Energy storage cell

Abstract

To provide a power storage cell capable of suppressing gas retention within an electrode body.SOLUTION: A power storage cell includes an electrode assembly 100 and a cell case that houses the electrode assembly. The electrode assembly 100 includes a plurality of electrodes 110, 120 arranged in one direction, and a separator 130 formed in a zigzag shape. The separator 130 includes a plurality of intermediate portions 132a interposed between a pair of electrodes adjacent to each other in one direction, an upper folded portion 132b, and a lower folded portion 132c. At least one of the upper folded portion 132b and the lower folded portion 132c is provided with a discharge hole H for discharging gas.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Japanese Patent Application Laid-Open Publication No. 2016-143550 discloses a battery cell including a zigzag laminate structure and an exterior body. The zigzag laminate structure includes multiple positive electrode plates, multiple negative electrode plates, and a separator arranged in a zigzag pattern between the positive and negative electrode plates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-143550 Summary of the Invention [Problem to be solved by the invention]

[0004] In the battery cell described in JP 2016-143550 A, when gas is generated in the zigzag laminate structure, there is a concern that the gas may remain within the zigzag laminate structure.

[0005] An object of the present disclosure is to provide an electricity storage cell that can suppress gas retention within an electrode body. [Means for solving the problem]

[0006] A storage cell according to one aspect of the present disclosure comprises an electrode assembly and a cell case that houses the electrode assembly, wherein the electrode assembly comprises a plurality of electrodes arranged side by side in one direction, and a separator that is formed in a zigzag shape and provides insulation between each of the plurality of electrodes, wherein the separator includes a plurality of intervening portions interposed between a pair of electrodes adjacent to each other in the one direction, an upper fold portion that connects an upper end of one of the plurality of intervening portions to an upper end of a portion of the plurality of intervening portions that is adjacent to the one intervening portion on one side in the one direction, and a lower fold portion that connects a lower end of one of the plurality of intervening portions to a lower end of a portion of the plurality of intervening portions that is adjacent to the one intervening portion on the other side in the one direction, and at least one of the upper fold portion and the lower fold portion is provided with a discharge hole for discharging gas. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide an energy storage cell that can suppress the accumulation of gas within the electrode body. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view schematically illustrating a storage cell according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view of the storage cell shown in FIG. [Figure 3] FIG. [Figure 4] FIG. 2 is a plan view of the separator before it is formed into a zigzag shape. [Figure 5] 10A and 10B are perspective views schematically illustrating a process of connecting an electrode tab and a current collecting tab. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present disclosure will be described with reference to the accompanying drawings, in which the same or corresponding elements are designated by the same reference numerals.

[0010] Fig. 1 is a perspective view schematically illustrating a storage cell according to an embodiment of the present disclosure, and Fig. 2 is a cross-sectional view of the storage cell shown in Fig. 1.

[0011] As shown in FIGS. 1 and 2, the energy storage cell 1 includes an electrode assembly 100, a cell case 200, an electrolyte (not shown), a pair of external terminals 300, a pair of connecting members 400, and an insulating member 500.

[0012] 3 is a cross-sectional view of the electrode assembly 100. As shown in FIG. 3, the electrode assembly 100 includes a plurality of electrodes 110, 120 and a separator .

[0013] 3, the plurality of electrodes 110, 120 are arranged side by side in one direction (the left-right direction in FIG. 3). The plurality of electrodes 110, 120 includes a plurality of positive electrodes 110 and a plurality of negative electrodes 120.

[0014] Each positive electrode 110 is formed in a rectangular shape that is long in the width direction (a direction perpendicular to both one direction and the up-down direction). Each positive electrode 110 has a positive electrode current collector foil 112 and positive electrode active material layers 114 provided on both sides of the positive electrode current collector foil 112. As shown in FIGS. 2 and 5, the positive electrode current collector foil 112 has a positive electrode tab 112p on which the positive electrode active material layer 114 is not provided. The positive electrode tab 112p protrudes toward one side in the width direction (a direction perpendicular to the plane of the paper in FIG. 3).

[0015] Each negative electrode 120 is formed in a rectangular shape that is long in the width direction. Each negative electrode 120 has a negative electrode current collector foil 122 and a negative electrode active material layer 124 provided on both sides of the negative electrode current collector foil 122. As shown in Figs. 2 and 5, the negative electrode current collector foil 122 has a negative electrode tab 122n on which the negative electrode active material layer 124 is not provided. The negative electrode tab 122n protrudes toward the other side in the width direction.

[0016] The separator 130 provides insulation between the positive electrode 110 and the negative electrode 120. The separator 130 is made of an insulating material and has minute voids that allow ions to pass through. As shown in Fig. 3, the separator 130 is formed in a zigzag shape.

