Power storage cell

Abstract

To provide a power storage cell that restrains a crack or the like from being generated in an electrode mixture layer.SOLUTION: A power storage cell includes: an electrode body in which a sheet body is wound so as to surround a winding axis line; and a case in which the electrode body is housed. The sheet body includes an electrode sheet and a separator, and the electrode sheet includes a current collector plate and an electrode mixture layer formed on the current collector plate. The electrode sheet includes a groove portion which extends in a direction of the winding axis line and in which the electrode mixture layer is not formed. A plurality of the groove portions is formed in a direction in which the electrode sheet extends, and an interval between the groove portions on a winding inner side is smaller than an interval between the groove portions on a winding outer side.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to an energy storage cell. [Background technology]

[0002] Patent Document 1 (JP 2001-6749 A) ​​discloses a lithium secondary battery having a wound internal electrode assembly in which a positive electrode metal foil and a negative electrode metal foil are arranged with a separator in between. The internal electrode assembly is formed by winding a positive electrode sheet, a separator, and a negative electrode sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-6749 A Summary of the Invention [Problem to be solved by the invention]

[0004] The electrode assembly of the lithium secondary battery configured as described above is formed by winding each sheet.

[0005] For example, the winding radius is small at the winding center of the electrode body. As a result, the winding radius of the positive electrode mixture layer of the positive electrode sheet is also small at the winding center, and the positive electrode mixture layer peels off or cracks occur in the positive electrode mixture layer. The same problem occurs in the negative electrode mixture layer of the negative electrode sheet.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide an electricity storage cell in which the occurrence of cracks and the like in an electrode mixture layer is suppressed. [Means for solving the problem]

[0007] [1] An electrode body in which a sheet body is wound so as to surround a periphery of a winding axis; A case in which the electrode body is housed; Equipped with The sheet body includes an electrode sheet and a separator, The electrode sheet includes a current collector plate and an electrode mixture layer formed on the current collector plate, the electrode sheet has a groove portion extending in the winding axis direction and in which the electrode mixture layer is not formed, The groove portion is formed in a plurality of portions in a direction in which the electrode sheet extends, A storage cell, wherein the spacing between the grooves on the inner side of the winding is smaller than the spacing between the grooves on the outer side of the winding.

[0008] [2] The electrode body has a starting end of the wound body of the electrode body and a terminal end of the wound body of the electrode body, The storage cell according to [1], wherein the spacing between the grooves increases from the starting end toward the terminal end.

[0009] [3] The energy storage cell according to [1] or [2], wherein a groove width of the groove portion on the inner side of the winding is smaller than a groove width of the groove portion on the outer side of the winding.

[0010] [4] The electrode sheet includes a positive electrode sheet and a negative electrode sheet, The positive electrode sheet includes a positive electrode current collector and a positive electrode mixture layer formed on the positive electrode current collector, the positive electrode sheet has a positive electrode groove portion extending in the winding axis direction and in which the positive electrode mixture layer is not formed, The negative electrode sheet includes a negative electrode current collector and a negative electrode mixture layer formed on the negative electrode current collector, the negative electrode sheet has a negative electrode groove portion extending in the winding axis direction and in which the negative electrode mixture layer is not formed, The storage cell according to any one of [1] to [3], wherein the positive electrode groove portion and the negative electrode groove portion are formed to face each other.

[0011] [5] The storage cell according to [4], wherein the groove width of the negative electrode groove portion is smaller than the groove width of the positive electrode groove portion. Effect of the Invention

[0012] According to the energy storage cell according to the present disclosure, the occurrence of cracks and the like in the electrode mixture layer can be suppressed. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing a storage cell 1 according to the present embodiment. [Diagram 2] FIG. 2 is a perspective view showing a schematic view of an electrode body 10. [Diagram 3] FIG. 2 is a plan view showing a positive electrode sheet 22. [Figure 4] FIG. 2 is a plan view showing a negative electrode sheet 24. [Diagram 5] FIG. 2 is a development view showing a state in which the sheet body 20 is developed and the individual sheets are arranged. [Figure 6] 6 is a cross-sectional view showing the positive electrode sheet 22, the negative electrode sheet 24, the separator 21 and the separator 23 in FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference characters, and the description thereof will not be repeated.

