Power storage cell and method for manufacturing electrode body

Abstract

Provided are an electricity storage cell and a method for manufacturing an electrode body. An electricity storage cell is provided with an electrode body, a cell case for housing the electrode body, and an electrolyte solution housed in the cell case. The electrode body includes a plurality of positive electrodes and a plurality of negative electrodes arranged side by side 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 longer than the thickness direction in a width direction orthogonal to both the thickness direction and the vertical direction. The electrode body includes an upper portion, a bottom portion, a first end portion at one end in the width direction, and a second end portion at the other end in the width direction. The plurality of electrodes includes a plurality of positive electrodes and a plurality of negative electrodes. The plurality of positive electrodes includes a positive tab protruding from a first end portion. The plurality of negative electrodes includes a negative tab protruding from the second end portion. A first welded portion is formed at the first end portion at a portion lower than the positive electrode tab. A second welding part is formed at the second end part at a part lower than the negative electrode tab. A third welding part which is in contact with the first welding part and a fourth welding part which is in contact with the second welding part are formed on the bottom part. The third welded portion and the fourth welded portion are disposed at a distance from each other across the central portion of the bottom portion.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a power storage cell and an electrode body. Background Art

[0002] Japanese Patent Application Laid-Open No. 2009-88279 discloses a method of bonding electrodes and a separator or bonding separators to each other in an electrode body formed by stacking electrodes including a binder with a separator interposed therebetween using an adhesive mainly composed of the same component as the binder of the electrodes. Summary of the invention

[0003] The electrode body repeatedly expands and contracts by repeated charge and discharge. At this time, the electrolyte enters and exits from the periphery of the electrode body. In the electrode body formed horizontally, the electrolyte is maintained in the surrounding part by entering and exiting from the periphery of the electrode body. On the other hand, as time passes, the electrolyte is easily exhausted inside the electrode body, especially in the center. As a result, the penetration of the electrolyte inside the electrode body may become uneven.

[0004] An object of the present disclosure is to provide a power storage cell in which penetration of an electrolyte into an electrode body is less likely to become uneven.

[0005] [1] A storage cell, comprising: an electrode body; a battery cell case for accommodating the electrode body; and an electrolyte solution accommodated in the battery cell case, the electrode body comprising: a plurality of positive electrodes and a plurality of negative electrodes arranged in a thickness direction; and a separator for insulating each positive electrode from each negative electrode, the electrode body having a shape that is longer in a width direction that is orthogonal to both the thickness direction and the up-down direction than in the thickness direction, the electrode body comprising 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 include a positive electrode tab protruding from the first end, and the plurality of negative electrodes include a negative electrode tab protruding from the second end. A first welding portion is formed at a portion located below the positive electrode tab at the first end, and a second welding portion is formed at a portion located below the negative electrode tab at the second end. A third welding portion connected to the first welding portion and a fourth welding portion connected to the second welding portion are formed at the bottom, and the third welding portion and the fourth welding portion are arranged at intervals across a central portion of the bottom.

[0006] The electrode body expands and contracts during charge and discharge. The electrolyte enters and exits the electrode body through the expansion and contraction of 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 at both ends in the width direction of the electrode body and at both ends in the width direction of the bottom of the electrode body, the electrolyte can be blocked from entering and exiting the welded portions. As a result, the electrolyte can be maintained in a state of infiltration into the corners of the bottom of the electrode body. Therefore, the infiltration of the electrolyte is less likely to become uneven inside the electrode body.

[0007] Figure 1 Schematic diagram showing the degree of electrolyte penetration in an electrode body without a welded portion. Figure 1 In the figure, 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, the electrolyte that has penetrated into the corner of the bottom of the electrode body penetrates into the electrode body over time. Figure 1 It is considered that the zone Z in the center portion where the electrolyte is difficult to penetrate is suppressed, thereby suppressing the variation in the degree of penetration of the electrolyte.

[0008] [2] The power storage unit according to [1], wherein a height of the first weld portion and a height of the second weld portion are not less than one third and not more than one half of a height of the electrode body.

