Power storage device

Abstract

To provide a power storage device in which an electrolyte solution can easily permeate into a wound electrode body accommodated in a case.SOLUTION: A power storage device includes a wound electrode body having a winding axis extending in a predetermined direction and configured in such a way that a multilayer body including a band-shaped negative electrode, a band-shaped positive electrode, and a band-shaped separator is wound spirally around the winding axis, and a case that accommodates an electrolyte solution and the wound electrode body. The wound electrode body includes an outer peripheral surface facing the case. The wound electrode body includes a first hole extending from the outer peripheral surface toward the winding axis.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a power storage device.

Background Art

[0002] Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 4-184871 (Patent Document 1), a battery is known that includes a wound electrode body configured by laminating a strip-shaped negative electrode and a strip-shaped positive electrode with a strip-shaped separator interposed therebetween and then winding the laminate in a spiral around a winding axis in a battery can.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the wound electrode body as shown in Patent Document 1 increases in size, the electrolytic solution enclosed in the case (battery can) becomes difficult to penetrate into the wound electrode body.

[0005] The present disclosure provides a power storage device in which an electrolytic solution easily penetrates into a wound electrode body housed in a case.

Means for Solving the Problems

[0006] According to an aspect of the present disclosure, a power storage device includes a wound electrode body configured by winding a laminate including a strip-shaped positive electrode, a strip-shaped negative electrode, and a strip-shaped separator in a spiral around a winding axis extending in a predetermined direction, a case that houses the electrolytic solution and the wound electrode body, and the wound electrode body has an outer peripheral surface facing the case. A first hole extending in a direction from the outer peripheral surface toward the winding axis is formed in the wound electrode body.

[0007] According to the above configuration, the electrolytic solution can penetrate from the outer peripheral surface side of the wound electrode body into the inside of the wound electrode body through the first holes. Therefore, according to the power storage device, compared with a configuration in which the first holes are not formed in the wound electrode body, it becomes easier for the electrolytic solution to penetrate into the inside of the wound electrode body.

[0008] Preferably, the first holes include a plurality of positive electrode through-holes formed in the positive electrode, a plurality of negative electrode through-holes formed in the negative electrode, and a plurality of separator through-holes formed in the separator. The opening area of each separator through-hole is smaller than the opening area of each negative electrode through-hole and the opening area of each positive electrode through-hole.

[0009] According to the above configuration, compared with the case where the opening area of each separator through-hole is larger than the opening area of each negative electrode through-hole and the opening area of each positive electrode through-hole, the risk of short circuit between the negative electrode and the positive electrode through the separator through-holes can be reduced.

[0010] Preferably, the opening area of each positive electrode through-hole is larger than the opening area of each negative electrode through-hole.

[0011] According to the above configuration, the risk of short circuit between the negative electrode and the positive electrode through the separator through-holes can be further reduced.

[0012] Preferably, the case has an inner peripheral surface facing the outer peripheral surface. A groove portion extending in a predetermined direction is formed on the inner peripheral surface. The groove portion faces the first holes.

[0013] According to the above configuration, the exchange of the electrolytic solution and gas is possible between the groove portion and the first holes. Therefore, according to the power storage device, compared with a configuration without the groove portion, it is excellent in the liquid injection property of the electrolytic solution and the exhaust property of the gas generated in the wound electrode body.

[0014] Preferably, the case has a main body having an upper end portion and the groove portion formed up to the upper end portion, and a lid having a second hole penetrating in a predetermined direction and attached to the main body from above. The second hole is located above the groove portion. The case further includes a closing member for closing the second hole.

[0015] According to the above configuration, since the second hole is located above the groove portion, by injecting the electrolytic solution from the second hole, the electrolytic solution can be easily guided to the groove portion.

Advantages of the Invention

[0016] According to the above configuration, it becomes easier for the electrolytic solution to penetrate into the wound electrode body housed in the case.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, the same members are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0019] FIG. 1 is an exploded perspective view for explaining the configuration of a power storage device 10 according to the present embodiment. As shown in FIG. 1, the power storage device 10 includes a wound electrode body 100 and a case 200. The power storage device 10 is mounted on an electric vehicle such as a hybrid vehicle that can travel using the power of at least one of a motor and an engine, or an electric vehicle that travels with a driving force obtained by electric energy.