[0015] 1 is a cross-sectional view showing an energy storage cell 1 according to the present embodiment. The energy storage cell 1 includes a cylindrical electrode body 10 formed so as to surround a winding axis O, a case 11, a positive electrode current collecting member 12, a negative electrode current collecting member 13, insulating members 14 and 15, and a positive electrode terminal 16.

[0016] 1 and the like, "Z" indicates the direction in which the winding axis O extends. "Z1" indicates one direction of the Z direction. "Z2" indicates the other direction of the Z direction. "R" indicates the radial direction of the electrode body 10.

[0017] The case 11 includes a top plate 17, a bottom plate 18, and a peripheral wall 19. The case 11 is formed of a metal material. The top plate 17 is located at one end of the case 11, and the bottom plate 18 is located at the other end of the case 11. The peripheral wall 19 is disposed between the top plate 17 and the bottom plate 18.

[0018] A through hole 7 is formed in the top plate 17. The insulating member 14 is disposed on the outer surface of the top plate 17, and a through hole is formed in the insulating member 14.

[0019] The insulating member 15 includes a top plate portion 2 and a peripheral wall 3 provided on the outer periphery of the top plate portion 2. The top plate portion 2 is disposed on the inner surface of a top plate 17. The peripheral wall 3 is disposed on the inner periphery of a peripheral wall 19. The top plate 17 has a through hole formed therein.

[0020] The positive electrode terminal 16 includes a flat plate 50 and a shaft 51. The flat plate 50 is disposed on the insulating member 14. The shaft 51 is connected to the flat plate 50 and is formed so as to extend in the Z2 direction. The shaft 51 is inserted into the case 11 through a through hole 7 formed in the insulating member 14 and a through hole formed in the insulating member 15.

[0021] The positive current collecting member 12 is disposed on the Z2 direction side with respect to the insulating member 15. The positive current collecting member 12 is formed in a plate shape, and the lower end of the shaft 51 is welded to the upper surface of the positive current collecting member 12. The positive current collecting member 12 is formed of, for example, aluminum.

[0022] The negative electrode current collecting member 13 is disposed on the inner surface of the bottom plate 18. The negative electrode current collecting member 13 is formed in a plate shape and is made of a metal material such as copper.

[0023] The electrode body 10 is disposed within the case 11 between a positive electrode current collecting member 12 and a negative electrode current collecting member 13 .

[0024] The electrode body 10 includes a first end 5 located on the Z1 direction side, and a positive electrode current collecting member 12 is disposed at the first end 5. The electrode body 10 includes a second end 6 located on the Z2 direction side, and a negative electrode current collecting member 13 is disposed at the second end 6. The electrode body 10 is formed in a hollow shape, and a hollow portion 43 is formed. The hollow portion 43 is formed at a position passing through the winding axis O.

[0025] 2 is a perspective view that shows a schematic view of the electrode body 10. The electrode body 10 includes a sheet body 20 that is formed so as to surround the periphery of the winding axis O. Note that "D" is the direction in which the sheet body 20 extends in the electrode body 10 in a wound state.

[0026] The sheet body 20 is formed long in the winding direction D of the electrode body 10. The sheet body 20 includes a separator 21, a positive electrode sheet 22, a separator 23, and a negative electrode sheet 24.

[0027] Fig. 3 is a plan view showing the positive electrode sheet 22. The positive electrode sheet 22 shown in Fig. 3 is in a state in which it has been unwound from the electrode body 10 and is unfolded. The positive electrode sheet 22 includes long sides 30, 31 and short sides 32, 33. The long sides 30, 31 extend in the L1 direction in which the positive electrode sheet 22 extends. The L1 direction corresponds to the winding direction D in the wound electrode body 10. The long side 30 is located at the first end 5 of the electrode body 10 in the wound state, and the long side 31 is located at the second end 6 of the electrode body 10 in the wound state.

[0028] Positive electrode sheet 22 includes a positive electrode current collector 25 and a positive electrode mixture layer 26. Positive electrode current collector 25 is formed of a metal material such as aluminum or an aluminum alloy.

[0029] The positive electrode mixture layer 26 includes a positive electrode active material, a binder, etc. The positive electrode active material includes, for example, LiCoO2, LiNo2, LiMn2O4, etc. The thickness of the positive electrode mixture layer 26 is, for example, not less than 0.1 μm and not more than 1000 μm.