[0009] [3] The power storage unit according to [1] or [2], wherein the length of the third weld portion in the width direction and the length of the fourth weld portion in the width direction are not less than one quarter and not more than one third of the length of the electrode body in the width direction.

[0010] [4] A method for manufacturing an electrode body, which is a method for manufacturing an electrode body in which a positive electrode and a negative electrode are arranged in an arrangement with a partition between them, wherein the method comprises: a step of preparing the partition; a step of placing the positive electrode on the partition; a step of folding the partition back to form a folded portion for positioning the positive electrode relative to the partition, and placing the partition on the positive electrode; a step of heating the partition to fuse the partition to the positive electrode; a step of placing the negative electrode on the partition fused to the positive electrode; a step of folding the partition back to form a folded portion for positioning the negative electrode relative to the partition, and placing the partition on the negative electrode; and a step of heating the partition to fuse the partition to the negative electrode.

[0011] The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram showing the degree of penetration of the electrolyte in the electrode body where no weld portion is formed.

[0013] Figure 2 This is an example of a perspective view schematically showing the power storage unit in the first embodiment.

[0014] Figure 3 yes Figure 2 A cross-sectional view of a power storage unit shown.

[0015] Figure 4A and Figure 4B This is an example of a perspective view schematically showing the electrode body in the first embodiment.

[0016] Figure 5 This is a diagram schematically showing an electrode body in the second embodiment.

[0017] Figure 6 This is a diagram schematically showing a method for manufacturing an electrode assembly in the second embodiment.

[0018] Figure 7 This is a diagram schematically showing a method for manufacturing an electrode assembly in the second embodiment.

[0019] Figure 8 This is a diagram schematically showing a method for manufacturing an electrode assembly in the second embodiment.

[0020] Fig. 9 This is a diagram schematically showing a method for manufacturing an electrode assembly in the second embodiment.

[0021] Fig.10 This is a diagram schematically showing an electrode body in the third embodiment.

[0022] Fig.11 This is a diagram schematically showing a method for manufacturing an electrode assembly in the third embodiment.

[0023] Fig.12 This is a diagram schematically showing a method for manufacturing an electrode assembly in the third embodiment.

[0024] Fig.13 This is a diagram schematically showing a method for manufacturing an electrode assembly in the third embodiment.

[0025] Fig.14 This is a diagram schematically showing a method for manufacturing an electrode assembly in the third embodiment.

[0026] Fig.15 This is a diagram schematically showing a method for manufacturing an electrode assembly in the third embodiment.

[0027] Fig.16 This is a diagram schematically showing a method for manufacturing an electrode assembly in the third embodiment.

[0028] Fig.17 This is a diagram schematically showing an electrode body in the fourth embodiment. DETAILED DESCRIPTION

[0029] <Implementation Method 1>

[0030] The power storage unit in 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.

[0031] Figure 2 This is an example of a perspective view schematically showing the power storage unit in the present embodiment. Figure 3 yes Figure 2 A cross-sectional view of a power storage unit shown. Figure 4A and Figure 4B This is an example of a perspective view schematically showing the electrode body in this embodiment.

[0032] like Figure 2 and Figure 3 As shown, the power storage cell 1 includes an electrode body 100 , a cell case 200 , a pair of external terminals 300 , a pair of connecting members 400 , an insulating member 500 , and an electrolyte solution (not shown).

[0033] The electrode body 100 has a Figure 2 The electrode body 100 is formed to have a plurality of positive electrodes 110 and a plurality of negative electrodes 120 arranged in a manner of being arranged on a T in the figure, and a separator 130 for insulating each positive electrode 110 from each negative electrode 120. Figure 2 H) in the orthogonal directions ( Figure 2 The electrode body 100 has a rectangular shape that is longer in the width direction 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.

[0034] Each positive electrode 110 is formed into a rectangular shape that is long in the width direction. Each positive electrode 110 includes a positive current collector foil and a positive active material layer disposed on both sides of the positive current collector foil. The positive electrode 110, specifically the positive current collector foil, includes a positive tab 112p that protrudes from the first end 13 toward one side in the width direction. No positive active material layer is disposed on the positive tab 112p.

