Power storage cell and method of producing electrode assembly

Abstract

To provide a power storage cell in which permeation of an electrolytic solution in an electrode assembly is less likely to become uneven.SOLUTION: An electrode assembly 100 includes a plurality of positive electrodes, a plurality of negative electrodes, and a separator. The electrode assembly has a shape longer in a width direction than in a thickness direction. The electrode assembly includes an upper portion 11, a bottom portion 12, a first end portion 13 located at one end in the width direction, and a second end portion 14 located at the other end in the width direction. Each of the plurality of positive electrodes includes a positive electrode tab 112p protruding from the first end portion, and each of the plurality of negative electrodes includes a negative electrode tab 122n protruding from the second end portion. A first welding portion 15 is formed at a portion located below the positive electrode tab, and a second welding portion 16 is formed at a portion located below the negative electrode tab. A third welding portion 17 in contact with the first welding portion and a fourth welding portion 18 in contact with the second welding portion are formed in the bottom portion. The third welding portion and the fourth welding portion are disposed at an interval with a central portion of the bottom portion being interposed therebetween.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing an electric storage cell and an electrode assembly. [Background technology]

[0002] Patent Document 1 (JP 2009-88279 A) discloses a method for bonding electrodes and separators, or separators themselves, in an electrode assembly in which electrodes containing a binder are stacked with a separator interposed therebetween, with an adhesive mainly composed of the same type of component as the binder of the electrodes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-88279 A Summary of the Invention [Problem to be solved by the invention]

[0004] The electrode body expands and contracts repeatedly as it is repeatedly charged and discharged. At that time, the electrolyte enters and exits from the periphery of the electrode body. In an electrode body formed horizontally, the electrolyte is maintained in the peripheral portion as the electrolyte enters and exits from the periphery of the electrode body. On the other hand, the electrolyte is easily depleted inside the electrode body, especially in the center, over time. As a result, the electrolyte may not penetrate uniformly inside the electrode body.

[0005] An object of the present disclosure is to provide an electricity storage cell in which the electrolyte is less likely to permeate non-uniformly inside the electrode assembly. [Means for solving the problem]

[0006] [1] A battery comprising an electrode assembly, a cell case for accommodating the electrode assembly, and an electrolyte solution accommodated in the cell case; the electrode body includes a plurality of positive electrodes and a plurality of negative electrodes arranged in a thickness direction, and a separator for insulating each of the positive electrodes and each of the negative electrodes; The electrode body has a shape that is longer in a width direction perpendicular to both the thickness direction and the vertical direction than in the thickness direction, The electrode body includes an upper portion, a bottom portion, a first end portion located at one end in the width direction, and a second end portion located at the other end in the width direction, the plurality of positive electrodes includes a positive electrode tab protruding from the first end, the plurality of negative electrodes include a negative electrode tab protruding from the second end, a first welded portion is formed in a portion of the first end portion that is located below the positive electrode tab, a second welded portion is formed in a portion of the second end portion that is located below the negative electrode tab, a third welded portion in contact with the first welded portion and a fourth welded portion in contact with the second welded portion are formed on the bottom portion, The third welded portion and the fourth welded portion are arranged at a distance from each other with a central portion of the bottom portion therebetween.

[0007] The electrode body expands and contracts when it is charged and discharged. The expansion and contraction of the electrode body causes the electrolyte to enter and exit the electrode body. On the other hand, in the welded portion, the micropores of the separator are closed, and the electrolyte cannot pass through. Therefore, by forming welded portions at the lower portions of both ends of the electrode body in the width direction and at both ends of the bottom of the electrode body in the width direction, the electrolyte is blocked from entering and exiting the welded portion, and the electrolyte can be maintained in a state in which it has soaked into the corners of the bottom of the electrode body. Therefore, the electrolyte is less likely to soak unevenly inside the electrode body.