[0020] The wound electrode body 100 has an outer peripheral surface 150 facing the case 200. A plurality of holes 180 are formed in the wound electrode body 100. In this example, in the wound electrode body 100, four holes 180 are formed in a row in the vertical direction (Z direction). On the outer peripheral surface 150, the open ends 180a of the respective holes 180 are arranged in a row in the Z direction.

[0021] The case 200 houses the wound electrode body 100 and the electrolytic solution. The case 200 includes a main body 201 and a lid 202. The main body 201 has a body portion 210 and a bottom portion 219. The case 200 is also referred to as a "cell case".

[0022] In this example, the bottom portion 219 is circular when viewed from above the main body 201. The body portion 210 extends in the direction from the bottom portion 219 toward the lid 202 (the direction of Z1 in the Z direction in the figure). The body portion 210 is cylindrical.

[0023] The body portion 210 has an inner peripheral surface 211, an outer peripheral surface 212, an upper end portion 213, and a lower end portion 214. The inner peripheral surface 211 faces the wound electrode body 100. The inner peripheral surface 211 faces the outer peripheral surface 150 of the wound electrode body 100. The upper end portion 213 abuts against the lid 202. The lower end portion 214 is continuous with the bottom portion 219.

[0024] A groove portion 215 extending in the vertical direction (the Z direction in the figure) is formed in the inner peripheral surface 211. The groove portion 215 extends from the lower end portion 214 to the upper end portion 213. The groove portion 215 faces each of the holes 180 formed in the wound electrode body 100. Specifically, the groove portion 215 faces the open end 180a of each hole 180. More specifically, the wound electrode body 100 is fixed in position within the case 100 such that the open end 180a faces the groove portion 215. Since the groove portion 215 is formed in a part of the inner peripheral surface 211 of the case 200, the open end 180a is not blocked by the inner peripheral surface 211 of the case 200.

[0025] The lid 202 has an external terminal 221 connected to the wound electrode body 100. A through hole 222 for injecting an electrolytic solution into the case 200 (specifically, the main body 201) is formed in the lid 202. The through hole 222 functions as a liquid injection port. The through hole 222 extends in the Z direction. The through hole 222 is located above the groove portion 215. Thereby, the electrolytic solution injected into the main body 201 through the through hole 222 can be surely guided to the groove portion 215. Specifically, the electrolytic solution can be dropped downward (in the direction of Z2) along the inner peripheral surface 211 along the groove portion 215 and around the groove portion 215.

[0026] The lid 202 further has a cap 223 for closing the through hole 222. The lid 202 is attached to the main body 201 from above. The cap 223 can prevent the leakage of the electrolytic solution from the case 200.

[0027] The power storage device 10 is manufactured through the following steps. The wound electrode body 100 is housed in the main body 201 of the case 200. Then, the lid 202 is placed over the main body 201. Further, the lid 202 is fixed to the main body 201. Next, the electrolytic solution is injected into the case 200 through the through hole 222. After the injection of the electrolytic solution, the through hole 222 is sealed with the cap 223.

[0028] Note that the Z direction is an example of the "predetermined direction" of the present disclosure. The direction of R1 among the R directions is an example of the "direction from the outer peripheral surface toward the winding axis" of the present disclosure. The hole 180 is an example of the "first hole" of the present disclosure. The through hole 222 is an example of the "second hole" of the present disclosure. The cap 223 is an example of the "closing member" of the present disclosure.

[0029] Next, based on FIGS. 2 to 4, the details of the wound electrode body 100 will be described. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1. FIG. 3 is a perspective view of the wound electrode body 100.

[0030] As shown in FIGS. 2 and 3, the wound electrode body 100 has a winding axis Ax extending in the Z direction. The wound electrode body 100 is formed by winding a laminate including a strip-shaped positive electrode 110, a strip-shaped negative electrode 120, and a strip-shaped separator 130 in a spiral around the winding axis Ax.

[0031] Specifically, the separator 130 includes a first separator 132 and a second separator 134. The laminate is formed by stacking the negative electrode 120, the first separator 132, the positive electrode 110, and the second separator 134 in this order. The laminate is wound in the direction of arrow D in FIG. 3 (the longitudinal direction L of the laminate).