[0017] Fig. 4 is a plan view of the separator 130 before it is formed into a zigzag shape. As shown in Fig. 4, the separator 130 has a rectangular shape before it is formed into a zigzag shape. The separator 130 is disposed between the electrodes 110, 120 while being formed into a zigzag shape. As shown in Fig. 3, the separator 130 has a plurality of intervening portions 132a, a plurality of upper folded portions 132b, a plurality of lower folded portions 132c, and an outermost covering portion 132d.

[0018] Each intervening portion 132a is interposed between a pair of electrodes 110, 120 adjacent to each other in one direction. In other words, each intervening portion 132a has the function of insulating between the positive electrode 110 and the negative electrode 120. Each intervening portion 132a is formed of a rectangular region.

[0019] Each upper folded portion 132b connects the upper end of one of the plurality of intervening portions 132a to the upper end of another of the plurality of intervening portions 132a that is adjacent to the one intervening portion 132a on one side in one direction. In this embodiment, the upper folded portion 132b is disposed above the positive electrode 110.

[0020] Each lower folded portion 132c connects the lower end of one of the plurality of intervening portions 132a to the lower end of another of the plurality of intervening portions 132a that is adjacent to the one intervening portion on the other side in one direction. In this embodiment, the lower folded portion 132c is disposed below the negative electrode 120. In other words, the negative electrode 120 is disposed on the lower folded portion 132c.

[0021] The outermost covering portion 132d collectively covers the upper folded portions 132b and the lower folded portions 132c. More specifically, the outermost covering portion 132d collectively covers all of the electrodes 110, 120, all of the intervening portions 132a, all of the upper folded portions 132b, and all of the lower folded portions 132c while being wound around a central axis parallel to the width direction. An end 132e (see FIGS. 3 and 4) of the outermost covering portion 132d is set in a range that does not overlap with the positive electrode active material layer 114 and the negative electrode active material layer 124 in one direction. In this embodiment, the end 132e of the outermost covering portion 132d is provided below the electrodes 110, 120.

[0022] 3 and 4, each upper folded portion 132b, each lower folded portion 132c, and the outermost covering portion 132d is provided with a discharge hole H for discharging gas generated within the electrode body 100. As shown in Fig. 3, the discharge hole H provided in the outermost covering portion 132d overlaps in the vertical direction with the discharge hole H provided in the upper folded portion 132b and the discharge hole H provided in the lower folded portion 132c. Each discharge hole H is formed by laser irradiation or the like.

[0023] As shown in Fig. 4, the multiple discharge holes H aligned along the width direction (left-right direction in Fig. 4) are preferably provided at equal intervals. The multiple discharge holes H aligned along the longitudinal direction (up-down direction in Fig. 4) of the separator 130 before it is formed into a zigzag shape are preferably provided at equal intervals. The dimension W between a pair of adjacent discharge holes H in the width direction is preferably set equal to the dimension L between a pair of adjacent discharge holes H in the longitudinal direction of the separator 130. For example, the diameter of each discharge hole H is set to 100 µm, and the dimensions W and L are set to 500 µm.

[0024] The cell case 200 houses the electrode assembly 100. The cell case 200 houses an electrolyte (not shown). The cell case 200 is sealed. The cell case 200 has a case body 210 and a lid 220.

[0025] The case body 210 has an opening that opens upward. The case body 210 is made of a metal such as aluminum. As shown in FIG. 2, the case body 210 has a bottom wall 212 and a peripheral wall 214. The bottom wall 212 is formed in a rectangular, flat plate shape. The peripheral wall 214 stands upright from the bottom wall 212. The peripheral wall 214 is formed in a square cylindrical shape. The length of the peripheral wall 214 in the width direction is longer than the length of the peripheral wall 214 in the thickness direction. The length of the peripheral wall 214 in the height direction is longer than the length of the peripheral wall 214 in the thickness direction.

[0026] The lid 220 closes the opening of the case body 210. The lid 220 is connected to the opening by welding or the like. The lid 220 is formed in a flat plate shape. The lid 220 is made of a metal such as aluminum. The lid 220 has a pressure release valve 222 and a sealing member 224.

[0027] Pressure release valve 222 is formed in the center of lid 220. Pressure release valve 222 is formed to rupture when the internal pressure of cell casing 200 reaches or exceeds a predetermined pressure. When pressure release valve 222 ruptures, gas within cell casing 200 is released to the outside of cell casing 200 through pressure release valve 222, thereby reducing the internal pressure of cell casing 200.

