Electrode body and storage cell

Abstract

To provide an electrode body and a power storage cell in which positional displacements of electrodes can be suppressed.SOLUTION: An electrode body 100 includes a plurality of electrode bodies 110, 120 arranged in one direction; and a separator 130 formed in a winding pattern for insulating a plurality of electrodes from one another. The separator 130 includes: a plurality of inclusions 132a intervening between a pair of electrodes; an upper folded part 132b; a lower folded part 132a; and the outermost coating part 132d for coating the upper folded part and the lower folded part together. The upper folded part 132b is connected to the outermost coating part and the lower folded part 132c is connected to the outermost coating unit.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Japanese Patent Application Laid-Open Publication No. 2021-48141 discloses a stacked electrode group including a plurality of alternatingly arranged positive electrodes and negative electrodes and a separator. The separator has a zigzag-shaped zigzag portion disposed between the positive and negative electrodes and a cover portion continuous with the zigzag portion. The cover portion is disposed so as to cover the periphery of the stacked electrode group. The tip of the cover portion is connected to the base of the cover portion by insulating tape or thermal welding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-48141 Summary of the Invention [Problem to be solved by the invention]

[0004] In the stacked electrode group described in Patent Publication No. 2021-48141, there is a concern that the electrodes may become misaligned when the stacked electrode group is transported, when the stacked electrode group is inserted into a cell case, or when a storage cell including the stacked electrode group is vibrated.

[0005] An object of the present disclosure is to provide an electrode assembly and a storage cell that are capable of suppressing misalignment between electrodes. [Means for solving the problem]

[0006] An electrode body according to one aspect of the present disclosure comprises a plurality of electrodes arranged in one direction, and a separator formed in a zigzag shape that 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 adjacent to the one intervening portion on one side in the one direction, 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 adjacent to the one intervening portion on the other side in the one direction, and an outermost covering portion that collectively covers the upper fold portion and the lower fold portion, wherein the upper fold portion is connected to the outermost covering portion, and the lower fold portion is connected to the outermost covering portion.

[0007] An energy storage cell according to one aspect of the present disclosure includes the electrode assembly and a cell case that houses the electrode assembly. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide an electrode assembly and a storage cell that are capable of suppressing misalignment between electrodes. [Brief explanation of the drawings]

[0009] [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 to 10C are diagrams schematically illustrating a process of forming a separator into a zigzag shape. [Figure 6] FIG. 2 is a plan view schematically illustrating a roller. [Figure 7] 10A and 10B are perspective views schematically illustrating a process of connecting an electrode tab and a current collecting tab. [Figure 8] 10A and 10B are perspective views schematically illustrating a process of bending an electrode tab and a current collecting tab. [Figure 9] FIG. 10 is a perspective view schematically showing a step of inserting the electrode body into the case body. [Figure 10] FIG. 10 is a perspective view schematically showing a modified example of the electrode body. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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.

[0011] 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.

[0012] 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.

[0013] Fig. 3 is a cross-sectional view of an electrode assembly. As shown in Fig. 3, the electrode assembly 100 includes a plurality of electrodes 110, 120, a separator 130, and an insulating film 140 (see Fig. 9).

[0014] 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.

[0015] 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 7, 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).

[0016] 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 7, 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.

[0017] 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.

[0018] 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. The separator 130 has a plurality of interposed portions 132a, a plurality of upper folded portions 132b, a plurality of lower folded portions 132c, and an outermost covering portion 132d.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The outermost covering portion 132d collectively covers each of the upper folded portions 132b and each of the lower folded portions 132c. More specifically, the outermost covering portion 132d collectively covers all of the electrodes 110, 120, all of the interposed 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.

[0023] As shown in Fig. 3, the outermost covering portion 132d includes a two-layer portion 132d1 made up of two layers. In the example shown in Fig. 3, the two-layer portion 132d1 is in contact with the lower folded portion 132c.