[0035] Each negative electrode 120 is formed into a rectangular shape that is long in the width direction. Each negative electrode 120 includes a negative electrode collector foil and a negative electrode active material layer provided on both sides of the negative electrode collector foil. The negative electrode 120, specifically the negative electrode collector foil, includes a negative electrode tab 122n protruding from the second end 14 toward one side in the width direction. No negative electrode active material layer is provided on the negative electrode tab 122n.

[0036] A first weld 15 is formed at the first end 13 at a portion located below the positive electrode tab 112p. A second weld 16 is formed at the second end 14 at a portion located below the negative electrode tab 122n. A third weld 17 connected to the first weld 15 and a fourth weld 18 connected to the second weld 16 are formed at the bottom 12. With such a structure, the inflow and outflow of the electrolyte in the first weld 15, the second weld 16, the third weld 17, and the fourth weld 18 can be blocked. As a result, the electrolyte can be maintained in the corners of the bottom 12 (near the first weld 15 and the third weld 17 and near the second weld 16 and the fourth weld 18). Therefore, the electrolyte is less likely to be unevenly infiltrated inside the electrode body 100.

[0037] The first weld 15, the second weld 16, the third weld 17, and the fourth weld 18 may be formed of resin, for example. The first weld 15, the second weld 16, the third weld 17, and the fourth weld 18 may be formed of the same resin or different resins.

[0038] The height H1 of the first weld 15 and the height H2 of the second weld 16 are preferably not less than one third and not more than one half of the height of the electrode body 100. By setting the heights to such values, it is expected that the electrolyte can be more uniformly infiltrated.

[0039] The third weld 17 and the fourth weld 18 are arranged at a distance across the central portion of the bottom 12. This is because if the weld is formed on the entire bottom 12, the electrolyte cannot enter or exit the bottom 12.

[0040] The widthwise length W1 of the third weld 17 and the widthwise length W2 of the fourth weld 18 are preferably not less than one quarter and not more than one third of the widthwise length of the electrode body 100. By setting such lengths, it is expected that the electrolyte can be more uniformly infiltrated.

[0041] The separator 130 insulates the positive electrode 110 from the negative electrode 120. The separator 130 is made of an insulating material and has minute gaps that allow ions to pass through.

[0042] The battery cell case 200 houses the electrode assembly 100 . An electrolyte solution (not shown) is housed in the battery cell case 200 . The battery cell case 200 is sealed. The battery cell case 200 includes a case body 210 and a lid 220 .

[0043] The housing body 210 has an opening portion that opens upward. The housing body 210 is made of metal such as aluminum. Figure 3 As shown, the housing body 210 has a bottom wall 212 and a peripheral wall 214. The bottom wall 212 is formed in a rectangular and flat plate shape. The peripheral wall 214 stands up from the bottom wall 212. The peripheral wall 214 is formed in a square 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.

[0044] The cover 220 closes the opening of the housing body 210. The cover 220 is connected to the opening by welding or the like. The cover 220 is formed in a flat plate shape. The cover 220 is made of a metal such as aluminum. The cover 220 has a pressure release valve 222 and a sealing member 224.

[0045] The pressure release valve 222 is formed in the center of the cover 220. The pressure release valve 222 is formed to rupture when the internal pressure of the battery cell case 200 reaches a predetermined pressure or more. When the pressure release valve 222 ruptures, the gas in the battery cell case 200 is released to the outside of the battery cell case 200 through the pressure release valve 222, so that the internal pressure of the battery cell case 200 is reduced.

[0046] The sealing member 224 seals the injection port h formed in the cover 220. The injection port h is a through hole for injecting electrolyte into the battery cell case 200 during the manufacturing process of the power storage unit 1. After the electrolyte is injected into the case body 210 through the injection port h, the injection port h is sealed by the sealing member 224.

[0047] A pair of external terminals 300 are fixed to the battery cell housing 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 cover 220 via an upper insulating portion 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.

[0048] A pair of connecting members 400 connects the plurality of electrode tabs 112p and 122n to the external terminal 300. One connecting member 400 connects the plurality of positive electrode tabs 112p to the positive external terminal 300, and the other connecting member 400 connects the plurality of negative electrode tabs 122n to the negative external terminal 300. The pair of connecting members 400 have substantially the same structure, so one connecting member 400 will be described below.