[0030] The positive electrode mixture layer 26 may be formed on either the front or back surface of the positive electrode current collector 25, or may be formed on one surface. The positive electrode sheet 22 has a positive electrode groove portion 27 extending in the direction of the winding axis O, where the positive electrode mixture layer 26 is not formed. A plurality of positive electrode groove portions 27 are formed in the direction in which the positive electrode sheet 22 extends. The positive electrode mixture layer 26 is separated by a plurality of positive electrode groove portions 27. When the positive electrode mixture layer 26 is formed on both the front and back surfaces of the positive electrode current collector 25, the positive electrode groove portion 27 may be formed on either of the positive electrode mixture layers 26 on the front and back surfaces, or may be formed on one surface. When the positive electrode groove portion 27 is formed on one surface, the one surface is preferably formed on the side that is the outside of the winding.

[0031] FIG. 4 is a plan view showing the negative electrode sheet 24. The negative electrode sheet 24 shown in FIG. 4 is in a state in which it has been unwound from the electrode body 10 and is unfolded. The negative electrode sheet 24 includes long sides 36, 37 and short sides 38, 39. The long sides 36, 37 extend in the L2 direction in which the negative electrode sheet 24 extends. The L2 direction corresponds to the winding direction D in the wound electrode body 10. The long side 36 is located at the first end 5 of the electrode body 10 in the wound state, and the long side 37 is located at the second end 6 of the electrode body 10 in the wound state.

[0032] The negative electrode sheet 24 includes a negative electrode current collector 34 and a negative electrode mixture layer 35. The negative electrode current collector 34 includes, for example, a metal material such as copper.

[0033] Negative electrode mixture layer 35 includes a negative electrode active material, a binder, etc. The negative electrode active material is, for example, graphite, etc. The thickness of negative electrode mixture layer 35 is, for example, 0.1 μm or more and 1000 μm or less.

[0034] The negative electrode mixture layer 35 may be formed on either the front or back surface of the negative electrode current collector 34, or may be formed on one surface. The negative electrode sheet 24 has a negative electrode groove portion 40 extending in the direction of the winding axis O, where the negative electrode mixture layer 35 is not formed. A plurality of negative electrode groove portions 40 are formed in the direction in which the negative electrode sheet 24 extends. The negative electrode mixture layer 35 is separated by a plurality of negative electrode groove portions 40. When the negative electrode mixture layer 35 is formed on both the front and back surfaces of the negative electrode current collector 34, the negative electrode groove portion 40 may be formed on either the negative electrode mixture layer 35 on the front and back surfaces, or may be formed on one surface. When the negative electrode groove portion 40 is formed on one surface, it is preferable that the one surface is formed on the side that is the outside of the winding.

[0035] In FIG. 1, the length of negative electrode mixture layer 35 in the Z direction is formed to be longer than the length of positive electrode mixture layer 26.

[0036] 5 is a development view showing the state in which the sheet body 20 is developed and the individual sheets are arranged. The sheet body 20 is formed by overlapping the separator 23 on the negative electrode sheet 24, the positive electrode sheet 22 on the separator 23, and the separator 21 on the positive electrode sheet 22. The positions of the negative electrode sheet 24 and the positive electrode sheet 22 may be interchanged.

[0037] Separator 21 and separator 23 are formed to be long. Separator 21 includes long sides 70 and 71 and short sides 72 and 73. Separator 23 includes long sides 75 and 76 and short sides 77 and 78.

[0038] 5, the electrode body 10 includes an electrode mixture layer 45, which includes a positive electrode mixture layer 26 and a negative electrode mixture layer 35. The electrode body 10 has a starting end S of the wound body of the electrode body 10 and a terminal end E of the wound body of the electrode body 10.

[0039] In the example shown in FIG. 5, the short side 33 and the short side 39 are located at the starting end S. The short side 32 and the short side 38 are located at the terminal end E. The short side 33 and the short side 39 may be shifted in the winding direction D. In this case, in the wound state, the side closer to the winding axis O becomes the starting end S. Similarly, when the short side 32 and the short side 38 are shifted in the winding direction D, the side farther from the winding axis O becomes the terminal end E. In the example shown in FIG. 5, the short sides 73 and 78 of the separators 21 and 23 are also located at the starting end S, and the short sides 72 and 73 are also located at the terminal end E. On the other hand, the separators 21 and 23 may be formed longer in the winding direction D than the positive electrode sheet 22 and the negative electrode sheet 24.

