Method for manufacturing power storage device

Abstract

Provided is a method for manufacturing a power storage device, wherein the power storage capacity per unit volume of a case can be improved, and the buckling deformation of a sealing body to which a current collector terminal is joined can be suppressed by reducing the positional displacement of the current collector terminal when joining an electrode foil and the current collector terminal. The electricity storage device is provided with: an electrode body which is housed in a case and in which a positive electrode body and a negative electrode body are laminated with a separator interposed therebetween, the positive electrode body and the negative electrode body having an active material coated portion and an active material non-coated portion on an electrode foil; and a collector terminal having a base portion coupled to both end portions of the case in the longitudinal direction, and a lead portion to which the active material non-coated portion in the overlapping state is joined. Wherein the method comprises: a preliminary bending step for bending the active material non-coated portion in an overlapping state, forming a fold at a boundary portion with the active material coated portion, and then releasing the fold; and a current collector terminal bonding step in which, after the preliminary bending step, the active material non-coated portion is re-bent and bonded to the lead portion.

Description

Technical Field

[0001] The disclosed technology relates to a method for manufacturing an electrical storage device capable of reducing positional deviation of a current collector terminal joined to an electrode body and suppressing warping deformation of a sealing body to which the current collector terminal is joined. Background Art

[0002] In the past, when joining the electrode foil (active material non-coated portion) at the axial end of the stacked electrode body to the collector terminal, a joining tool (e.g., a welding head or an ultrasonic horn) often pressurizes the collector terminal and multiple pieces of electrode foil together to overlap the electrode foil and join them to the collector terminal (resistance welding or ultrasonic joining). In this case, the collector terminal slides relative to the electrode foil in the middle of the overlap, causing the joining portion of the collector terminal to shift in the axial (lateral) direction of the electrode body. Therefore, the long strip-shaped housing that accommodates the electrode body and is combined with the collector terminal is prone to warping deformation in which the central portion of its long side is displaced in the upward and downward directions. As a result, for example, there is a problem that the measurement accuracy of the temperature sensor that monitors the battery temperature is reduced due to contact with the upper surface of the housing.

[0003] Regarding this point, for example, Patent Document 1 discloses a terminal joining method. This terminal joining method comprises the following steps: when joining the electrode foil to the collector terminal, a pressing unit is used to press the electrode foil from both sides in the stacking direction so that the joined portion of the electrode foil is closer to the active material coating portion of the electrode body. With the electrode foils pre-overlapped, the electrode foils are joined to the collector terminal. According to the terminal joining method described above, since the electrode foils are pre-overlapped, the problem of the joined portion of the collector terminal being less likely to shift in the axial direction occurs. As a result, warping deformation of the housing to which the collector terminal is attached can be suppressed, and for example, the measurement accuracy of a temperature sensor in contact with the upper surface of the housing can be improved.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-22203

[0005] However, in this case, the pressing unit squeezes the electrode foil from both sides of the stacking direction, bringing the joined portion closer to the active material coating than the portion that joins the current collector terminal. Therefore, the joining tool must form the joined portion of the electrode foil in a position that does not interfere with the pressing unit. Consequently, the joined portion of the electrode foil must be extended away from the active material coating of the electrode body. This increases the volume of the housing, resulting in a decrease in the storage capacity per unit volume of the housing, which is not ideal. Summary of the Invention

[0006] The technology disclosed herein was developed in light of this problem, and its purpose is to provide a method for manufacturing a storage device that can increase the storage capacity per unit volume of the casing and, by reducing positional deviation of the collector terminals when joining the electrode foil to the collector terminals, thereby suppressing warping deformation of the casing to which the collector terminals are attached.

[0007] (1) One form of the disclosed technology for solving the above-mentioned problems is a method for manufacturing an electrical storage device, the electrical storage device comprising: a housing; an electrode body housed in the housing, formed by stacking a positive electrode body and a negative electrode body with a separator interposed therebetween, the positive electrode body and the negative electrode body having an active material coated portion on an electrode foil coated with an active material, and an active material non-coated portion on each of the ends of the electrode foil facing each other in the long side direction of the housing, the active material not being coated; and positive and negative current collecting terminals having a connection with the long side of the housing via an insulating member. A base portion coupled to both ends, and a lead portion joined to the above-mentioned active material non-coated portion in an overlapping state, wherein the manufacturing method of the above-mentioned storage device comprises: a preliminary bending step, bending the above-mentioned active material non-coated portion into an overlapping state, forming a crease in the above-mentioned active material non-coated portion at the boundary with the above-mentioned active material coated portion, and then releasing the active material non-coated portion in the overlapping state; and a collector terminal joining step, after the above-mentioned preliminary bending step, bending the above-mentioned active material non-coated portion again into an overlapping state and then joining it to the above-mentioned lead portion.