[0008] Fig. 1 is a schematic diagram showing the degree of electrolyte penetration in an electrode body in which no welded portion is formed. In Fig. 1, the left-right direction indicates the horizontal length of the electrode body, and the up-down direction indicates the up-down direction of the electrode body. As described above, it is considered that the electrolyte that has soaked into the corners of the bottom of the electrode body permeates over time into the region Z in the center of Fig. 1, where the electrolyte has difficulty permeating, thereby suppressing the variation in the degree of electrolyte penetration.

[0009] [2] The storage cell according to [1], wherein the height of the first welded portion and the height of the second welded portion are greater than or equal to one-third and less than or equal to one-half of the height of the electrode body.

[0010] [3] The storage cell according to [1] or [2], wherein the width direction length of the third welded portion and the width direction length of the fourth welded portion are greater than or equal to one-quarter and less than or equal to one-third of the width direction length of the electrode body.

[0011] [4] A method for manufacturing an electrode assembly in which a positive electrode and a negative electrode are arranged side by side with a separator therebetween, comprising the steps of: providing the separator; disposing the positive electrode on the separator; a step of folding back the separator to form a folded portion for positioning the positive electrode relative to the separator, and disposing the separator on the positive electrode; fusing the separator to the positive electrode by heating the separator; disposing the negative electrode on the separator welded onto the positive electrode; a step of folding back the separator to form a folded portion for positioning the negative electrode relative to the separator, and disposing the separator on the negative electrode; and heating the separator to fuse the separator to the negative electrode. Effect of the Invention

[0012] According to the present disclosure, it is possible to provide an electricity storage cell in which the electrolyte is less likely to permeate non-uniformly inside the electrode assembly. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing the degree of permeation of an electrolyte into an electrode assembly in which no welded portion is formed. [Diagram 2] FIG. 2 is an example of a perspective view that illustrates a schematic view of the electricity storage cell according to the first embodiment. [Diagram 3] FIG. 3 is a cross-sectional view of the power storage cell shown in FIG. [Figure 4] 4(a) and (b) are examples of perspective views that diagrammatically show the electrode assembly in the first embodiment. [Diagram 5] FIG. 5 is a diagram illustrating an electrode assembly according to the second embodiment. [Figure 6] FIG. 6 is a diagram illustrating a manufacturing method of the electrode assembly in the second embodiment. [Figure 7] FIG. 7 is a diagram illustrating a manufacturing method of the electrode assembly in the second embodiment. [Figure 8] FIG. 8 is a diagram illustrating a manufacturing method of the electrode assembly in the second embodiment. [Figure 9] FIG. 9 is a diagram illustrating a manufacturing method of the electrode assembly in the second embodiment. [Figure 10] FIG. 10 is a diagram illustrating an electrode assembly according to the third embodiment. [Figure 11] FIG. 11 is a diagram illustrating a manufacturing method of the electrode assembly in the third embodiment. [Figure 12] FIG. 12 is a diagram illustrating a manufacturing method of the electrode assembly in the third embodiment. [Figure 13] FIG. 13 is a diagram illustrating a manufacturing method of the electrode assembly in the third embodiment. [Figure 14] FIG. 14 is a diagram illustrating a manufacturing method of the electrode assembly in the third embodiment. [Figure 15]FIG. 15 is a diagram illustrating a manufacturing method of the electrode assembly in the third embodiment. [Figure 16] FIG. 16 is a diagram illustrating a manufacturing method of the electrode assembly in the third embodiment. [Figure 17] FIG. 17 is a diagram illustrating an electrode assembly according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Embodiment 1> The energy storage cell according to the present embodiment will be described with reference to the drawings. In the drawings referred to below, the same or corresponding components are denoted by the same reference numerals.

[0015] Fig. 2 is an example of a perspective view that shows a schematic diagram of a storage cell in this embodiment. Fig. 3 is a cross-sectional view of the storage cell shown in Fig. 2. Figs. 4(a) and (b) are examples of perspective views that show a schematic diagram of an electrode assembly in this embodiment.

