Method for manufacturing storage cell and 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, using an adhesive whose main component is the same type as the binder of the electrodes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-88279 Summary of the Invention [Problem to be solved by the invention]

[0004] The electrode assembly expands and contracts repeatedly as it is repeatedly charged and discharged. During this process, the electrolyte enters and exits the periphery of the electrode assembly. In a horizontally elongated electrode assembly, the electrolyte remains permeated in the peripheral areas due to the inflow and outflow of the electrolyte from the periphery. However, over time, the electrolyte tends to become depleted inside the electrode assembly, particularly in the center. As a result, the electrolyte may not penetrate uniformly inside the electrode assembly.

[0005] An object of the present disclosure is to provide an electricity storage cell in which the electrolyte solution is less likely to permeate unevenly 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 separators for insulating the positive electrodes and the negative electrodes from each other; 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 a top 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 include positive electrode tabs protruding from the first end; the plurality of negative electrodes include negative electrode tabs 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 sandwiched therebetween.

[0007] The electrode body expands and contracts during charging and discharging. This expansion and contraction of the electrode body allows the electrolyte to enter and exit the electrode body. Meanwhile, the micropores of the separator are closed at the welded portions, preventing the electrolyte from passing through. Therefore, by forming welded portions at the lower portions of both widthwise ends of the electrode body and at both widthwise ends of the bottom of the electrode body, the inflow and outflow of the electrolyte at the welded portions is blocked, allowing the electrolyte to remain permeated into the corners of the bottom of the electrode body. This reduces the likelihood of uneven permeation of the electrolyte inside the electrode body.

[0008] Figure 1 is a schematic diagram showing the degree of electrolyte penetration in an electrode body without a welded portion. In Figure 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 believed that the electrolyte that has soaked into the corners of the bottom of the electrode body gradually seeps into region Z in the center of Figure 1, where electrolyte penetration is difficult, over time, thereby suppressing 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 equal to or greater than one-third and equal to or less than one-half of the height of the electrode assembly.

[0010] [3] The storage cell according to [1] or [2], wherein the widthwise length of the third welded portion and the widthwise length of the fourth welded portion are greater than or equal to one-quarter and less than or equal to one-third of the widthwise 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 interposed therebetween, comprising: providing the separator; disposing the positive electrode on the separator; a step of folding 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 the separator to form a folded portion for positioning the negative electrode relative to the separator, and placing the separator on the negative electrode; and heating the separator to weld the separator to the negative electrode. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide an energy storage cell in which the electrolyte solution is less likely to permeate unevenly inside the electrode assembly. [Brief explanation of the drawings]

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

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

[0015] Fig. 2 is an example of a perspective view schematically showing 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 schematically showing 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 assembly 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 assembly 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 assembly 100 includes a top 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 positive electrode active material layers 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 negative electrode active material layers 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] A first welded portion 15 is formed in a portion of the first end portion 13 located below the positive electrode tab 112p. A second welded portion 16 is formed in a portion of the second end portion 14 located below the negative electrode tab 122n. 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 in the bottom portion 12. This configuration can 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, the corners of the bottom portion 12 (near the contact points between the first welded portion 15 and the third welded portion 17 and the contact points between the second welded portion 16 and the fourth welded portion 18) can be maintained in a state in which the electrolyte is permeated. This makes it less likely that the electrolyte will permeate unevenly inside the electrode body 100.

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

[0022] The height H1 of the first welded portion 15 and the height H2 of the second welded portion 16 are each preferably 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 arranged 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] The widthwise length W1 of the third welded portion 17 and the widthwise length W2 of the fourth welded portion 18 are each preferably between one-fourth and one-third of the widthwise length of the electrode body 100. By setting these 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 ions to pass through.

[0026] 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.

[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 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.

[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] 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.

[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 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.

[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 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.

[0032] 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.

[0033] The connecting member 400 includes 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 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.

[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 has 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 the upper part 414 and the lower part of connecting pin 430. Lower insulating part 520 has 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 in a portion located below the pressure release valve 222 and 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, which are located at both ends in the width direction of the electrode assembly 100. 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 assembly 100. With this configuration, it is possible to block the entry and exit 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 less likely that the electrolyte will seep into the electrode assembly 100 unevenly.

[0043] <Embodiment 2> 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 embodiment 1 will be omitted.

[0044] FIG. 5 is a schematic diagram illustrating an electrode assembly according to this embodiment. The electrode assembly 100 according to this embodiment includes a plurality of positive electrodes 110 and a plurality of negative electrodes 120 arranged in a thickness direction, and a zigzag-folded separator 130 for insulating the positive electrodes 110 and the negative electrodes 120. The electrode assembly 100 is longer in a width direction perpendicular to both the thickness direction and the vertical direction than in a thickness direction. The electrode assembly 100 includes a top 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 positive electrode tabs 112p protruding from the first end portion 13, and the negative electrodes 120 include negative electrode tabs 122n protruding from the second end portion 14. The separator 130 includes 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 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 assembly 100 in this embodiment is formed in a zigzag shape between each positive electrode 110 and each negative electrode 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 shifting in position relative 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 (preparation step), a step of arranging the positive electrode 110 on the separator 130 (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 arranging the separator 130 on the positive electrode 110 ( The method includes a step of placing the negative electrode 120 on the separator 130 placed on the positive electrode 110 (a first folding step), a step of placing the negative electrode 120 on the separator 130 placed on the positive electrode 110 (a negative electrode placing step), a step of folding back the separator 130 to form a second folding portion 132 that positions the negative electrode 120 relative to the separator 130 and placing the separator 130 on the negative electrode 120 (a second folding step), and a step of heating the first folding portion 131 and the second folding 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. This forms a first folded portion 131 on the separator 130. The first folded portion 131 positions 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 positions the positive electrode 110 relative to the separator 130, and also to dispose the separator 130 on the positive electrode 110. Note that FIG. 7 shows the state after the first folding step.