[0008] (2) According to the method for manufacturing an electric storage device described in (1), preferably, in the preliminary bending step, the active material non-coated portion is bent a plurality of times into an overlapping state. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic cross-sectional view of an electric storage device manufactured by a manufacturing method according to one aspect of the present embodiment.

[0010] Figure 2 It means to put the diaphragm between Figure 1 The diagram is a schematic perspective view of an electrode assembly in which a positive electrode body and a negative electrode body are stacked and wound in a state in progress.

[0011] Figure 3 yes Figure 1 AA section view shown.

[0012] Figure 4 yes Figure 1 An enlarged cross-sectional view of portion B is shown.

[0013] Figure 5 Yes Figure 1 Flowchart of a method for manufacturing an electrical storage device shown.

[0014] Figure 6A It is used Figure 4 The CC cross section shown represents Figure 5 Schematic cross-sectional view of the stacked state of the electrode assembly before the preliminary bending step.

[0015] Figure 6B It will Figure 6A The active material non-coated portion shown is a schematic cross-sectional view when the active material non-coated portion is bent in an overlapping state to form a fold at the boundary with the active material coated portion.

[0016] Figure 6C Release from the overlapping state Figure 6B Schematic cross-sectional view of the active material non-coated portion shown.

[0017] Figure 7A is Figure 6C This is a schematic cross-sectional view of a case where a current collecting terminal is provided on the active material non-coated portion.

[0018] Figure 7B It will Figure 7A The active material non-coated portion shown is a schematic cross-sectional view of the state where the current collecting terminal is joined after the portion is bent again into an overlapping state.

[0019] Figure 7C It will Figure 7B Schematic cross-sectional view showing a state where the active material non-coated portion and the current collector terminal are completely joined.

[0020] Figure 8 This is a schematic cross-sectional view showing a state in which a joining tool is pressing both the current collector terminal and the active material non-coated portion to overlap and join the active material non-coated portion to the current collector terminal in a method of manufacturing an electrical storage device according to a comparative example.

[0021] Description of Reference Numerals

[0022] 1…housing; 2…electrode body; 3…insulating component; 4, 4A, 4B…collector terminal; 10…electrical storage device; 21…positive electrode body; 22…negative electrode body; 23…separator; 21K, 22K…electrode foil; 21K1, 22K1…one end portion; 41…base portion; 43…lead portion; 43b…lower end portion of lead; 211, 221…active material non-coated portion; 212, 222…active material coated portion; KR…boundary portion; KT1, KT2…active material; QP…crease; S1…preliminary bending step; S2…collector terminal joining step. DETAILED DESCRIPTION

[0023] <Description of this energy storage device>

[0024] Next, the structure of the electric storage device manufactured by the manufacturing method according to the embodiment of the above-mentioned disclosed technology will be described in detail with reference to the accompanying drawings. Figure 1 1 is a schematic cross-sectional view of an electric storage device manufactured by a manufacturing method according to one aspect of this embodiment. Figure 2 The diagram shows the laminated and wound layers with the separator sandwiched between them. Figure 1 The schematic perspective view of the positive electrode body and the negative electrode body of the electrode body shown in FIG. Figure 3 Shown in Figure 1 AA section view shown. In addition, Figure 1 、 Figure 3 The X direction shown indicates the long side direction of the sealing body, the Y direction indicates the short side direction of the sealing body, and the Z direction indicates the up-down direction of the housing.

[0025] like Figures 1 to 3 As shown, an electrical storage device 10 manufactured using a manufacturing method according to an embodiment of the presently disclosed technology includes a case 1, an electrode assembly 2, and a current collector terminal 4. Here, the case 1 includes a case body 11 having a bottomed, square cylindrical shape and a rectangular opening 111, and a long, flat-plate-shaped sealing member 12 that seals the opening 111. Both the case body 11 and the sealing member 12 are made of aluminum. However, since the sealing member 12 is required to improve the opening performance of the safety valve (not shown), a material that is softer and more easily deformed than the current collector terminal 4 is used. The case 1 is not limited to the shape described above.