[0016] As shown in FIGS. 2 and 3, the energy storage cell 1 includes an electrode assembly 100, a cell case 200, a pair of external terminals 300, a pair of connecting members 400, an insulating member 500, and an electrolyte (not shown).

[0017] The electrode body 100 includes a plurality of positive electrodes 110 and a plurality of negative electrodes 120 arranged side by side in the thickness direction (T in FIG. 2), and a separator 130 for insulating each of the positive electrodes 110 and each of the negative electrodes 120. The electrode body 100 is formed in a rectangular shape that is longer in a direction (W in FIG. 2) perpendicular to both the thickness direction and the up-down direction (H in FIG. 2) than in the thickness direction. The electrode body 100 includes an upper portion 11, a bottom portion 12, a first end portion 13 located at one end in the width direction, and a second end portion 14 located at the other end in the width direction.

[0018] Each positive electrode 110 is formed in a rectangular shape that is long in the width direction. Each positive electrode 110 has a positive electrode current collector foil and a positive electrode active material layer provided on both sides of the positive electrode current collector foil. The positive electrode 110, specifically the positive electrode current collector foil, includes a positive electrode tab 112p that protrudes from the first end 13 toward one side in the width direction. The positive electrode tab 112p is not provided with a positive electrode active material layer.

[0019] 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 and a negative electrode active material layer provided on both sides of the negative electrode current collector foil. The negative electrode 120, specifically the negative electrode current collector foil, includes a negative electrode tab 122n that protrudes from the second end 14 toward one side in the width direction. The negative electrode tab 122n is not provided with a negative electrode active material layer.

[0020] At the first end 13, a first welded portion 15 is formed at a portion located below the positive electrode tab 112p. At the second end 14, a second welded portion 16 is formed at a portion located below the negative electrode tab 122n. At the bottom 12, a third welded portion 17 in contact with the first welded portion 15 and a fourth welded portion 18 in contact with the second welded portion 16 are formed. With this configuration, it is possible to block the inflow and outflow of the electrolyte at the first welded portion 15, the second welded portion 16, the third welded portion 17, and the fourth welded portion 18. As a result, it is possible to maintain a state in which the electrolyte is permeated into the corners of the bottom 12 (near the contact between the first welded portion 15 and the third welded portion 17 and near the contact between the second welded portion 16 and the fourth welded portion 18). Therefore, the electrolyte is less likely to permeate unevenly inside the electrode body 100.

[0021] The first welded portion 15, the second welded portion 16, the third welded portion 17, and the fourth welded portion 18 may be made of, for example, a resin. The first welded portion 15, the second welded portion 16, the third welded portion 17, and the fourth welded portion 18 may be made of the same resin or different resins.

[0022] It is preferable that the height H1 of the first welded portion 15 and the height H2 of the second welded portion 16 are each between one-third and one-half of the height of the electrode body 100. By setting the heights in this manner, it is expected that the electrolyte will penetrate more uniformly.

[0023] The third welded portion 17 and the fourth welded portion 18 are disposed at a distance from each other, sandwiching the central portion of the bottom portion 12. If welded portions were formed over the entire bottom portion 12, the electrolyte would not be able to flow in or out of the bottom portion 12.

[0024] It is preferable that the widthwise length W1 of the third welded portion 17 and the widthwise length W2 of the fourth welded portion 18 are each between one-quarter and one-third of the widthwise length of the electrode body 100. By setting them to such lengths, it is expected that the electrolyte will penetrate more uniformly.

[0025] 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 the permeation of ions.

[0026] The cell case 200 houses the electrode assembly 100. An electrolyte (not shown) is housed in the cell case 200. The cell case 200 is sealed. The cell case 200 has a case body 210 and a lid 220.

[0027] 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. 3, 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 up from the bottom wall 212. The peripheral wall 214 is formed in a rectangular tube 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.

[0028] 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.

