the above-described rectangular non-aqueous secondary battery 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./minute from room 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 1-7, the malfunction was not recognized also about the drop test after 500 cycles, a round bar crush 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. Further, in Example 5, the aramid fibers are added in the resin to be dissolved. However, even if the resin is dissolved, the aramid fibers remain to form an insulating layer, which is further effective for safety. I found it big.

On the other hand, the nonaqueous secondary battery shown in Comparative Example 1 that was not subjected to any decomposition was observed after 500 cycles. As a result, lithium deposition, electrode plate breakage, electrode plate buckling, electrode mixture layer omission, etc. The defect was recognized. Moreover, in any of the drop test, the round bar crush test, the nail penetration test, and the 150 ° C. heat test, the heat generation temperature is high, and therefore internal short circuit caused by dropping of the mixture layer or winding of the electrode plate during winding The cause is considered to be buckling.

  From the above results, it is possible to suppress buckling due to volume increase due to expansion of the negative electrode during charging and internal short circuit associated therewith by arranging a resin that dissolves in the non-aqueous electrolyte and forms voids. I can say that. In Examples 1 to 7, a gap was formed between the negative electrode plate and the separator. However, the present invention is not limited to this, and only the positive electrode plate or the positive electrode plate and the separator and the negative electrode plate and the separator are formed. Needless to say, the same effect can be obtained.

  Further, in Examples 1 to 7, as described above, a resin that completely dissolves in the non-aqueous electrolyte is used as a spacer in order to form a space in at least one of the positive electrode plate and the separator or the negative electrode plate and the separator. Although the used Example was described, it is not limited to this, It cannot be overemphasized that the same effect is acquired even if a part of resin remains. Moreover, in Examples 1-7, although the electrode group wound by the spiral shape was created, it cannot be overemphasized that the same effect is acquired also in the electrode group laminated | stacked in zigzag form. Further, in these examples, the description has been given using the rectangular non-aqueous secondary battery, but it goes without saying that the same effect can be obtained also for the cylindrical non-aqueous secondary battery.

  The electrode group for a non-aqueous secondary battery according to the present invention has a void formed by dissolving in a non-aqueous electrolyte between at least one of a positive electrode plate and a porous insulator or between the negative electrode plate and the porous insulator. By arranging the spacers made of the resin to be formed to constitute the electrode group, it is possible to absorb the volume increase due to the expansion of the negative electrode during charging, thereby suppressing the buckling of the electrode plate. In addition, by using this electrode group, it is possible to provide a highly safe non-aqueous secondary battery that suppresses heat generation due to internal short-circuiting due to buckling of the electrode plate, so that the multifunction of electronic devices and communication devices This is useful as a portable power source or the like for which a higher capacity is desired as a result of the increase in capacity.

(A) Schematic diagram showing a cross section of a non-aqueous secondary battery electrode group according to an embodiment of the present invention, (b) Partial enlarged view of a non-aqueous secondary battery electrode group according to an embodiment of the present invention. (C) Schematic which shows the positive electrode plate which concerns on one Example of this invention, a negative electrode plate, and a separator with a spacer. Schematic which shows the positive electrode plate which concerns on one Example of this invention, a negative electrode plate, and a separator with a spacer. Schematic which shows the positive electrode plate which concerns on one Example of this invention, a negative electrode plate, and a separator with a spacer. Schematic which shows the positive electrode plate which concerns on one Example of this invention, a negative electrode plate, and a separator with a spacer. (A) Schematic which shows the positive electrode plate and negative electrode plate which concern on one Example of this invention, and a separator with a spacer, (b) The partially expanded view of the electrode group for non-aqueous secondary batteries which concerns on one Example of this invention Schematic which shows the positive electrode plate which concerns on one Example of this invention, a negative electrode plate, and a separator with a spacer. 1 is a partially cutaway perspective view of a rectangular nonaqueous secondary battery according to an embodiment of the present invention. Sectional drawing of the electrode plate for non-aqueous secondary batteries in a conventional example Sectional drawing of the electrode plate for non-aqueous secondary batteries in a conventional example