[0032] As shown in FIG. 2, the positive electrode 110 includes a positive electrode current collector foil 112 and a positive electrode active material layer 114. The positive electrode current collector foil 112 may contain, for example, Al or the like. The positive electrode current collector foil 112 includes a first region 112a and a second region 112b. The positive electrode active material layer 114 is disposed in the first region 112a. The positive electrode active material layer 114 may contain, for example, a lithium nickel composite oxide or the like.

[0033] The second region 112b is adjacent to the first region 112a. The second region 112b is disposed at an end in the direction of the winding axis Ax. The second region 112b has a plurality of tabs. The plurality of tabs are separated in the winding direction of the wound electrode body 100 (direction D in FIG. 3). For example, a plurality of tabs may be welded to the second region 112b. For example, a part of the second region 112b may be processed into tabs. Each tab is tilted inward in the radial direction. The "radial direction" is the R direction. The outer surface of each tab forms a substantially flat surface. Each tab is connected to the positive electrode current collector plate 410. Each tab may be welded to the positive electrode current collector plate 410.

[0034] The negative electrode 120 includes a negative electrode current collector foil 122 and a negative electrode active material layer 124. The negative electrode current collector foil 122 may contain, for example, Cu, Ni, etc. The negative electrode current collector foil 122 includes a first region 122a and a second region 122b. The negative electrode active material layer 124 is disposed in the first region 122a. The negative electrode active material layer 124 may contain, for example, graphite, Si, SiO, etc.

[0035] The second region 122b is adjacent to the first region 122a. The second region 122b is disposed at an end in the direction of the winding axis Ax. The second region 122b has a plurality of tabs. The plurality of tabs are separated in the winding direction of the wound electrode body 100. Each tab is tilted inward in the radial direction. The outer surface of each tab forms a substantially flat surface. Each tab is connected to the negative electrode current collector plate 420. Each tab may be welded to the negative electrode current collector plate 420. Each tab may be welded to the bottom 219 of the case 200.

[0036] The separator 130 has electrical insulation. The separator 130 electrically separates the positive electrode 110 from the negative electrode 120. In the radial direction, the separator 130 is disposed between the positive electrode 110 and the negative electrode 120. The separator 130 is porous. The electrolyte can penetrate the separator 130. The separator 130 may contain, for example, a porous membrane made of resin, etc.

[0037] Note that the outermost layer of the wound electrode body 100 may be an electrode or a separator 130. The "outermost layer" refers to the member located outermost in the radial direction at the end of the winding of the wound electrode body 100 among the positive electrode 110, the negative electrode 120, and the separator 130. In the present embodiment, the outermost layer of the wound electrode body 100 is a negative electrode as shown in FIG. 3. That is, the outermost layer of the wound electrode body 100 is the negative electrode 120. More specifically, the outermost layer is the negative electrode active material layer 124, but may also be the negative electrode current collector foil 122. The outermost layer is not limited to the negative electrode 120 and may also be the positive electrode 110.

[0038] The outermost layer is in contact with the case 200. Specifically, the outermost layer is in close contact with the inner peripheral surface 211 of the main body 201. The portion of the case 200 that contacts the outermost layer (i.e., the inner peripheral surface 211) is made of a conductive material.

[0039] The electrolytic solution is a liquid electrolyte. The electrolytic solution contains a solute and a solvent. The electrolytic solution may further contain any additives. The solute contains a supporting electrolyte. The solute may contain, for example, at least one selected from the group consisting of LiPF6, LiBF4, LiN(SO2F)2, LiN(SO2CF3)2, LiB(C2O4)2, LiPO2F2, and FSO3Li. The concentration of the solute may be, for example, from 0.5 to 2.0 mol / L.

[0040] Referring to FIG. 2, as described above, a plurality of holes 180 are formed in the wound electrode body 100 (see FIG. 2). Each hole 180 extends in the radial direction (the direction of R1 among the R directions) from the outer peripheral surface 150 of the wound electrode body 100 toward the winding axis Ax. In this example, each hole 180 is substantially cylindrical. However, the shape of each hole 180 is not limited to a cylindrical shape and may be a rectangular shape or the like.

[0041] In this example, each hole 180 extends near the winding axis Ax of the wound electrode body 100. Each hole 180 reaches the innermost layer of the wound electrode body 100. However, it is not limited to this, and each hole 180 does not necessarily have to reach the innermost layer of the wound electrode body 100. In this example, the axis Bx of each hole 180 is perpendicular to the winding axis Ax. However, it is not limited to this, and the axis Bx may be inclined, for example, downward (in the direction of Z2) as it approaches the winding axis Ax.