[0029] The pressure release valve 222 is formed in the center of the lid 220. The pressure release valve 222 is formed to break when the internal pressure of the cell case 200 reaches or exceeds a predetermined pressure. When the pressure release valve 222 breaks, gas within the cell case 200 is released to the outside of the cell case 200 through the pressure release valve 222, and the internal pressure of the cell case 200 decreases.

[0030] 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 in 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.

[0031] A pair of external terminals 300 are fixed on the cell case 200. One of the pair of external terminals 300 is a positive external terminal, and the other is a negative external terminal. Each external terminal 300 is fixed to the upper surface of the lid 220 via an upper insulating part 510 described later. Each external terminal 300 is made of a metal such as aluminum. Each external terminal 300 is formed, for example, in a rectangular parallelepiped shape. A bus bar (not shown) is connected to each external terminal 300 by welding or the like.

[0032] The pair of connecting members 400 connect the multiple electrode tabs 112p, 122n to the external terminal 300. One connecting member 400 connects the multiple positive electrode tabs 112p to the positive electrode external terminal 300, and the other connecting member 400 connects the multiple negative electrode tabs 122n to the negative electrode external terminal 300. Since each of the pair of connecting members 400 has substantially the same structure as each other, one connecting member 400 will be described below.

[0033] The connecting member 400 has a current collecting tab 410 , a sub-tab 420 , and a connecting pin 430 .

[0034] 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.

[0035] The sub-tab 420 connects the positive electrode tabs 112p to the current collecting tab 410. One end 422 of the sub-tab 420 is connected to the positive electrode tabs 112p by welding or the like, and the other end 424 of the sub-tab 420 is connected to the side portion 412 of the current collecting tab 410 by welding or the like.

[0036] 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.

[0037] 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.

[0038] 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 is provided with an insertion hole through which the connecting pin 430 is inserted.

[0039] Lower insulating part 520 is fixed to the lower surface of lid 220. Lower insulating part 520 is disposed between lid 220 and upper part 414 and a lower part of connecting pin 430. Lower insulating part 520 is provided with an insertion hole through which connecting pin 430 is inserted.

[0040] 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.

[0041] 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 at a portion located below the pressure release valve 222 and at a portion located below the liquid injection port h.

[0042] As described above, in the energy storage cell 1 of this embodiment, the first welded portion 15 and the second welded portion 16 are formed below the first end portion 13 and the second end portion 14 located at both ends in the width direction of the electrode body 100, respectively. In addition, the third welded portion 17 and the fourth welded portion 18 are formed at both ends of the bottom portion 12 of the electrode body 100, respectively. With this configuration, it is possible to block the inflow and outflow of the electrolyte at the first welded portion 15, the second welded portion 16, the third welded portion 17, and the fourth welded portion 18, making it difficult for the electrolyte to seep into the inside of the electrode body 100 to become uneven.

[0043] <Embodiment 2> In this embodiment, an electrode assembly and a manufacturing method for the electrode assembly that can be used in the embodiment 1 will be described with reference to the drawings. Note that duplicated descriptions of the same contents as those in the embodiment 1 will be omitted.

[0044] FIG. 5 is a diagram showing an outline of the electrode assembly in this embodiment. The electrode assembly 100 in this embodiment includes a plurality of positive electrodes 110 and a plurality of negative electrodes 120 arranged in a line in the thickness direction, and a separator 130 formed in a zigzag shape for insulating the positive electrodes 110 and the negative electrodes 120. The electrode assembly 100 has a shape longer in the width direction perpendicular to both the thickness direction and the up-down direction than in the thickness direction, and includes an upper portion 11, a bottom portion 12, a first end portion 13 located at one end in the width direction, and a second end portion 14 located at the other end in the width direction. The positive electrodes 110 include a positive electrode tab 112p protruding from the first end portion 13, and the negative electrodes 120 include a negative electrode tab 122n protruding from the second end portion 14. The separator 130 has a first folded portion 131 and a second folded portion 132. The first folded portion 131 is formed at the first end portion 13. The second folded portion 132 is formed at the second end portion 14. The first folded portion 131 is welded to the positive electrode 110. The second folded portion 132 is welded to the negative electrode 120.