[0026] Furthermore, thin-walled portions 111T are formed only on the inner walls of the short sides of the opening 111 of the housing body 11. Therefore, both ends 12R of the sealing member 12 in the longitudinal direction (X direction) are supported by stepped portions 111S formed at the lower ends of the thin-walled portions 111T. However, the opening 111 of the housing body 11 lacks thin-walled portions on the inner walls of the long sides, resulting in a structure that cannot prevent the central portion of the sealing member 12 from displacing (warping) in the vertical direction (Z direction). Furthermore, the upper surface 121 of the housing 1 (sealing member 12) has a sensor contact surface 12S configured to contact the temperature sensor 5 that monitors the battery temperature.

[0027] The electrode assembly 2 is composed of a stacked positive electrode assembly 21 and a negative electrode assembly 22 with a separator 23 interposed therebetween, and is housed within the outer casing 1. The positive electrode assembly 21 and the negative electrode assembly 22 each have active material-uncoated portions 211 and 221, respectively, where the active material KT1 and KT2 are not applied to one end portion 21K1 and 22K1 of the electrode foil 21K and 22K; and active material-coated portions 212 and 222, respectively, where the active material KT1 and KT2 are applied to the electrode foil 21K and 22K. The active material-uncoated portion 211 of the positive electrode assembly 21 and the active material-uncoated portion 221 of the negative electrode assembly 22 are located on opposite sides of the sealing body 12 in the longitudinal direction (X direction). The active material-coated portions 212 and 222 are formed on the other end portions 21K2 and 22K2 and the intermediate portions 21K3 and 22K3 of the electrode foil 21K and 22K. Here, the electrode assembly 2 is formed by stacking the positive electrode assembly 21 and the negative electrode assembly 22 with the separator 23 interposed therebetween and winding the stacked components into a flat shape. However, the sheet-shaped positive electrode assembly 21 and the negative electrode assembly 22 may be stacked into a flat shape with the separator 23 interposed therebetween.

[0028] The present electrical storage device 10 refers to any electrical storage device capable of extracting electrical energy, including, for example, primary batteries, secondary batteries, and electric double layer capacitors. For example, in a lithium-ion secondary battery, the electrode foil 21K of the positive electrode 21 is made of, for example, aluminum foil, and the active material KT1 coated on the electrode foil 21K is made of, for example, lithium transition metal oxide (LiNi 1 / 3 Co 1 / 3 Mn1 / 3O2, LiNiO2, etc.). Furthermore, the electrode foil 22K of the negative electrode body 22 is made of, for example, copper foil, and the active material KT2 coated on the electrode foil 22K can be made of, for example, graphite, hard carbon, soft carbon, etc. Furthermore, the separator 23 can be made of, for example, a porous sheet such as polypropylene or polyethylene. Furthermore, a known non-aqueous electrolyte can be used as the electrolyte.

[0029] In addition, among the collector terminals 4, the collector terminal 4A of the positive electrode is made of aluminum, for example, and the collector terminal 4B of the negative electrode is made of copper, for example. The positive and negative collector terminals 4 (4A, 4B) respectively have an integrally formed base portion 41, a base adjacent portion 42, and a lead portion 43. In addition, the base portion 41 allows the insulating component 3 to be interposed and combined with the back side of the two end portions 12R of the sealing body 12 in the long side direction (X direction). In addition, the base adjacent portion 42 is adjacent to the base portion 41 and is detachably abutted against the insulating component 3. At the position of the upper end portion 43a of the lead above the shell, the lead portion 43 is bent from the base adjacent portion 42 toward the lower direction of the shell (Z direction), and the electrode foils 21K, 22K of the active material non-coated portions 211, 221 of the electrode body 2 are welded to the lower end portion 43b of the lead below the shell in an overlapping state (foil collection state).

[0030] Furthermore, the base portion 41 is connected to the external connection portion 45 located on the surface side of the sealing body 12 by, for example, a rivet pin 46 or the like. An insulating member 3, also serving as a sealant, is sandwiched between the rivet pin 46 and the external connection portion 45 and the sealing body 12. For example, polyphenylene sulfide (PPS) resin can be used for the insulating member 3. When connecting multiple electrical storage devices 10, a bus bar (not shown) is connected to the external connection portion 45 for connection.