[0049] The connecting member 400 includes a current collecting tab 410 , an auxiliary tab 420 , and a connecting pin 430 .

[0050] The current collecting tab 410 has a side portion 412 and an upper portion 414. The side portion 412 is located on the side of the electrode body 100 in the width direction. The upper portion 414 is located above the electrode body 100. The upper portion 414 extends from the upper end of the side portion 412 toward the inner side in the width direction.

[0051] The secondary contact 420 connects the plurality of positive electrode contacts 112p to the current collecting contact 410. One end 422 of the secondary contact 420 is connected to the plurality of positive electrode contacts 112p by welding or the like, and the other end 424 of the secondary contact 420 is connected to the side portion 412 of the current collecting contact 410 by welding or the like.

[0052] The connecting pin 430 connects the current collecting tab 410 to the external terminal 300. The connecting pin 430 connects the upper portion 414 to the external terminal 300. Specifically, the lower end of the connecting pin 430 is connected to the upper portion 414 by welding or the like while being inserted into a through hole provided in the upper portion 414, and the upper end of the connecting pin 430 is connected to the external terminal 300 by welding, riveting or the like while being inserted into a through hole provided in the external terminal 300.

[0053] The insulating member 500 insulates the battery cell case 200 from the connecting member 400. The insulating member 500 includes an upper insulating portion 510, a lower insulating portion 520, an insulating member 530, and an insulating plate 540.

[0054] The upper insulating portion 510 is fixed to the upper surface of the cover 220. The upper insulating portion 510 is disposed between the cover 220 and the external terminal 300. The upper insulating portion 510 is provided with an insertion hole through which the coupling pin 430 is inserted.

[0055] The lower insulating portion 520 is fixed to the lower surface of the cover 220. The lower insulating portion 520 is disposed between the cover 220, the upper portion 414, and the lower portion of the connecting pin 430. The lower insulating portion 520 is provided with an insertion hole through which the connecting pin 430 is inserted.

[0056] The insulating member 530 is disposed between the connecting pin 430 and the cover 220. The insulating member 530 is formed in a cylindrical shape and surrounds the connecting pin 430.

[0057] The insulating plate 540 is fixed to the lower surface of the upper portion 414. The insulating plate 540 is disposed above the electrode body 100. Through holes are provided in the insulating plate 540 at a portion below the pressure release valve 222 and a portion below the liquid injection port h.

[0058] As described above, in the power storage unit 1 of the present embodiment, the first weld 15 and the second weld 16 are respectively formed below the first end 13 and the second end 14 located at both ends in the width direction of the electrode body 100. In addition, the third weld 17 and the fourth weld 18 are respectively formed at both ends of the bottom 12 of the electrode body 100. With such a configuration, the inflow and outflow of the electrolyte in the first weld 15, the second weld 16, the third weld 17, and the fourth weld 18 can be blocked, and the penetration of the electrolyte into the electrode body 100 is less likely to become uneven.

[0059] <Implementation Method 2>

[0060] In this embodiment, an electrode body and a method for manufacturing the electrode body that can be used in Embodiment 1 are described with reference to the drawings. In addition, about the same contents as Embodiment 1, repeated description is omitted.

[0061] Figure 5 1 is a diagram schematically showing an electrode body in the present embodiment. The electrode body 100 in the present embodiment includes a plurality of positive electrodes 110 and a plurality of negative electrodes 120 arranged in a manner arranged in the thickness direction, and a separator 130 formed in a meandering shape and used to insulate each positive electrode 110 and each negative electrode 120. The separator 130 has a shape that is longer in the width direction orthogonal 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 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 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 .

[0062] The separator 130 of the electrode body 100 in this embodiment is formed in a meandering 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 way, the positional displacement of the positive electrode 110 and the negative electrode 120 relative to the separator 130 can be suppressed.