[0045] The separator 130 of the electrode body 100 in this embodiment is formed in a zigzag shape between each of the positive electrodes 110 and each of the negative electrodes 120, and is welded to the end of the positive electrode 110 and the end of the negative electrode 120. In this manner, it is possible to prevent the positive electrode 110 and the negative electrode 120 from being misaligned with respect to the separator 130.

[0046] Next, a manufacturing process for the electrode assembly 100 will be described. The manufacturing method for the electrode assembly 100 in this embodiment is a manufacturing method for the electrode assembly 100 in which the positive electrode 110 and the negative electrode 120 are arranged side by side with the separator 130 interposed therebetween, and includes a step of preparing the separator 130 (a preparation step), a step of arranging the positive electrode 110 on the separator 130 (a positive electrode arrangement step), and a step of folding back the separator 130 to form a first folded portion 131 that positions the positive electrode 110 relative to the separator 130 and arrange the separator 130 on the positive electrode 110 (a step of folding back the separator 130). The method includes a step of folding back the separator 130, a step of arranging the negative electrode 120 on the separator 130 arranged on the positive electrode 110 (a negative electrode arrangement step), a step of folding back the separator 130 to form a second fold portion 132 that positions the negative electrode 120 relative to the separator 130 and arranges the separator 130 on the negative electrode 120 (a second folding step), and a step of heating the first fold portion 131 and the second fold portion 132 to weld them to the positive electrode 110 and the negative electrode 120 (a welding step).

[0047] In the preparation step, a long separator 130 is prepared.

[0048] In the positive electrode arranging step, the positive electrode 110 is arranged on the separator 130. Note that Fig. 6 shows the state after the positive electrode arranging step.

[0049] In the first folding step, the separator 130 is folded back so that the separator 130 is disposed on the positive electrode 110. As a result, a first folded portion 131 is formed on the separator 130. The first folded portion 131 determines the position of the positive electrode 110 relative to the separator 130. That is, in this step, the separator 130 is folded back to form the first folded portion 131 that determines the position of the positive electrode 110 relative to the separator 130, and the separator 130 is disposed on the positive electrode 110. Note that FIG. 7 shows the state after the first folding step.

[0050] In the negative electrode arrangement step, the negative electrode 120 is arranged on the separator 130 that is arranged on the positive electrode 110. Note that Fig. 8 shows the state after the negative electrode arrangement step.

[0051] In the second folding step, similarly to the first folding step, the separator 130 is folded back to form a second folded portion 132 for positioning the negative electrode 120 relative to the separator 130, and the separator 130 is placed on the negative electrode 120. Note that Fig. 9 shows the state after the second folding step.

[0052] Thereafter, the positive electrode arrangement step, the first folding step, the negative electrode arrangement step, and the second folding step are repeated in this order.

[0053] In the welding step, the first folded portion 131 and the second folded portion 132 are heated to weld them to the positive electrode 110 and the negative electrode 120. There are no particular limitations on the heating method, and examples of the heating method include a heater.

[0054] In the welding process, it is preferable to further heat at least one selected from the group consisting of the upper portion 11 and the bottom portion 12 to weld the separator 130 to the positive electrode 110 and the negative electrode 120. The electrode body 100 is mounted, for example, on a vehicle. When mounted on a vehicle, vibrations are often applied in the vertical direction. Therefore, by heating at least one selected from the group consisting of the upper portion 11 and the bottom portion 12 in the vertical direction of the electrode body 100, the positional deviation of the positive electrode 110 and the negative electrode 120 relative to the separator 130 is further suppressed. In the welding process, it is more preferable to heat the upper portion 11 and the bottom portion 12 to weld them to the positive electrode 110 and the negative electrode 120.