[0031] Furthermore, when welding the electrode body 2 to the lead lower end portion 43b, external forces tend to be generated that displace the lead lower end portion 43b in the longitudinal direction (X direction) of the sealing body 12 due to, for example, the sliding of the lead lower end portion 43b relative to the electrode foils 21K and 22K in the middle of the foil collection. By reducing this external force, warping deformation of the sealing body 12 (housing 1) that causes the longitudinal center portion of the sealing body 12 (housing 1) to displace in the vertical direction (Z direction) between the base portion 41 and the longitudinal end portions 12R can be effectively suppressed. As a result, the temperature sensor 5 can accurately contact the sensor contact surface 12S formed on the upper surface 121 of the sealing body 12 (housing 1), thereby improving the measurement accuracy of the temperature sensor 5.

[0032] Hereinafter, a method for manufacturing the electrical storage device 10 will be described that can reduce the external force that displaces the lead lower end 43 b in the longitudinal direction (X direction) of the sealing body 12 (casing 1 ) when welding the electrode body 2 to the lead lower end 43 b .

[0033] <Method for manufacturing the present electricity storage device>

[0034] Next, a method for manufacturing the electrical storage device 10 according to the embodiment of the disclosed technology will be described in detail with reference to the accompanying drawings. Figure 4 Shown in Figure 1 The enlarged cross-sectional view of part B is shown. Figure 5 Shown in the Figure 1 Flowchart of the method for manufacturing an electric storage device shown in FIG. Figure 6A In, use Figure 4 The CC cross section shown shows Figure 5 Schematic cross-sectional view of the stacked state of the electrode assembly before the preliminary bending step.

[0035] like Figure 5 As shown, the manufacturing method of the present electrical storage device 10 comprises a preliminary bending step S1 and a collector terminal joining step S2. Figure 6AAs shown, for the electrode body 2 before the preliminary bending step S1, the electrode main body 2H in which the separator 23, the active material coating portion 222 of the negative electrode body 22, the separator 23 and the active material coating portion 212 of the positive electrode body 21 are sequentially stacked, and the electrode body end 2T in which the active material non-coating portion 221 of the negative electrode body 22 is sequentially stacked with a gap is formed into a straight line. In addition, the electrode body end 2T of the negative electrode body 22 and the electrode body end 2T of the positive electrode body 21 located on the opposite side in the long side direction of the sealing body 12 (housing 1) (not shown) are sequentially stacked with the active material non-coating portion 211 of the positive electrode body 21 with a gap, and are formed into a straight line. The active material non-coating portion 211 is not in the Figures 6A to 6C and Figures 7A to 7C Although not shown in the figure, the active material non-coated portion 221 has the same structure as that of the active material non-coated portion 221 , and therefore, the active material non-coated portion will be described below using reference numerals 211 and 221 .

[0036] In addition, Figure 6B In the figure, it is shown that Figure 6A The active material non-coated portion shown is a schematic cross-sectional view of a state where the active material non-coated portion is bent and overlapped to form a fold at the boundary with the active material coated portion. Figure 6C Release from overlapping state Figure 6B Schematic cross-sectional view of the active material non-coated portion shown.

[0037] In the preliminary bending step S1, Figure 6B As shown, the active material non-coated portions 211 and 221 are bent into an overlapping state (KS) using a pressing jig 6, and a fold QP is formed on the active material non-coated portions 211 and 221 at the boundary KR with the active material coated portions 212 and 222. Figure 6C As shown, the active material-uncoated portions 211 and 221 are released. The pressing jig 6 has flat pressing surfaces 61 and 62 and vertical wall surfaces 63 and 64, and includes an upper pressing tool 6A and a lower pressing tool 6B. The upper pressing tool 6A and the lower pressing tool 6B pinch and press the active material-uncoated portions 211 and 221 from above and below. The corners R1 and R2 of the upper pressing tool 6A and the lower pressing tool 6B form folds QP in the active material-uncoated portions 211 and 221 at the boundaries KR with the active material-coated portions 212 and 222.