[0028] The sealing member 224 seals a liquid filling port h formed in the lid 220. The liquid filling port h is a through-hole for injecting an electrolyte into the cell case 200 during the manufacturing process of the energy storage cell 1. The liquid filling port h is sealed by the sealing member 224 after the electrolyte is injected into the case body 210 through the liquid filling port h.

[0029] A pair of external terminals 300 are fixed on the cell case 200. One of the pair of external terminals 300 is a positive electrode external terminal, and the other is a negative electrode external terminal. Each external terminal 300 is fixed to the upper surface of the lid 220 via an upper insulating part 510, which will be described later. Each external terminal 300 is made of a metal such as aluminum. Each external terminal 300 is formed, for example, in the shape of a rectangular parallelepiped. A bus bar (not shown) is connected to each external terminal 300 by welding or the like.

[0030] The pair of connecting members 400 connect the plurality of electrode tabs 112p, 122n to the external terminals 300. One connecting member 400 connects the plurality of positive electrode tabs 112p to the positive electrode external terminals 300, and the other connecting member 400 connects the plurality of negative electrode tabs 122n to the negative electrode external terminals 300. Since the pair of connecting members 400 have substantially the same structure, only one of the connecting members 400 will be described below.

[0031] The connecting member 400 includes a current collecting tab 410 , a sub-tab 420 , and a connecting pin 430 .

[0032] The current collecting tab 410 has a side portion 412 and an upper portion 414. The side portion 412 is located on a side of the electrode assembly 100 in the width direction. The upper portion 414 is located above the electrode assembly 100. The upper portion 414 extends from the upper end of the side portion 412 toward the inside in the width direction.

[0033] The subtabs 420 connect the multiple positive electrode tabs 112p to the current collecting tab 410. One end 422 of the subtab 420 is connected to the multiple positive electrode tabs 112p by welding or the like, and the other end 424 of the subtab 420 is connected to the side portion 412 of the current collecting tab 410 by welding or the like.

[0034] The connecting pin 430 connects the current collecting tab 410 and the external terminal 300. The connecting pin 430 connects the upper part 414 and the external terminal 300. Specifically, the lower end of the connecting pin 430 is inserted into a through hole provided in the upper part 414 and connected to the upper part 414 by welding or the like, and the upper end of the connecting pin 430 is inserted into a through hole provided in the external terminal 300 and connected to the external terminal 300 by welding, crimping or the like.

[0035] The insulating member 500 provides insulation between the cell casing 200 and the connecting member 400. The insulating member 500 has an upper insulating portion 510, a lower insulating portion 520, an insulator 530, and an insulating plate 540.

[0036] The upper insulating part 510 is fixed to the upper surface of the lid 220. The upper insulating part 510 is disposed between the lid 220 and the external terminal 300. The upper insulating part 510 has an insertion hole through which the connecting pin 430 is inserted.

[0037] The lower insulating part 520 is fixed to the lower surface of the lid 220. The lower insulating part 520 is disposed between the lid 220 and the upper part 414 and the lower part of the connecting pin 430. The lower insulating part 520 has an insertion hole through which the connecting pin 430 is inserted.

[0038] The insulator 530 is disposed between the connecting pin 430 and the lid 220. The insulator 530 is formed in a cylindrical shape and surrounds the connecting pin 430.

[0039] The insulating plate 540 is fixed to the lower surface of the upper part 414. The insulating plate 540 is disposed above the electrode assembly 100. Through holes are provided in the insulating plate 540 in a portion located below the pressure release valve 222 and a portion located below the liquid injection port h.

[0040] Next, the manufacturing process of the energy storage cell 1 will be described with reference to FIG. 5 and other figures.

[0041] First, the separator 130 is folded zigzag using a roller (not shown), with the electrodes 110, 120 alternately arranged between a pair of intervening portions 132a. The roller is formed in a crown shape. That is, the roller is formed in a shape that increases in diameter from the end portion toward the center in the direction of the roller's rotation axis. In this way, when the separator 130 is folded zigzag, the formation of wrinkles in the center of the separator 130 in the width direction (the direction parallel to the roller's rotation axis) is suppressed.

[0042] Then, after the outermost covering portion 132d of the separator 130 is wound, the end 132e is connected to the outermost covering portion 132d by an appropriate means. Note that the discharge hole H is not shown in FIG.

[0043] 5, one end 422 of the sub-tab 420 is connected to the multiple electrode tabs 112p, 122n by welding or the like. Thereafter, the one end 422 and the multiple electrode tabs 112p, 122n are bent so that the one end 422 of the sub-tab 420 contacts the side portion 412 of the current collecting tab 410.

[0044] Next, the peripheral and bottom surfaces of the multiple electrodes 110, 120 and separator 130 are collectively covered with an insulating film (not shown), and then the electrode assembly 100 is inserted into the case body 210. Then, the peripheral edge of the lid 220 is connected to the opening of the case body 210 by welding or the like.