[0050] In the negative electrode arranging 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 arranging step.

[0051] In the second folding step, similar to the first folding step, the separator 130 is folded back to form a second folded portion 132 that positions 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 include using a heater.

[0054] In the welding step, it is preferable to further heat at least one selected from the group consisting of the top portion 11 and the bottom portion 12 to weld the separator 130 to the positive electrode 110 and the negative electrode 120. The electrode assembly 100 is mounted, for example, in a vehicle. When mounted in a vehicle, vibrations are often applied in the vertical direction. Therefore, by heating at least one selected from the group consisting of the top portion 11 and the bottom portion 12 of the electrode assembly 100, which are in the vertical direction, misalignment of the positive electrode 110 and the negative electrode 120 with respect to the separator 130 is further suppressed. In the welding step, it is more preferable to heat the top 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 this 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 diagram schematically showing an electrode assembly according to this embodiment. The electrode assembly 100 according to this 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), and a step of folding back the separator 130 to form a folded portion 131 that positions the positive electrode 110 relative to the separator 130, and 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 that is 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 assembly 100 in this embodiment differs from that in Embodiment 2 in that it includes 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] This embodiment may include a third welding step of heating at least one selected from the group consisting of the top portion 11 and the bottom portion 12 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 top portion 11 and the bottom portion 12 to weld them to the positive electrode 110 and the negative electrode 120.

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

[0066] As described above, in the electrode body 100 and its manufacturing method of this 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 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 to 3 will be omitted.

[0068] 17 is a diagram illustrating a schematic view of an electrode assembly according to the present embodiment. The electrode assembly 100 according to the present embodiment includes a plurality of positive electrodes 110 and a plurality of negative electrodes 120 arranged in a thickness direction, and a zigzag-shaped separator 130 for insulating the positive electrodes 110 and the negative electrodes 120. The electrode assembly 100 is longer in a width direction perpendicular to both the thickness direction and the vertical direction than in the thickness direction, and includes a top 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 positive electrode tabs 112p protruding from the first end portion 13, and the negative electrodes 120 include negative electrode tabs 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 chamfered shapes.

[0069] 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 positions 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 an 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. The separator 130 is configured by connecting the first outer separator 133, the first outer folded portion 136, the inner separator 135, the second outer folded portion 137, and the second outer separator 134.

[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 folded 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 that is arranged on the positive electrode 110 (negative electrode arrangement step), and a step of folding back the separator 130. The method includes 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 arranging the separator 130 on the negative electrode 120 (second folding step), a step of arranging the positive electrode 110 on the separator 130 that is arranged on the negative electrode 120 (second positive electrode arrangement step), a step of folding back the separator 130 to form a second outer folded portion 137 that positions the positive electrode 110 relative to the separator 130 and arranging the separator 130 on the positive electrode 110 (second outer folding step), and a step of heating the first outer folded portion 136 and the second outer folded portion 137 to form a chamfered shape (chamfering step).

[0072] The manufacturing method of the electrode body 100 in this embodiment includes a chamfering step, which 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, by hardening the separator by heating. This prevents damage to portions of the electrode assembly 100 other than the chamfered portion even if the cell case and the chamfered portion of the electrode assembly 100 come into contact when the electrode assembly 100 is inserted into the cell case.

[0074] As described above, in the electrode assembly 100 and its manufacturing method according to this embodiment, the first external folded portion 136 and the second external folded portion 137 are provided at the first ends 13 of the first external separator 133 and the second external separator 134, which are arranged at the outermost parts in the thickness direction of the electrode assembly 100, and the first external folded portion 136 and the second external folded portion 137 form a chamfered shape. By inserting the electrode assembly 100 having such a shape into the cell case from the first end 13 having the chamfered shape, the electrode assembly 100 can be smoothly inserted into the cell case. Furthermore, because the chamfered shape is formed by heating, even if the cell case and the chamfered portion of the electrode assembly 100 come into contact when inserting the electrode assembly 100 into the cell case, damage to portions of the electrode assembly 100 other than the chamfered portion is suppressed.

[0075] 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 disclosure 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]

[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. The battery includes 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 separators for insulating the positive electrodes and the negative electrodes from each other; 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 a top 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 include positive electrode tabs protruding from the first end; the plurality of negative electrodes include negative electrode tabs 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 first welded portion, the second welded portion, the third welded portion, and the fourth welded portion are formed of a resin, the height of the first welded portion and the height of the second welded portion are each equal to or greater than one-third and equal to or less than one-half of the height of the electrode body, the third welded portion and the fourth welded portion are disposed at a distance from each other with a central portion of the bottom portion sandwiched therebetween, A storage cell, wherein the widthwise length of the third welded portion and the widthwise length of the fourth welded portion are each between one-fourth and one-third of the widthwise length of the electrode body.

2. The separator is formed in a zigzag shape, the separator has a first folded portion and a second folded portion, the first folded portion is formed at the first end portion, The energy storage cell according to claim 1 , wherein the second folded portion is formed at the second end portion.

3. The separator is formed in a zigzag shape, the separator includes a first outer separator, a second outer separator, an inner separator, a first outer folded portion, and a second outer folded portion; the first outer folded portion connects the first outer separator and the inner separator; the second outer folded portion connects the second outer separator and the inner separator, the internal separator has a first folded portion and a second folded portion; the first folded portion, the first outer folded portion, and the second outer folded portion are formed on the first end portion, the second folded portion is formed at the second end portion, The energy storage cell according to claim 1 , wherein the first outer folded portion and the second outer folded portion have a chamfered shape.

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