[0063] Next, the manufacturing process of the electrode body 100 is described. The manufacturing method of the electrode body 100 in the present embodiment is a manufacturing method of the electrode body 100 in which the positive electrode 110 and the negative electrode 120 are arranged in an array with the separator 130 interposed therebetween, including: a process of preparing the separator 130 (preparation process); a process of arranging the positive electrode 110 on the separator 130 (positive electrode arrangement process); a process of folding back the separator 130 to form a first folded portion 131 for positioning the positive electrode 110 relative to the separator 130, and arranging the separator 130 on the positive electrode 110 (positive electrode arrangement process); The invention further comprises the following steps: a first folding step; a step of arranging the negative electrode 120 on the partition 130 arranged on the positive electrode 110 (negative electrode arrangement step); a second folding portion 132 for positioning the negative electrode 120 relative to the partition 130 is formed by folding the partition 130, and a step of arranging the partition 130 on the negative electrode 120 (second folding step); and a step of heating the first folding portion 131 and the second folding portion 132 to fuse them to the positive electrode 110 and the negative electrode 120 (fusion process).

[0064] In the preparation step, the long-strip separator 130 is prepared.

[0065] In the positive electrode placement step, the positive electrode 110 is placed on the separator 130. Figure 6 Indicates the state after the positive electrode arrangement step.

[0066] In the first folding step, the separator 130 is folded back in such a manner that the separator 130 is arranged on the positive electrode 110. Thus, a first folded back portion 131 is formed on the separator 130. The positive electrode 110 is positioned relative to the separator 130 by the first folded back portion 131. That is, in this step, the first folded back portion 131 for positioning the positive electrode 110 relative to the separator 130 is formed by folding back the separator 130, and the separator 130 is arranged on the positive electrode 110. In addition, Figure 7 The state after the first folding step is shown.

[0067] In the negative electrode placement step, the negative electrode 120 is placed on the separator 130 placed on the positive electrode 110. Figure 8 Indicates the state after the negative electrode arrangement step.

[0068] 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 disposed on the negative electrode 120. Fig. 9 The state after the second folding step is shown.

[0069] Thereafter, the positive electrode placement step, the first folding step, the negative electrode placement step, and the second folding step are repeated in sequence.

[0070] In the welding step, the first folded portion 131 and the second folded portion 132 are heated to be welded to the positive electrode 110 and the negative electrode 120. The heating method is not particularly limited, and examples thereof include a heater.

[0071] In the welding process, it is further preferred to heat at least one of the groups consisting of the upper part 11 and the bottom part 12 so that the separator 130 is welded to the positive electrode 110 and the negative electrode 120. The electrode body 100 is mounted on a vehicle, for example. When mounted on a vehicle, vibrations are mostly applied in the up and down directions. Therefore, in the electrode body 100, by heating at least one of the groups consisting of the upper part 11 and the bottom part 12 as the up and down directions thereof, the positional deviation of the positive electrode 110 and the negative electrode 120 relative to the separator 130 can be further suppressed. In the welding process, it is more preferred to heat the upper part 11 and the bottom part 12 so that they are welded to the positive electrode 110 and the negative electrode 120.

[0072] The upper portion 11 and the bottom portion 12 may be heated in their entirety or only in part. The upper portion 11 and the bottom portion 12 are preferably heated in their entirety.

[0073] As described above, in the electrode body 100 and its manufacturing method in the present embodiment, the first folded portion 131 and the second folded portion 132 of the separator 130 are heated and melted, so that the positive electrode 110 and the negative electrode 120 are positioned relative to the separator 130, thereby achieving the suppression of positional deviation of the positive electrode 110 and the negative electrode 120 relative to the separator 130.

[0074] <Implementation Method 3>

[0075] In this embodiment, an electrode body and a method for manufacturing the electrode body that can be used in Embodiment 1 are described with reference to the drawings. In addition, about the same contents as Embodiments 1 and 2, repeated description is omitted.

[0076] Fig.10 1 is a diagram schematically showing an electrode body in this embodiment. The electrode body 100 in this embodiment has the same structure as that of the second embodiment.