[0055] The upper portion 11 and the bottom portion 12 may be heated entirely or only partially, but it is preferable that the upper portion 11 and the bottom portion 12 are heated entirely.

[0056] As described above, in the electrode body 100 and its manufacturing method of the present embodiment, the first folded portion 131 and the second folded portion 132 of the separator 130 are heated and welded to each other, thereby positioning the positive electrode 110 and the negative electrode 120 relative to the separator 130, thereby suppressing misalignment of the positive electrode 110 and the negative electrode 120 relative to the separator 130.

[0057] <Embodiment 3> In this embodiment, an electrode assembly and a method for manufacturing the electrode assembly that can be used in embodiment 1 will be described with reference to the drawings. Note that duplicated descriptions of the same contents as in embodiments 1 and 2 will be omitted.

[0058] 10 is a schematic diagram of an electrode assembly according to the present embodiment. The electrode assembly 100 according to the present embodiment has the same structure as that of the second embodiment.

[0059] The manufacturing method of the electrode assembly 100 in this embodiment is partially different from that in embodiment 2. The manufacturing method of the electrode assembly 100 in this embodiment is a manufacturing method of the electrode assembly 100 in which the positive electrode 110 and the negative electrode 120 are arranged side by side with the separator 130 interposed therebetween, and includes a step of preparing the separator 130 (preparation step), a step of arranging the positive electrode 110 on the separator 130 (positive electrode arrangement step), a step of folding back the separator 130 to form a folded portion 131 for positioning the positive electrode 110 relative to the separator 130, and a step of arranging the separator 130 on the positive electrode 110 (first folding step), The method includes a step of heating the first folded portion 131 to weld it to the positive electrode 110 (first welding step), a step of arranging the negative electrode 120 on the separator 130 arranged on the positive electrode 110 (negative electrode arrangement step), a step of folding back the separator 130 to form a folded portion 132 that positions the negative electrode 120 relative to the separator 130 and arranges the separator 130 on the negative electrode 120 (second folding step), and a step of heating the second folded portion 132 to weld it to the negative electrode 120 (second welding step).

[0060] The manufacturing method of the electrode body 100 in this embodiment differs from that in the second embodiment in that it has a first welding step and a second welding step. The first welding step and the second welding step will be described below. Note that Fig. 11 shows the state after the positive electrode arrangement step, Fig. 12 shows the state after the first folding step, Fig. 14 shows the state after the negative electrode arrangement step, and Fig. 15 shows the state after the second folding step.

[0061] In the first welding step, the first folded portion 131 is heated and welded to the positive electrode 110. Note that Fig. 13 shows the state after the first welding step.

[0062] In the second welding step, the second folded portion 132 is heated and welded to the negative electrode 120. Note that Fig. 16 shows the state after the second welding step.

[0063] In this embodiment, the positive electrode arranging step, the first folding step, the first welding step, the negative electrode arranging step, the second folding step, and the second welding step are repeated in this order.

[0064] In this embodiment, a third welding step may be included in which at least one selected from the group consisting of the upper portion 11 and the bottom portion 12 is heated to weld the separator 130 to the positive electrode 110 and the negative electrode 120. In the third welding step, it is preferable to heat the upper portion 11 and the bottom portion 12 to weld them to the positive electrode 110 and the negative electrode 120.

[0065] Top 11 and bottom 12 may be heated simultaneously with heating first folded portion 131 and second folded portion 132 in the first and second welding steps to weld separator 130 to positive electrode 110 and negative electrode 120. That is, in the case shown in Figures 13 and 16, first folded portion 131 and second folded portion 132 may be heated simultaneously with heating top and bottom portions sequentially in the electrode body formation process to weld separator 130 to positive electrode 110 and negative electrode 120.

[0066] As described above, in the electrode body 100 and its manufacturing method of the present embodiment, the first folded portion 131 and the second folded portion 132 of the separator 130 are heated and welded to each other, thereby positioning the positive electrode 110 and the negative electrode 120 relative to the separator 130, thereby suppressing misalignment of the positive electrode 110 and the negative electrode 120 relative to the separator 130.

