Method for manufacturing power storage device

Abstract

Provided is a method for manufacturing a power storage device capable of suppressing deterioration in the volumetric efficiency of a cell (10). The manufacturing method is a manufacturing method of the unit (10). The cell (10) includes an electrode body and an exterior body in which the electrode body is sealed. The exterior body is formed of a laminated film including at least a resin layer, and has a sealing part formed by welding the periphery of the exterior body. The manufacturing method includes: a heating step (step S11) of heating a bent portion, which is a bent portion of the sealing portion; a bending step (step S12, step S13) in which the sealing part is bent at the bent part; and a cooling step (step S14) for cooling the bent portion. The temperature at which the bent portion is heated in the heating step is a predetermined first temperature that is not less than the glass transition temperature Tg of the resin layer or not less than the melting point Tm of the resin layer. The temperature at which the bent portion is cooled in the cooling step is a predetermined second temperature that is not more than the glass transition temperature Tg or not or the melting point Tm or not.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a manufacturing method of an electrical storage device. BACKGROUND

[0002] In the past, there has been a manufacturing method of a laminate battery including: a first step of bringing a metal round wire into contact with a part of one face of a peripheral portion of an exterior body; and a second step of bending the peripheral portion of the exterior body toward the one face while heating the metal round wire and using the metal round wire as a guide (see, for example, Patent Literature 1). Thus, the exterior body can be bent while suppressing damage to a power generating element caused by heat. Therefore, the laminate battery is reduced in width, so that more laminate batteries can be accommodated in a smaller space. As a result, the volumetric efficiency of the electrical storage device can be improved.

[0003] PRIOR ART DOCUMENTS

[0004] Patent Literature 1: Japanese Patent Application Publication No. 2022-175295 SUMMARY

[0005] According to the manufacturing method of Patent Literature 1, depending on the temperature at the time of heating the peripheral portion of the exterior body and the temperature after the bending step, springback of the bent portion of the laminate occurs. Therefore, there is a concern that the volumetric efficiency of the electrical storage device deteriorates.

[0006] The present disclosure was made to solve the above problem, and aims to provide a manufacturing method of an electrical storage device capable of suppressing deterioration of the volumetric efficiency of the electrical storage device.

[0007] The manufacturing method of the present disclosure is a manufacturing method of an electrical storage device. The electrical storage device includes an electrode body and an exterior body in which the electrode body is enclosed. The exterior body is composed of a laminate film including at least a resin layer, and has a sealing portion in which a peripheral edge of the exterior body is fused. The manufacturing method includes: a heating step of heating a bent portion that is a bent portion of the sealing portion; a bending step of bending the sealing portion at the bent portion; and a cooling step of cooling the bent portion. The temperature at which the bent portion is heated in the heating step is a predetermined first temperature of the glass transition temperature Tg or more or the melting point Tm or more of the resin layer. The temperature at which the bent portion is cooled in the cooling step is a predetermined second temperature of the glass transition temperature Tg or less or the melting point Tm or less.

[0008] According to such a configuration, the bent portion of the sealing portion of the exterior body is bent after being heated at the predetermined first temperature of the glass transition temperature Tg or more or the melting point Tm or more of the resin layer, and is cooled at the predetermined second temperature of the glass transition temperature Tg or less or the melting point Tm or less after being bent. Thus, it is possible to make it difficult for springback of the bent portion to occur. As a result, it is possible to provide a manufacturing method of an electrical storage device capable of suppressing deterioration of the volumetric efficiency of the electrical storage device. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a diagram showing the shape of a unit manufactured by the manufacturing method of the present embodiment.

[0010] Figure 2 is a first diagram for explaining the manufacturing method of the unit of the present embodiment.

[0011] Figure 3 is a second diagram for explaining the manufacturing method of the unit of the present embodiment.

[0012] Explanation of Reference Numerals

[0013] 10 unit, 11 electrode body, 12, 13 laminated film, 14 outer body, 15 sealing portion, 16 bending portion, 100 manufacturing apparatus, 110 control apparatus, 120 heating apparatus, 130 bending apparatus, 131 pressing plate, 132 pressure-attaching portion, 133 inclined surface, 134 clamping surface, 140 cooling apparatus. DETAILED DESCRIPTION

[0014] Hereinafter, the embodiments of the present disclosure will be explained in detail with reference to the drawings. Further, the same or corresponding portions are denoted by the same reference numerals in the drawings, and their explanations will not be repeated.

[0015] Figure 1 is a diagram showing the shape of a unit 10 manufactured by the manufacturing method of the present embodiment. Figure 1 (A) is a plan view of the unit 10. Figure 1 (B) is a sectional view of the A-A section of the unit 10. Referring to Figure 1 , the unit 10 is a secondary battery, and in this embodiment, is a lithium-ion battery. However, it is not limited thereto, and the unit 10 can also be a nickel-hydrogen battery or a full-solid battery. Two or more units 10 are combined to constitute a battery pack.

[0016] The unit 10 includes an electrode body 11 and an outer body 14. Further, the unit 10 includes a positive electrode tab and a negative electrode tab, but they are not illustrated in Figure 1 . The electrode body 11 is housed in the outer body 14. The electrode body 11 has a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators. The positive electrodes and the negative electrodes are alternately laminated. The positive electrode has a positive electrode active material that absorbs lithium (Li) ions. The negative electrode has a negative electrode active material that absorbs lithium ions. The separator is disposed between the positive electrode and the negative electrode. The separator is formed of an insulating material that allows lithium ions to pass therethrough. Further, although not illustrated, in the case of a lithium-ion battery, an electrolyte is enclosed in the inside of the outer body 14 together with the electrode body 11.