[0077] The manufacturing method of the electrode body 100 in this embodiment is partially different from that in the second embodiment. The manufacturing method of the electrode body 100 in this embodiment is a manufacturing method of the electrode body 100 in which the positive electrode 110 and the negative electrode 120 are arranged in a manner of being separated by the separator 130, including: a process of preparing the separator 130 (preparation process); a process of arranging the positive electrode 110 on the separator 130 (positive electrode arrangement process); a process of folding back the separator 130 to form a folded portion 131 for positioning the positive electrode 110 relative to the separator 130, and arranging the separator 130 on the positive electrode 110 (first folding process); ); a process of heating the first folded portion 131 and welding it to the positive electrode 110 (a first welding process); a process of configuring the negative electrode 120 on the partition 130 configured on the positive electrode 110 (a negative electrode configuration process); a process of forming a folded portion 132 for positioning the negative electrode 120 relative to the partition 130 by folding back the partition 130, and configuring the partition 130 on the negative electrode 120 (a second folding process); and a process of heating the second folded portion 132 and welding it to the negative electrode 120 (a second welding process).

[0078] The manufacturing method of the electrode body 100 in this embodiment is different from 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 are described below. It should be noted that: Fig.11 Indicates the state after the positive electrode configuration process, Fig.12 Indicates the status after the first folding process. Fig.14 Indicates the state after the negative electrode configuration process, Fig.15 Indicates the state after the second folding step.

[0079] In the first welding step, the first folded portion 131 is heated and welded to the positive electrode 110. Fig.13 This shows the state after the first welding step.

[0080] In the second welding step, the second folded portion 132 is heated and welded to the negative electrode 120. Fig.16 It shows the state after the second welding step.

[0081] In the present embodiment, the positive electrode arrangement step, the first folding step, the first welding step, the negative electrode arrangement step, the second folding step, and the second welding step are repeated in this order.

[0082] In the present embodiment, a third welding step of heating 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 may be included. In the third welding step, the upper portion 11 and the bottom portion 12 are preferably heated to weld them to the positive electrode 110 and the negative electrode 120.

[0083] The upper portion 11 and the lower portion 12 may also be heated while the first folded portion 131 and the second folded portion 132 are heated in the first welding step and the second welding step, so that the separator 130 is welded to the positive electrode 110 and the negative electrode 120. Fig.13 and Fig.16 In the case shown, the separator 130 may be fused to the positive electrode 110 and the negative electrode 120 by heating the upper and lower parts in sequence during the electrode body formation process while heating the first and second folded parts 131 and 132 .

[0084] As described above, in the electrode body 100 and its manufacturing method in the present embodiment, the first folded portion 131 and the second folded portion 132 of the separator 130 are heated and melted, so that the positive electrode 110 and the negative electrode 120 are positioned relative to the separator 130, thereby achieving the suppression of positional deviation of the positive electrode 110 and the negative electrode 120 relative to the separator 130.

[0085] <Implementation Method 4>

[0086] In this embodiment, an electrode body and a method for manufacturing the electrode body that can be used in Embodiment 1 are described with reference to the drawings. In addition, for the same contents as Embodiments 1 to 3, repeated descriptions are omitted.

[0087] Fig.171 is a diagram schematically showing an electrode body in the present embodiment. The electrode body 100 in the present embodiment includes a plurality of positive electrodes 110 and a plurality of negative electrodes 120 arranged in a manner arranged in the thickness direction, and a separator 130 formed in a meandering shape and used to insulate each positive electrode 110 and each negative electrode 120, and has a shape that is longer in the width direction orthogonal 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 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 external separator 133, a second external separator 134, an internal separator 135, a first external folded portion 136, and a second external folded portion 137. The first outer folded portion 136 connects the first outer partition 133 and the inner partition 135. The second outer folded portion 137 connects the second outer partition 134 and the inner partition 135. The inner partition 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.

[0088] like Fig.17 As shown, the separator 130 of the electrode body 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 body 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 body 100 having such a shape, the electrode body 100 can be smoothly inserted into the battery cell case by inserting the battery cell case from the first end portion 13 having a chamfered shape. In addition, the separator 130 is configured such that the first external separator 133, the first external folded portion 136, the internal separator 135, the second external folded portion 137 and the second external separator 134 are connected as a whole.

[0089] The chamfered shape is not particularly limited, and does not have to be a sharp corner portion, as long as it is a plane shape having an angle (a plane shape having rounded corners).