[0038] In addition, the intersection angles θ1 and θ2 of the corners R1 and R2 of the extrusion surfaces 61 and 62 and the longitudinal wall surfaces 63 and 64 can be formed as right angles, but can also be formed as acute angles (for example, greater than 80 degrees and less than 90 degrees). This is because by forming the intersection angles θ1 and θ2 of the corners R1 and R2 into acute angles, the corners R1 and R2 abut against the active material non-coated portions 211 and 221 of the boundary portion KR in a manner that can form a larger curve, making it easier to form a fold QP. In addition, when the corners R1 and R2 of the upper extrusion tool 6A and the lower extrusion tool 6B are formed into an arc shape, the arc radius is preferably less than 1 mm, and more preferably about 0.4 to 0.6 mm. This is because if the arc radius is greater than 1 mm, the electrode foils 21K and 22K of the bent active material non-coated portions 211 and 221 will rebound, and it may be impossible to fully form the fold QP. Furthermore, it is preferable that the gap D1 between the pressing surfaces 61 and 62 when the upper pressing tool 6A and the lower pressing tool 6B vertically clamp the active material non-coated portions 211 and 221 is slightly larger (e.g., approximately 0.1 to 0.3 mm) than the total thickness D2 of the active material non-coated portions 211 and 221. This is to prevent the electrode foils 21K and 22K from being strongly pulled and broken when the upper pressing tool 6A and the lower pressing tool 6B vertically clamp the active material non-coated portions 211 and 221.

[0039] In addition, after the fold QP is formed in the active material non-coated portion 211, 221 at the boundary KR with the active material coated portion 212, 222, as shown in FIG. Figure 6C As shown, the active material non-coated portions 211 and 221 are released. By temporarily releasing the bent active material non-coated portions 211 and 221, the active material non-coated portions 211 and 221 attempt to restore themselves due to elastic force. This reduces the tensile residual stress in the electrode foils 21K and 22K within the active material non-coated portions 211 and 221, making it less likely that the electrode foils 21K and 22K will break during the subsequent collector terminal joining step S2. Furthermore, the active material non-coated portions 211 and 221 in the released state (KH) rebound in an attempt to return to their original state, but a fold QP remains at the boundary KR to a certain extent. In particular, the fold QP remains significantly larger in the stacked active material non-coated portions 211 and 221 above and below.

[0040] In addition, Figure 7A Shown in Figure 6C A schematic cross-sectional view of a current collecting terminal provided on the active material non-coated portion shown in FIG. Figure 7B shown in the Figure 7A The active material non-coated portion shown is a schematic cross-sectional view of the current collector terminal being joined after being bent again into an overlapping state. Figure 7C shown in the Figure 7BSchematic cross-sectional view showing a state where the active material non-coated portion and the current collector terminal are completely joined.

[0041] In the collector terminal joining step S2, after the preliminary bending step S1, Figure 7A As shown, the lead portion 43 (lead lower end portion 43b) of the collector terminal 4 is brought into contact with the active material non-coated portions 211 and 221 in the released state (KH) with the fold QP remaining at the boundary KR. Figure 7B As shown, the active material non-coated portions 211 and 221 are bent again into an overlapping state using a bonding tool 7, thereby bonding them to the lead lower end portion 43b. The bonding tool 7 includes, for example, an upper pressing tool 7A and a lower pressing tool 7B, each having pressing surfaces 71 and 72 capable of resistance welding or ultrasonic welding. The upper and lower pressing tools 7A and 7B are clamped from above and below, pressing the lead lower end portion 43b and the active material non-coated portions 211 and 221 in an overlapping state (KS), while applying electricity or ultrasonic vibrations. This welds the active material non-coated portions 211 and 221 to the lead portion 43 (lead lower end portion 43b).

[0042] Here, folds QP remain at the boundaries KR between the active material-uncoated portions 211 and 221 and the active material-coated portions 212 and 222. Therefore, when the upper and lower press tools 7A and 7B bend the active material-uncoated portions 211 and 221 again into the overlapping state (KS), the active material-uncoated portions 211 and 221 can be simply bent starting from the folds QP. This reduces the risk of breakage of the active material-uncoated portions 211 and 221 and reduces the external force that displaces the lower lead end portion 43b in the longitudinal direction (X direction) of the housing. By reducing this external force, the amount Q of vertical displacement (Z direction) of the longitudinal center portion of the sealing member 12 (housing 1), to which the base portion 41 is coupled at both longitudinal end portions 12R, can be reduced, thereby improving the measurement accuracy of the temperature sensor 5 that monitors the battery temperature. Furthermore, since the folds QP of the active material non-coated portions 211 and 221 are formed at the boundaries KR with the active material coated portions 212 and 222 , the current collector terminal 4 can be joined near the boundaries KR with the active material coated portions 212 and 222 , thereby increasing the storage capacity per unit volume of the housing.