[0045] Thereafter, the electrolyte is supplied into the cell case 200 through the liquid filling port h, and the liquid filling port h is sealed with the sealing member 224.

[0046] As described above, in the energy storage cell 1 of this embodiment, the upper folded portion 132b and the lower folded portion 132c of the separator 130 are provided with the exhaust holes H, so that gas generated within the electrode assembly 100 is effectively exhausted to the outside of the electrode assembly 100 through the exhaust holes H. This prevents gas from accumulating within the electrode assembly 100.

[0047] In the above embodiment, the discharge holes H are provided in the upper folded portion 132b and the lower folded portion 132c, but the discharge holes H may be provided in either the upper folded portion 132b or the lower folded portion 132c. Also, the discharge holes H provided in the outermost covering portion 132d may be omitted.

[0048] The electrode assembly 100 may further include a liquid retention member (not shown) that is a member different from the separator 130 and is capable of retaining an electrolyte. The liquid retention member is made of, for example, a porous material. The liquid retention member is provided at the ends of the multiple electrodes 110, 120 and the separator 130 in the width direction (below the electrode tabs 112p, 122n).

[0049] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0050] [Aspect 1] An electrode body; a cell case that houses the electrode assembly, The electrode body is A plurality of electrodes arranged in one direction; a separator formed in a zigzag shape and insulating each of the plurality of electrodes, The separator is a plurality of intervening portions interposed between the pair of electrodes adjacent to each other in the one direction; an upper folded portion connecting an upper end portion of one of the plurality of intervening portions to an upper end portion of another of the plurality of intervening portions that is adjacent to the one intervening portion on one side in the one direction; a lower folded portion connecting a lower end portion of one of the plurality of intervening portions to a lower end portion of another of the plurality of intervening portions that is adjacent to the one intervening portion on the other side in the one direction, At least one of the upper folded portion and the lower folded portion is provided with a discharge hole for discharging gas.

[0051] In this energy storage cell, exhaust holes are provided in at least one of the upper and lower folded portions of the separator, so that gas generated within the electrode body is effectively exhausted to the outside of the electrode body through the exhaust holes, thereby preventing gas from accumulating within the electrode body.

[0052] [Aspect 2] the separator further includes an outermost covering portion that collectively covers the upper folded portion and the lower folded portion, 2. The energy storage cell according to claim 1, wherein the discharge hole is provided in the outermost covering portion.

[0053] [Aspect 3] 3. The energy storage cell according to aspect 2, wherein the discharge hole provided in the outermost cover portion overlaps in the vertical direction with the discharge hole provided in at least one of the upper folded portion and the lower folded portion.

[0054] In this embodiment, gas is discharged more smoothly through the discharge holes provided in at least one of the upper folded portion and the lower folded portion and the discharge holes provided in the outermost covering portion.

[0055] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims rather than the above description of the embodiments, and further includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0056] 1 storage cell, 100 electrode body, 110 positive electrode, 112 positive current collecting foil, 112p positive electrode tab, 114 positive electrode active material layer, 120 negative electrode, 122 negative current collecting foil, 122n negative electrode tab, 130 separator, 132a interposing portion, 132b upper folded portion, 132c lower folded portion, 132d outermost coating portion, 200 cell case, 210 case body, 220 lid, 300 external terminal, 400 connecting member, 410 current collecting tab, 420 sub-tab, 430 connecting pin, 500 insulating member, 510 upper insulating portion, 520 lower insulating portion, 530 insulator, 540 insulating plate, H discharge hole.

Claims

1. An electrode body; a cell case that houses the electrode assembly, The electrode body is A plurality of electrodes arranged in one direction; a separator formed in a zigzag shape and insulating each of the plurality of electrodes, The separator is a plurality of intervening portions interposed between the pair of electrodes adjacent to each other in the one direction; an upper folded portion connecting an upper end portion of one of the plurality of intervening portions to an upper end portion of another of the plurality of intervening portions that is adjacent to the one intervening portion on one side in the one direction; a lower folded portion connecting a lower end portion of one of the plurality of intervening portions to a lower end portion of another of the plurality of intervening portions that is adjacent to the one intervening portion on the other side in the one direction; an outermost covering portion that covers the upper folded portion and the lower folded portion together, At least one of the upper folded portion and the lower folded portion is provided with a discharge hole for discharging gas, The discharge hole is provided in the outermost covering portion.

2. The energy storage cell according to claim 1 , wherein the discharge hole provided in the outermost covering portion overlaps in the vertical direction with the discharge hole provided in at least one of the upper folded portion and the lower folded portion.

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