[0067] <Embodiment 4> In this embodiment, an electrode assembly and a manufacturing method for the electrode assembly that can be used in embodiment 1 will be described with reference to the drawings. Note that duplicated descriptions of the same contents as in embodiments 1 to 3 will be omitted.

[0068] 17 is a diagram showing an outline of the electrode assembly in this embodiment. The electrode assembly 100 in this embodiment includes a plurality of positive electrodes 110 and a plurality of negative electrodes 120 arranged in a line in the thickness direction, a separator 130 formed in a zigzag shape for insulating each of the positive electrodes 110 and each of the negative electrodes 120, and has a shape longer in the width direction perpendicular to both the thickness direction and the up-down direction than in the thickness direction, and includes an upper portion 11, a bottom portion 12, a first end portion 13 located at one end in the width direction, and a second end portion 14 located at the other end in the width direction, and the plurality of positive electrodes 110 include a positive electrode tab 112p protruding from the first end portion 13, and the plurality of negative electrodes 120 include a negative electrode tab 122n protruding from the second end portion 14. The separator 130 includes a first outer separator 133, a second outer separator 134, an inner separator 135, a first outer folded portion 136, and a second outer folded portion 137. The first outer folded portion 136 connects the first outer separator 133 and the inner separator 135. The second outer folded portion 137 connects the second outer separator 134 and the inner separator 135. The inner separator 135 has a first folded portion 131 and a second folded portion 132. The first folded portion 131, the first outer folded portion 136, and the second outer folded portion 137 are formed at the first end portion 13. The second folded portion 132 is formed at the second end portion 14. The first outer folded portion 136 and the second outer folded portion 137 have a chamfered shape.

[0069] As shown in Fig. 17, the separator 130 of the electrode assembly 100 in this embodiment includes a first external separator 133 and a second external separator 134 arranged at the outermost part in the thickness direction of the electrode assembly 100, an internal separator 135 arranged inside, a first external folded portion 136 connecting the first external separator 133 and the internal separator 135, and a second external folded portion 137 connecting the second external separator 134 and the internal separator 135. The first external folded portion 136 and the second external folded portion 137 have a chamfered shape. In the electrode assembly 100 having such a shape, the electrode assembly 100 can be smoothly inserted into the cell case by inserting the electrode assembly 100 into the cell case from the first end 13 having the chamfered shape. Separator 130 is configured by connecting first outer separator 133, first outer folded portion 136, inner separator 135, second outer folded portion 137, and second outer separator 134 together.

[0070] The chamfered shape is not particularly limited, and may be an angled flat surface (rounded flat surface) rather than a sharp corner.

[0071] The manufacturing method of the electrode assembly 100 in this embodiment is a manufacturing method of the electrode assembly 100 in which the positive electrode 110 and the negative electrode 120 are arranged side by side with the separator 130 interposed therebetween, and includes a step of preparing the separator 130 (preparation step), a step of arranging the positive electrode 110 on the separator 130 (first positive electrode arrangement step), a step of folding back the separator 130 to form a first outer fold portion 136 that positions the positive electrode 110 relative to the separator 130 and arranging the separator 130 on the positive electrode 110 (first outer folding step), a step of arranging the negative electrode 120 on the separator 130 arranged on the positive electrode 110 (negative electrode arrangement step), and a step of folding back the separator 130. the first external fold portion 136 and the second external fold portion 137 are folded back to form a second external fold portion 137 that positions the positive electrode 110 relative to the separator 130, and the separator 130 is placed on the positive electrode 110 (second external folding process); and the first external fold portion 136 and the second external fold portion 137 are folded back to form a chamfered shape (chamfering process).

[0072] The manufacturing method of the electrode body 100 in this embodiment includes a chamfering step. The chamfering step will be described below.