[0040] Fig. 6 is a cross-sectional view showing positive electrode sheet 22, negative electrode sheet 24, separator 21, and separator 23 in Fig. 5. Positive electrode current collector 25 includes main surface 80 and main surface 81. Positive electrode mixture layer 26 includes one-sided positive electrode mixture layer 82 formed on main surface 80, and one-sided positive electrode mixture layer 83 formed on main surface 81.

[0041] Negative current collector 34 includes main surface 84 and main surface 85. Negative mixture layer 35 includes one-sided negative mixture layer 86 formed on main surface 84 and one-sided negative mixture layer 87 formed on main surface 85.

[0042] In the example shown in Fig. 6, the start end S of the inner winding of the wound body is located on the right side, and the end end E of the outer winding of the wound body is located on the left side, and the distance between the grooves on the inner winding on the right side of Fig. 6 is smaller than the distance between the grooves on the outer winding on the left side of Fig. 6. Note that in Fig. 6, the inner winding is designated as D1 and the outer winding is designated as D2, but this is merely an example and is not limited to this.

[0043] The electrode body 10 is formed so as to surround the periphery of the winding axis O from the starting end S. Therefore, in the electrode body 10 in a wound state, the curvature of the inner side of the winding is larger than the curvature of the outer side of the winding, resulting in a large bending stress.

[0044] Therefore, there is a risk of cracks occurring in the electrode mixture layer 45 on the inner side of the winding. On the other hand, in the storage battery cell 1 according to the present embodiment, the electrode sheet has a plurality of groove portions where the electrode mixture layer 45 is not formed, and the interval between the groove portions on the inner side of the winding is smaller than the interval between the groove portions on the outer side of the winding. Therefore, the occurrence of cracks or the like in the electrode mixture layer 45 is suppressed.

[0045] In the positive electrode sheet 22 shown in FIG. 6, the intervals W1, W2, W3 between the positive electrode groove portions 27 on the inner side of the winding are smaller than the intervals W4, W5, W6 between the positive electrode groove portions 27 on the outer side of the winding. In the negative electrode sheet 24, the intervals X1, X2, X3 between the negative electrode groove portions 40 on the inner side of the winding are smaller than the intervals X4, X5, X6 between the negative electrode groove portions 40 on the outer side of the winding.

[0046] Preferably, the interval between the groove portions increases as it goes from the start end portion S to the end end portion E. When providing groove portions in the electrode mixture layer 45, since the amount of the active material contained in the electrode mixture layer 45 decreases, the capacity decreases. Therefore, instead of providing the groove portions uniformly in the electrode mixture layer 45, by providing more groove portions on the inner side of the winding where the bending stress is large, a decrease in capacity is suppressed.

[0047] In the positive electrode sheet 22 shown in FIG. 6, preferably, the interval between the positive electrode groove portions 27 is such that W1 < W2 < W3 < W4 < W5 < W6. In the negative electrode sheet 24, preferably, the interval between the negative electrode groove portions 40 is such that X1 < X2 < X3 < X4 < X5 < X6.

[0048] Preferably, the groove width of the groove portion on the inner side of the winding is smaller than the groove width of the groove portion on the outer side of the winding. This is because on the inner side of the winding where the bending stress is large, even if the groove width of the groove portion is small, it is possible to sufficiently suppress the occurrence of cracks or the like in the electrode mixture layer 45. Also, this is because while providing the groove portions, it is possible to sufficiently secure the area where the electrode mixture layer 45 is formed.

[0049] In the positive electrode sheet 22 shown in FIG. 6, it is preferable that the groove widths Y1, Y2, Y3, Y4 of the positive electrode groove portions 27 on the inner winding side are smaller than the groove widths Y5, Y6, Y7 between the positive electrode groove portions 27 on the outer winding side. In the negative electrode sheet 24, it is preferable that the groove widths Z1, Z2, Z3, Z4 of the negative electrode groove portions 40 on the inner winding side are smaller than the groove widths Z5, Z6, Z7 between the negative electrode groove portions 40 on the outer winding side.

[0050] It is preferable that the groove width of the groove portion increases as it goes from the start end portion S to the end end portion E. This is because the bending stress is greater the closer it is to the start end portion S.