[0043] Therefore, according to the manufacturing method of the present electrical storage device 10, a manufacturing method of the electrical storage device 10 can be provided, which can increase the electrical storage capacity per unit volume of the casing, reduce the positional deviation of the collector terminal 4 when the electrode foils 21K and 22K are joined to the collector terminal 4, and thereby suppress the warping deformation of the casing 1 to which the collector terminal 4 is joined.

[0044] In the method for manufacturing the electrical storage device 10, it is preferable to Figure 5In the preliminary bending step S1 shown, the active material-uncoated portions 211 and 221 are bent multiple times into an overlapping state (KS). By bending the active material-uncoated portions 211 and 221 multiple times, the fold QP formed at the boundary KR with the active material-coated portions 212 and 222 can be more stably retained. This further reduces the external force that displaces the lead lower end portion 43b in the longitudinal direction (X direction) of the housing during the current collector terminal joining step S2, and also reduces breakage of the active material-uncoated portions 211 and 221. Consequently, the amount Q of vertical displacement (Z direction) of the longitudinal center portion of the sealing body 12 (housing 1), to which the base portion 41 is bonded at both longitudinal end portions 12R, can be reduced, further improving the measurement accuracy of the temperature sensor 5 that monitors the battery temperature.

[0045] Furthermore, in the preliminary bending step S1, when the active material non-coated portions 211 and 221 are bent multiple times into the overlapping state (KS), the gap D1 between the pressurizing surfaces 71 and 72 is gradually narrowed to gradually increase the bending angle of the active material non-coated portions 211 and 221. In this case, local extension of the electrode foils 21K and 22K in the active material non-coated portions 211 and 221 can be reduced, further preventing breakage.

[0046] exist Figure 8 2 shows a schematic cross-sectional view of a state in which, in a method for manufacturing an electrical storage device 10B according to a comparative example, a joining tool 7 is pressing both the current collector terminal 4 and the active material non-coated portions 211 and 221 to overlap the active material non-coated portions 211 and 221 and join the current collector terminal 4. In the method for manufacturing the electrical storage device 10B according to this comparative example, the lead lower end portion 43b of the current collector terminal 4 easily slides in the longitudinal direction (X direction) of the sealing body 12 (casing 1) relative to the bent active material non-coated portions 211 and 221, thereby increasing the amount of positional deviation of the lead lower end portion 43b, which is undesirable.

[0047] Modifications

[0048] The embodiments described in detail above are merely illustrative and in no way limit the disclosed technology. Therefore, various modifications and variations of the disclosed technology are possible without departing from its main purpose. For example, the pressing jig 6 used in the preliminary bending step S1 is different from the bonding tool 7 used in the collector terminal bonding step S2, but this is not limiting. For example, the bonding tool 7 used in the collector terminal bonding step S2 can also serve as the pressing jig 6 used in the preliminary bending step S1.

Claims

1. A method for manufacturing an electric storage device, the electric storage device comprising: shell; an electrode body housed in the housing, formed by laminating a positive electrode body and a negative electrode body with a separator interposed therebetween, the positive electrode body and the negative electrode body having an active material-coated portion in which an active material is coated on electrode foil, and an active material-uncoated portion in which the active material is not coated on one end portion of the electrode foil located on opposite sides of the longitudinal direction of the housing; and The positive and negative current collecting terminals have a base portion connected to both ends of the longitudinal direction of the housing via an insulating member, and a lead portion connected to the active material non-coated portion in an overlapping state. in, The method for manufacturing an electric storage device comprises: a preliminary bending step of bending the active material non-coated portion into an overlapping state, forming a fold in the active material non-coated portion at a boundary with the active material coated portion, and then releasing the active material non-coated portion in the overlapping state; and The current collector terminal joining step is a step of bending the active material non-coated portion again into an overlapping state after the preliminary bending step and then joining the portion to the lead.

2. The method for manufacturing an electric storage device according to claim 1, wherein: In the preliminary bending step, the active material non-coated portion is bent multiple times into an overlapping state.

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