[0024] The outermost covering portion 132d includes an end 132e (see FIGS. 3 and 4) provided in a position that does not overlap with the positive electrode active material layer 114 and the negative electrode active material layer 124 in one direction. The end 132e is provided in a position facing the upper folded portion 132b or the lower folded portion 132c. In this embodiment, the end 132e of the outermost covering portion 132d is provided below each of the electrodes 110, 120. As shown in FIG. 3, the end 132e is provided below the lower end of the negative electrode current collector foil 122 of the negative electrode 120.

[0025] As shown in FIG. 3, the outermost covering portion 132d is connected to each of the upper folded portions 132b and each of the lower folded portions 132c. Specifically, heat is applied to the portions of the outermost covering portion 132d that overlap with each of the upper folded portions 132b from the outside by laser irradiation or the like as indicated by the arrows in FIG. 3, and heat is also applied to the portions of the outermost covering portion 132d that overlap with each of the lower folded portions 132c from the outside by laser irradiation or the like as indicated by the arrows in FIG. 3. This connects (welds) the outermost covering portion 132d to each of the upper folded portions 132b and each of the lower folded portions 132c. In particular, the two-layer portion 132d1 and the terminal end 132e are connected (welded) to the lower end of the negative current collector foil 122 of the negative electrode 120.

[0026] The outermost covering portion 132d may be connected (welded) to each of the upper folded portions 132b and each of the lower folded portions 132c by other heating means such as a hot press, or may be connected (adhered) to each of the upper folded portions 132b and each of the lower folded portions 132c by an adhesive. When an adhesive is used, the adhesive may be applied to the entire inner surface of the outermost covering portion 132d, or the adhesive may be applied in spots or lines to portions of the inner surface of the outermost covering portion 132d that face each of the upper folded portions 132b and each of the lower folded portions 132c.

[0027] The insulating film 140 covers the peripheral and bottom surfaces of the electrodes 110, 120 and the separator 130. In Fig. 9, the insulating film 140 has a dotted pattern.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] A pair of connecting members 400 (see FIG. 2) connect the multiple electrode tabs 112p, 122n to the external terminals 300. One connecting member 400 connects the multiple positive electrode tabs 112p to the positive electrode external terminals 300, and the other connecting member 400 connects the multiple 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.

[0035] The connecting member 400 includes a current collecting tab 410 , a sub-tab 420 , and a connecting pin 430 .

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] Next, the manufacturing process of the energy storage cell 1 will be described with reference to FIGS.

[0045] First, as shown in Fig. 5, the separator 130 is folded zigzag using a roller 50, with the electrodes 110, 120 alternately arranged between a pair of interposed portions 132a. As shown in Fig. 6, the roller 50 is formed in a crown shape. That is, the roller 50 is formed in a shape that increases in diameter from the end portion in the direction of the rotation axis of the roller 50 toward the central portion 52. In this way, when the separator 130 is folded zigzag, the formation of wrinkles in the central portion of the separator 130 in the width direction (the direction parallel to the rotation axis of the roller 50) is suppressed.

[0046] Then, after winding the outermost covering portion 132d of the separator 130, for example, a laser is irradiated from the outside of the outermost covering portion 132d to connect (weld) the two-layer portion 132d1 including the terminal end 132e to each lower folded portion 132c, connect (weld) each lower folded portion 132c to the lower end of each negative electrode current collector foil 122, and connect (weld) each upper folded portion 132b to the outermost covering portion 132d. At this time, it is preferable that the terminal end 132e is connected first. It is also preferable that non-contact pressure (such as dry air injection) is applied to the laser irradiated portion.

[0047] Next, as shown in Fig. 7, one end 422 of the sub-tab 420 is connected to the multiple electrode tabs 112p, 122n by welding or the like. Thereafter, as shown by the arrow in Fig. 8, one end 422 of the sub-tab 420 and the multiple electrode tabs 112p, 122n are bent so that one end 422 of the sub-tab 420 contacts the side portion 412 of the current collecting tab 410.

[0048] 9, the peripheral and bottom surfaces of the multiple electrodes 110, 120 and separator 130 are collectively covered with insulating film 140, and then the electrode body 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.

[0049] 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.