[0042] FIG. 4 is a diagram for explaining the elements constituting the hole 180. Referring to FIG. 4, as described above, the wound electrode body 100 has a negative electrode 120, a first separator 132, a positive electrode 110, and a second separator 134. The end S is the start side of winding. The end E is the end side of winding.

[0043] The hole 180 includes a plurality of through-holes 129 formed in the negative electrode 120, a plurality of through-holes 119 formed in the positive electrode 110, a plurality of through-holes 329 formed in the first separator 132, and a plurality of through-holes 349 formed in the second separator 134.

[0044] In the direction of R2 shown in FIG. 2 (the direction opposite to R1), the through-hole 349, the through-hole 119, the through-hole 329, and the through-hole 129 are repeatedly overlapped in this order, thereby forming one hole 180.

[0045] That is, in the negative electrode 120, the first separator 132, the positive electrode 110, and the second separator 134, when the laminate in which these are stacked is wound in a spiral shape, the through-holes 349, 119, 329, and 129 are formed such that the four through-holes 349, 119, 329, and 129 overlap each other.

[0046] From the viewpoint of preventing short circuit between the negative electrode 120 and the positive electrode 110, it is preferable that the opening areas of the through-holes 329 and 349 of the first and second separators 132 and 134 are smaller than the opening area of the through-hole 129 of the negative electrode 120 and the opening area of the through-hole 119 of the positive electrode 110. Further, from the viewpoint of preventing short circuit, it is preferable that the opening area of the through-hole 119 of the positive electrode 110 is larger than the opening area of the through-hole 129 of the negative electrode 120. That is, among the through-holes 119, 129, 329, and 349, it is preferable that the opening area of the through-hole 119 is the largest, and the opening areas of the through-holes 329 and 349 are the smallest. Note that the present invention is not limited to this, and the opening area of the through-hole 129 may be made larger than the opening area of the through-hole 119.

[0047] Furthermore, the sum of the opening areas at the opening ends 180a of the four holes 180 is larger than the opening area of the through-hole 222 of the lid 202.

[0048] The through-hole 119 is an example of the "positive electrode through-hole" of the present disclosure. The through-hole 129 is an example of the "negative electrode through-hole" of the present disclosure. The through-holes 329 and 349 are examples of the "separator through-holes" of the present disclosure.

[0049] <Advantages> (1) As described above, the power storage device 10 includes, as shown in FIG. 1, a wound electrode body 100, and a case 200 that houses the electrolytic solution and the wound electrode body 100. As shown in FIGS. 2 and 3, the wound electrode body 100 has a winding axis Ax extending in the Z direction, and is configured by winding a laminate including a strip-shaped positive electrode 110, a strip-shaped negative electrode 120, and a strip-shaped separator 130 around the winding axis Ax in a spiral shape. The wound electrode body 100 has an outer peripheral surface 150 facing the case 200. A hole 180 extending in the direction from the outer peripheral surface 150 toward the winding axis Ax (the direction of R1) is formed in the wound electrode body 100.

[0050] According to such a configuration, the electrolytic solution can penetrate from the outer peripheral surface 150 side of the wound electrode body 100 into the wound electrode body 100 through the hole 180. Therefore, according to the power storage device 10, compared with a configuration in which the hole 180 is not formed in the wound electrode body, it becomes easier for the electrolytic solution to penetrate (impregnate) into the wound electrode body 100. Further, the hole 180 can serve as an absorption allowance when the wound electrode body 100 expands and contracts.

[0051] (2) As shown in FIG. 4, the hole 180 has a plurality of through holes 119 formed in the positive electrode 110, a plurality of through holes 129 formed in the negative electrode 120, and a plurality of through holes 329, 349 formed in the separator 130. The opening area of each of the through holes 329, 349 is smaller than the opening area of each of the through holes 129 and the opening area of each of the through holes 119.

[0052] According to such a configuration, compared with the case where the opening area of each of the through holes 329, 349 is larger than the opening area of each of the through holes 129 and the opening area of each of the through holes 119, the risk of short circuit between the positive electrode 110 and the negative electrode 120 through the through holes 329, 349 formed in the separator 130 can be reduced.