[0073] In the chamfering process, the first external folded portion 136 and the second external folded portion 137 are heated to form a chamfered shape. The chamfered shape is formed by heating, that is, the separator is hardened by heating. This prevents damage to portions of the electrode body 100 other than the chamfered portion even if the cell case and the chamfered portion of the electrode body 100 come into contact with each other when the electrode body 100 is inserted into the cell case.

[0074] As described above, in the electrode body 100 and its manufacturing method in this embodiment, the first external folded portion 136 and the second external folded portion 137 are provided at the first end 13 of the first external separator 133 and the second external separator 134 arranged at the outermost part in the thickness direction of the electrode body 100, and the first external folded portion 136 and the second external folded portion 137 form a chamfered shape. In the electrode body 100 having such a shape, by inserting the electrode body 100 into the cell case from the first end 13 having the chamfered shape, it is possible to achieve smooth insertion of the electrode body 100 into the cell case. In addition, since the chamfered shape is formed by heating, even if the cell case and the chamfered shape portion of the electrode body 100 come into contact when the electrode body 100 is inserted into the cell case, damage to the parts of the electrode body 100 other than the chamfered shape portion is suppressed.

[0075] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present disclosure is indicated by the claims, not by the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0076] 1 storage cell, 11 upper part, 12 bottom part, 13 first end part, 14 second end part, 15 first welded part, 16 second welded part, 17 third welded part, 18 fourth welded part, 100 electrode body, 110 positive electrode, 112p positive electrode tab, 120 negative electrode, 122n negative electrode tab, 130 separator, 131 first folded part, 132 second folded part, 133 first external separator, 134 second external separator, 135 internal separator, 136 first external folded part, 137 second external folded part, 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 part, 520 lower insulating part, 530 insulator, 540 insulating plate, H1 height of first welded part, H2 height of second welded part, W1 length of third welded part, W2 length of fourth welded part.

Claims

1. An electrode assembly, a cell case for accommodating the electrode assembly, and an electrolyte solution accommodated in the cell case; the electrode body includes a plurality of positive electrodes and a plurality of negative electrodes arranged in a thickness direction, and a separator for insulating each of the positive electrodes and each of the negative electrodes; The electrode body has a shape that is longer in a width direction perpendicular to both the thickness direction and the vertical direction than in the thickness direction, The electrode body includes an upper portion, a bottom portion, a first end portion located at one end in the width direction, and a second end portion located at the other end in the width direction, the plurality of positive electrodes includes a positive electrode tab protruding from the first end, the plurality of negative electrodes include a negative electrode tab protruding from the second end, a first welded portion is formed in a portion of the first end portion that is located below the positive electrode tab, a second welded portion is formed in a portion of the second end portion that is located below the negative electrode tab, a third welded portion in contact with the first welded portion and a fourth welded portion in contact with the second welded portion are formed on the bottom portion, The third welded portion and the fourth welded portion are arranged at a distance from each other with a central portion of the bottom portion therebetween.

2. The energy storage cell according to claim 1 , wherein a height of the first welded portion and a height of the second welded portion are each equal to or greater than one-third and equal to or less than one-half of a height of the electrode body.

3. 3 . The storage cell according to claim 1 , wherein the width direction length of the third welded portion and the width direction length of the fourth welded portion are each equal to or greater than one-quarter and equal to or less than one-third of the width direction length of the electrode body.

4. A method for manufacturing an electrode assembly in which a positive electrode and a negative electrode are arranged side by side with a separator therebetween, comprising the steps of: providing the separator; disposing the positive electrode on the separator; a step of folding back the separator to form a folded portion for positioning the positive electrode relative to the separator, and disposing the separator on the positive electrode; fusing the separator to the positive electrode by heating the separator; disposing the negative electrode on the separator welded onto the positive electrode; a step of folding back the separator to form a folded portion for positioning the negative electrode relative to the separator, and disposing the separator on the negative electrode; and heating the separator to fuse the separator to the negative electrode.

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