[0051] In the positive electrode sheet 22 shown in FIG. 6, it is preferable that the groove widths of the positive electrode groove portions 27 are such that Y1 < Y2 < Y3 < Y4 < Y5 < Y6 < Y7. In the negative electrode sheet 24, it is preferable that the groove widths of the negative electrode groove portions 40 are such that Z1 < Z2 < Z3 < Z4 < Z5 < Z6 < Z7.

[0052] It is preferable that the positive electrode groove portion 27 and the negative electrode groove portion 40 are formed so as to face each other. When the negative electrode groove portion 40 is provided in the negative electrode sheet 24, the ratio of the negative electrode groove portion 40 facing the positive electrode sheet 22 increases, and there is a risk of lithium precipitation. Therefore, by forming the positive electrode groove portion 27 and the negative electrode groove portion 40 so as to face each other, the ratio of the negative electrode groove portion 40 facing the positive electrode sheet 22 can be suppressed, and lithium precipitation can be suppressed.

[0053] In this case, it is preferable that the groove width of the negative electrode groove portion 40 is smaller than the groove width of the opposing positive electrode groove portion 27. By doing so, lithium precipitation can be further suppressed.

[0054] In FIG. 6, it is preferable that Y1 > Z1, it is preferable that Y2 > Z2, it is preferable that Y3 > Z3, it is preferable that Y4 > Z4, it is preferable that Y5 > Z5, it is preferable that Y6 > Z6, and it is preferable that Y7 > Z7.

[0055] The embodiments disclosed herein should be considered as illustrative and not restrictive in all respects. The present disclosure is defined by the scope of claims, and it is intended to include all modifications within the scope and meaning equivalent to the scope of claims. [Explanation of symbols]

[0056] 1 storage cell, 2 top plate portion, 3,19 peripheral wall, 5 first end portion, 6 second end portion, 7 through hole, 10,10A electrode body, 11 case, 12 positive electrode current collector member, 13 negative electrode current collector member, 14,15 insulating member, 16 positive electrode terminal, 17 top plate, 18 bottom plate, 20 sheet body, 21,23 separator, 22 positive electrode sheet, 24 negative electrode sheet, 25 positive electrode current collector plate, 26,82,83 positive electrode mixture layer, 27 positive electrode groove portion, 30,31,36,37,70,71,75,76 long side, 32,33,38,39,72,73,77,78 short side, 34 negative electrode current collector plate, 35,86,87 negative electrode mixture layer, 40 negative electrode groove portion, 43 Hollow portion, 45 electrode composite layer, 50 flat plate, 51 shaft, 80, 81, 84, 85 main surfaces, D winding direction, D1 inner winding side, D2 outer winding side, E end portion, O winding axis, S starting end portion.

Claims

1. an electrode body in which the sheet body is wound so as to surround a winding axis; A case in which the electrode body is housed; Equipped with The sheet body includes an electrode sheet and a separator, The electrode sheet includes a current collector plate and an electrode mixture layer formed on the current collector plate, the electrode sheet has a groove portion extending in the winding axis direction and in which the electrode mixture layer is not formed, The groove portion is formed in a plurality of portions in a direction in which the electrode sheet extends, A storage cell, wherein the spacing between the grooves on the inner side of the winding is smaller than the spacing between the grooves on the outer side of the winding.

2. The electrode body has a starting end of a wound body of the electrode body and a terminal end of the wound body of the electrode body, The energy storage cell according to claim 1 , wherein the interval between the grooves increases from the starting end toward the terminal end.

3. The energy storage cell according to claim 1 , wherein a groove width of the groove portion on the inner side of the winding is smaller than a groove width of the groove portion on the outer side of the winding.

4. The electrode sheet includes a positive electrode sheet and a negative electrode sheet, The positive electrode sheet includes a positive electrode current collector and a positive electrode mixture layer formed on the positive electrode current collector, the positive electrode sheet has a positive electrode groove portion extending in the winding axis direction and in which the positive electrode mixture layer is not formed, The negative electrode sheet includes a negative electrode current collector and a negative electrode mixture layer formed on the negative electrode current collector, the negative electrode sheet has a negative electrode groove portion extending in the winding axis direction and in which the negative electrode mixture layer is not formed, The energy storage cell according to claim 1 , wherein the positive electrode groove portion and the negative electrode groove portion are formed so as to face each other.

5. The energy storage cell according to claim 4 , wherein a groove width of the negative electrode groove portion is smaller than a groove width of the opposing positive electrode groove portion.

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