[0090] The manufacturing method of the electrode body 100 in the present embodiment is a manufacturing method of the electrode body 100 in which the positive electrode 110 and the negative electrode 120 are arranged in an array with a separator 130 interposed therebetween, comprising: a process of preparing the separator 130 (preparation process); a process of arranging the positive electrode 110 on the separator 130 (first positive electrode arrangement process); a process of folding back the separator 130 to form a first external folding portion 136 for positioning the positive electrode 110 relative to the separator 130, and arranging the separator 130 on the positive electrode 110 (first external folding process); a process of arranging the negative electrode 120 on the separator 130 arranged on the positive electrode 110 (negative electrode arrangement process); A process of forming a folded portion 132 for positioning the negative electrode 120 relative to the partition 130 by folding back the partition 130, and arranging the partition 130 on the negative electrode 120 (a second folding process); a process of arranging the positive electrode 110 on the partition 130 arranged on the negative electrode 120 (a second positive electrode arrangement process); a process of forming a second external folded portion 137 for positioning the positive electrode 110 relative to the partition 130 by folding back the partition 130, and arranging the partition 130 on the positive electrode 110 (a second external folding process); and a process of heating the first external folded portion 136 and the second external folded portion 137 to form a chamfered shape (a chamfering process).

[0091] The method for manufacturing the electrode body 100 in the present embodiment includes a chamfering step. The chamfering step will be described below.

[0092] In the chamfering process, the first outer folded portion 136 and the second outer folded portion 137 are heated to form a chamfered shape. The chamfered shape is formed by heating, that is, the separator is solidified by heating. Thus, when the electrode body 100 is inserted into the battery cell case, even if the battery cell case contacts the chamfered portion of the electrode body 100, it is possible to suppress damage to the portion other than the chamfered portion of the electrode body 100.

[0093] As described above, in the electrode body 100 and the manufacturing method thereof in the present 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 disposed at the outermost portion 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, the electrode body 100 can be smoothly inserted into the battery cell case by inserting the battery cell case from the first end 13 having the chamfered shape. In addition, the chamfered shape is formed by heating, so that when the electrode body 100 is inserted into the battery cell case, even if the battery cell case contacts the chamfered portion of the electrode body 100, it is possible to suppress damage to the portion other than the chamfered portion of the electrode body 100.

[0094] Although the embodiments of the present invention have been described, the embodiments disclosed this time should be considered to be illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the scope of claims, and it is intended to include all changes within the meaning and scope equivalent to the scope of claims.

Claims

1. A power storage unit comprising: an electrode body; a battery cell housing for accommodating the electrode body; and an electrolyte contained in the battery cell housing, The electrode body comprises: a plurality of positive electrodes and a plurality of negative electrodes arranged in a thickness direction; and a separator for insulating the positive electrodes and the negative electrodes. The electrode body has a shape that is longer in a width direction perpendicular to both the thickness direction and the up-down 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 include a positive tab protruding from the first end, The plurality of negative electrodes include a negative tab protruding from the second end, A first weld portion is formed at the first end portion at a portion located below the positive electrode tab. A second weld portion is formed at the second end portion at a portion located below the negative electrode tab. The bottom portion includes a third weld portion connected to the first weld portion and a fourth weld portion connected to the second weld portion. The third welded portion and the fourth welded portion are arranged at a distance from each other across a central portion of the bottom portion.

2. The power storage unit according to claim 1, wherein: The height of the first weld portion and the height of the second weld portion are respectively not less than one third and not more than one half of the height of the electrode body.

3. The power storage unit according to claim 1 or 2, wherein: The length of the third weld portion in the width direction and the length of the fourth weld portion in the width direction are each not less than one quarter and not more than one third of the length of the electrode body in the width direction.

4. A method for manufacturing an electrode body, wherein a positive electrode and a negative electrode are arranged in an array with a separator interposed therebetween, wherein: have: A process for preparing the separator; a step of 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; The process of heating the separator to fuse the separator to the positive electrode; The step of disposing the negative electrode on the separator welded to 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 A step of heating the separator to fuse the separator to the negative electrode.

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