[0050] As described above, in the electrode assembly 100 of this embodiment, the relative displacement of the upper folded portion 132b and the lower folded portion 132c with respect to the outermost covering portion 132d is suppressed, and therefore, misalignment of the electrodes 110, 120 with respect to each other is suppressed.

[0051] 10, the electrode assembly 100 may further include a liquid retention member 150 capable of retaining an electrolyte. The liquid retention member 150 is a member different from the separator 130. The liquid retention member 150 is made of, for example, a porous material. The liquid retention member 150 is provided at the ends of the multiple electrodes 110, 120 and the separator 130 in the width direction. The liquid retention member 150 may also be provided at the upper or lower ends of the multiple electrodes 110, 120 and the separator 130.

[0052] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0053] [Aspect 1] 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, the upper folded portion is connected to the outermost covering portion, The electrode body, wherein the lower folded portion is connected to the outermost covering portion.

[0054] In this electrode assembly, the relative displacement of the upper folded portion and the lower folded portion with respect to the outermost covering portion is suppressed, and therefore, misalignment between the electrodes is suppressed.

[0055] [Aspect 2] the outermost covering portion includes a terminal end provided at a position opposite the upper folded portion or the lower folded portion, The electrode body of embodiment 1, wherein the termination is connected to the electrode.

[0056] In this embodiment, the connection strength at the end of the outermost coating is increased, which prevents peeling from the end. Furthermore, since the end does not overlap with the electrode in one direction, uneven surface pressure acting on the electrode due to the presence of the end is prevented.

[0057] [Aspect 3] the outermost coating portion includes a two-layer portion composed of two layers, 3. The electrode assembly according to aspect 1 or 2, wherein the two-layer portion is connected to the electrode.

[0058] In this embodiment, the positional deviation of the electrodes relative to the separator is more reliably suppressed.

[0059] [Aspect 4] The battery further includes a liquid holding member that is a member different from the separator and is capable of holding an electrolytic solution, The electrode assembly according to any one of aspects 1 to 3, wherein the liquid retention member is provided on at least one of an end of the separator in the vertical direction and an end of the separator in the width direction perpendicular to both the one direction and the vertical direction.

[0060] [Aspect 5] The electrode assembly according to any one of aspects 1 to 4; a cell case that houses the electrode assembly.

[0061] In this embodiment, the electrolyte released from the negative electrode is held in the liquid holding member, and the negative electrode absorbs the electrolyte, thereby preventing a shortage of electrolyte at the negative electrode.

[0062] 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 description of the above embodiments, and further includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0063] 1 storage cell, 100 electrode body, 110 positive electrode, 112 positive electrode current collector foil, 112p positive electrode tab, 114 positive electrode active material layer, 120 negative electrode, 122 negative electrode current collector foil, 122n negative electrode tab, 130 separator, 132a interposition portion, 132b upper folded portion, 132c lower folded portion, 132d outermost coating portion, 132d1 two-layer portion, 132e termination, 140 insulating film, 150 liquid retention member, 200 cell case, 210 case body, 220 lid, 300 external terminal, 400 connecting member, 410 current collector tab, 420 sub-tab, 430 connecting pin, 500 insulating member, 510 upper insulating portion, 520 lower insulating portion, 530 insulator, 540 Insulating plate.

Claims

1. 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, the upper folded portion is connected to the outermost covering portion, the lower folded portion is connected to the outermost covering portion, the outermost covering portion is configured with two layers and includes a two-layer portion that is in contact with the upper folded portion or the lower folded portion, The two-layer portion is connected to the electrode together with the upper folded portion or the lower folded portion.

2. the outermost covering portion includes a terminal end provided at a position opposite the upper folded portion or the lower folded portion, The electrode assembly according to claim 1 , wherein the terminal end is connected to the electrode.

3. The battery further includes a liquid holding member that is a member different from the separator and is capable of holding an electrolytic solution, 2. The electrode assembly according to claim 1, wherein the liquid retention member is provided on at least one of an end of the separator in the vertical direction and an end of the separator in a width direction perpendicular to both the one direction and the vertical direction.

4. The electrode assembly according to claim 1 ; a cell case that houses the electrode assembly.

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