[0053] (3) As shown in FIG. 4, the opening area of the through hole 119 is larger than the opening area of the through hole 129.

[0054] According to such a configuration, compared with the case where the opening area of the through hole 119 and the opening area of the through hole 129 are the same, the risk of short circuit between the positive electrode 110 and the negative electrode 120 through the through holes 329 and 349 formed in the separator 130 can be further reduced.

[0055] (4) As shown in FIG. 1, the case 200 has an inner peripheral surface 211 facing the outer peripheral surface 150 of the wound electrode body 100. A groove portion 215 extending in the Z direction is formed on the inner peripheral surface 211. The groove portion 215 faces the hole 180.

[0056] According to such a configuration, the exchange of the electrolytic solution and the gas is possible between the groove portion 215 and the hole 180. Specifically, the electrolytic solution can be easily introduced into the hole 180 through the groove portion 215. Further, the gas accumulated in the hole 180 can be guided to the groove portion 215. Therefore, according to the power storage device 10, the liquid injection property of the electrolytic solution and the exhaust property of the gas generated in the wound electrode body 100 are superior to those of a configuration without the groove portion 215.

[0057] (5) As shown in FIG. 1, the case 200 has a main body 201 having an upper end portion 213 and the groove portion 215 formed up to the upper end portion 213, and a lid 202 in which a through hole 222 penetrating in the Z direction is formed and which is attached to the main body 201 from above. The through hole 222 is located above the groove portion 215. The power storage device 10 further includes a cap 223 that closes the through hole 222.

[0058] According to such a configuration, since the through hole 222 is located above the groove portion 215, the electrolytic solution can be easily guided to the groove portion 215 by injecting the electrolytic solution through the through hole 222.

[0059] (6) As shown in FIGS. 1 and 2, a plurality of holes 180 are formed in the wound electrode body 100. Therefore, the liquid injection property and the gas exhaust property in case of abnormality are superior to those in the case where there is one hole 180.

[0060] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims be included.

Explanation of Reference Numerals

[0061] 10 Power storage device, 100 Wound electrode body, 110 Positive electrode, 112 Positive electrode current collector foil, 112a, 122a First region, 112b, 122b Second region, 114 Positive electrode active material layer, 119, 129, 222, 329, 349 Through hole, 120 Negative electrode, 122 Negative electrode current collector foil, 124 Negative electrode active material layer, 130 Separator, 132 First separator, 134 Second separator, 150, 212 Outer peripheral surface, 180 Hole, 180a Open end, 200 Case, 201 Body, 202 Lid, 210 Barrel portion, 211 Inner peripheral surface, 213 Upper end portion, 214 Lower end portion, 215 Groove portion, 219 Bottom portion, 221 External terminal, 223 Cap, 410 Positive electrode current collector plate, 420 Negative electrode current collector plate, Ax Winding shaft, Bx Axis.

Claims

1. A wound electrode body formed by winding a laminate including a winding shaft extending in a predetermined direction, a strip-shaped positive electrode, a strip-shaped negative electrode, and a strip-shaped separator in a spiral around the winding shaft, a case that houses an electrolytic solution and the wound electrode body, and the wound electrode body has an outer peripheral surface facing the case, a power storage device, wherein a first hole extending in a direction from the outer peripheral surface toward the winding shaft is formed in the wound electrode body.

2. The first hole has a plurality of positive electrode through holes formed in the positive electrode, a plurality of negative electrode through holes formed in the negative electrode, and a plurality of separator through holes formed in the separator, The power storage device according to claim 1, wherein an opening area of each of the separator through holes is smaller than an opening area of each of the negative electrode through holes and an opening area of each of the positive electrode through holes.

3. The power storage device according to claim 2, wherein an opening area of each of the positive electrode through holes is larger than an opening area of each of the negative electrode through holes.

4. The case has an inner peripheral surface facing the outer peripheral surface, a groove portion extending in the predetermined direction is formed in the inner peripheral surface, The power storage device according to claim 1, wherein the groove portion faces the first hole.

5. The case has a main body having an upper end portion and the groove portion formed up to the upper end portion, and a lid having a second hole penetrating in the predetermined direction and attached to the main body from above, the second hole is located above the groove portion, The power storage device according to claim 4, further comprising a closing member that closes the second hole.

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