Explanation of symbols

4 Electrode group for non-aqueous secondary battery 10 Spacer 11 Positive electrode current collector 12a, 12b Positive electrode mixture layer 14 Positive electrode plate 21 Negative electrode current collector 22a, 22b Negative electrode mixture layer 24 Negative electrode plate 30 Square non-aqueous secondary battery 31, 31a, 31b Separator 32 Positive electrode lead 33 Negative electrode lead 36 Battery case 37 Insulating plate 38 Sealing plate 39 Insulating gasket 40 Terminal 41 Sealing port 42 Sealing A A Winding direction of electrode group P, P1, P2, P3 Pitch

Claims (11)

  A positive electrode plate having a positive electrode mixture layer formed by applying a positive electrode mixture paint obtained by kneading and dispersing an active material comprising at least a lithium-containing composite oxide, a conductive material, and a binder in a dispersion medium on a positive electrode current collector; A negative electrode mixture coating material in which an active material made of a material capable of holding lithium and a binder are kneaded and dispersed in a dispersion medium is applied on the negative electrode current collector to form a porous material between the negative electrode plate and the negative electrode plate. A non-aqueous secondary battery electrode group wound in a spiral shape or stacked in a zigzag manner via a porous insulator, between the positive electrode plate and the porous insulator or between the negative electrode plate and the porous insulator An electrode group for a non-aqueous secondary battery, wherein a spacer made of a resin that dissolves in a non-aqueous electrolyte is disposed in at least one of the electrodes.   The electrode group for a non-aqueous secondary battery according to claim 1, wherein the spacer is disposed on one side of the positive electrode plate or the negative electrode plate.   The electrode group for a non-aqueous secondary battery according to claim 1, wherein the spacer is disposed on both surfaces of either the positive electrode plate or the negative electrode plate.   The spacer is spirally wound between the long positive electrode plate and the negative electrode plate via a porous insulator or continuously stacked in the longitudinal direction of the positive electrode plate or the negative electrode plate. The electrode group for a non-aqueous secondary battery according to claim 1, wherein   The spacer is wound between the long positive electrode plate and the negative electrode plate in a spiral manner or in a zigzag manner via a porous insulator, and is intermittent with respect to the longitudinal direction of the positive electrode plate or the negative electrode plate. The electrode group for a non-aqueous secondary battery according to claim 1, wherein   The electrode group for a non-aqueous secondary battery according to claim 1, wherein the spacer is made of a polyolefin resin.   The electrode group for a non-aqueous secondary battery according to claim 1, wherein the spacer is made of a fluorine-based resin.   The electrode group for a non-aqueous secondary battery according to claim 1, wherein the spacer is made of a fiber reinforced resin.   2. The electrode for a non-aqueous secondary battery according to claim 1, wherein the spacer is disposed in the innermost winding of the electrode group wound in the spiral shape or in a bent portion of the electrode group stacked in a zigzag manner. group.   The electrode group for a non-aqueous secondary battery according to claim 1, wherein the spacer is disposed at a location where the curvature radius of the electrode group formed in a flat shape is small.   The positive electrode plate and the negative electrode plate, in which an active material mixture layer containing an active material capable of occluding and releasing lithium ions is formed on a current collector, are spirally wound or stacked in a spiral manner via a porous insulator. In the non-aqueous secondary battery in which an electrode group is sealed in a battery case together with a non-aqueous electrolyte, the spacer described in any one of claims 1 to 10 is dissolved in the non-aqueous electrolyte and the positive electrode plate A non-aqueous secondary battery comprising an electrode group for a non-aqueous secondary battery in which a void is formed between at least one of the electrode and the porous insulator or between the negative electrode plate and the porous insulator.

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