[0017] The outer casing 14 is composed of a laminated film 12 on a first side and a laminated film 13 on a second side. The laminated films 12 and 13 have: a metal film substrate (e.g., aluminum foil, stainless steel foil) and resin layers (e.g., polypropylene (PP) layers, biaxially stretched nylon film layers) formed on both sides of the film substrate. The laminated films 12 and 13 are melted by overheating the resin layers at their respective peripheries in the sealing portion 15. That is, the sealing portion 15 is formed at the periphery of the outer casing 14.

[0018] Conventionally, a method for manufacturing a laminated cell 10 includes a first step of abutting a metal wire against a portion of the periphery of an outer casing 14; and a second step of bending the periphery of the outer casing 14 towards one side while heating the metal wire, using the metal wire as a guide. This reduces the width of the laminated cell 10, allowing more laminated cells 10 to be housed in a smaller space. Consequently, the volumetric efficiency of the battery pack, i.e., the energy storage device, composed of multiple cells 10, can be improved. However, depending on the temperature during heating of the periphery of the outer casing 14 and the temperature after the bending process, springback occurs in the bent portion of the laminate. Therefore, there is a concern that the volumetric efficiency of the energy storage device may deteriorate.

[0019] Therefore, the manufacturing method of unit 10 includes: a heating step of heating the bent portion, which serves as the bent portion of the sealing portion 15; a bending step of bending the sealing portion 15 at the bent portion; and a cooling step of cooling the bent portion. In the heating step, the temperature of the bent portion is a predetermined first temperature (e.g., 160°C) that is above the glass transition temperature Tg (e.g., approximately -20°C if the resin is polypropylene) or above the melting point Tm (e.g., approximately 140°C if the resin is polypropylene). In the cooling step, the temperature of the bent portion is a predetermined second temperature (e.g., 100°C) that is below the glass transition temperature Tg or below the melting point Tm.

[0020] Therefore, the bent portion of the sealing portion 15 of the outer casing 14 is heated to a predetermined first temperature above the glass transition temperature Tg or melting point Tm of the resin layers of the laminated films 12 and 13, and then cooled to a predetermined second temperature below the glass transition temperature Tg or melting point Tm. This makes it difficult for the bent portion to spring back. As a result, the deterioration of the volumetric efficiency of the energy storage device can be suppressed.

[0021] Figure 2 This is Figure 1, which illustrates the manufacturing method of unit 10 in this embodiment. Figure 3 This is Figure 2, illustrating the manufacturing method of unit 10 in this embodiment. (Refer to...) Figure 2 and Figure 3 ,like Figure 2As shown in (A), the manufacturing apparatus 100 of unit 10 includes a heating device 120, a bending device 130, a cooling device 140, and a control device 110.

[0022] The control device 110 includes a CPU and a memory. The memory stores programs such as predetermined programs for the manufacturing unit 10 and various data. The CPU executes predetermined processes for the manufacturing unit 10 according to the programs stored in the memory.

[0023] The heating device 120 is controlled by the control device 110, which heats at least one of the laminates 12 and 13 of the sealing portion 15 of the unit 10. Figure 3 (A) The bent portion 16 shown is heated (warmed). Figure 3 As shown in (A), the CPU of the control device 110 controls the heating device 120 to perform the process of heating the bent portion 16 at a predetermined first temperature. Figure 2 (B) Step S11). The predetermined first temperature is a temperature set in advance during the design process that is above the glass transition temperature Tg or the melting point Tm of the resin layer of the laminates 12 and 13. Furthermore, if the film substrate of the laminates 12 and 13 is aluminum, the predetermined first temperature is a temperature lower than the melting point of aluminum (660°C if it is pure aluminum).

[0024] The bending device 130 is controlled by the control device 110, which bends the sealing portion 15 of the bending unit 10 at the bending section 16. For example... Figure 3 (A) to Figure 3 As shown in (B), the CPU of the control device 110 controls the bending device 130 to perform the step of making the pressing plate 131 abut in the process of bending the sealing part 15 in the bending part 16. Figure 2 (Step S12 of (B)). Details of this bending process are described in Japanese Patent Application Publication No. 2019-200973.

[0025] like Figure 3 As shown in (A), the bending device 130 includes a pressing plate 131. Figure 3 In (A), a cross-section of the pressing plate 131 is shown. The length of the pressing plate 131 from the inside of the paper towards the front is greater than the length of the unit 10 in the same direction. The cross-section of the portion of the pressing plate 131 that abuts against the unit 10 in the same direction is... Figure 3 (A) shows the same cross-section shape. In the process of heating the bent portion 16 to a predetermined first temperature and then abutting the pressing plate, as shown... Figure 3 (A) and Figure 3 As shown in (B), the pressing plate 131 moves in the direction indicated by arrow a and comes into contact with the bent portion 16.

[0026] Next, as Figure 3 (C) to Figure 3As shown in (E), the CPU of the control device 110 controls the bending device 130 to perform the process of bending the sealing portion 15 to form the bending portion in the process of bending the sealing portion 15 in the bending portion 16. Figure 2 (B) Step S13).

[0027] like Figure 3 As shown in (C), the bending device 130 further includes a pressing portion 132. Figure 3 (C) shows a cross-section of the pressing portion 132. The pressing portion 132 has an inclined surface 133, which slides relative to the sealing portion 15, and a clamping surface 134. The length of the pressing portion 132 in the direction from the inside of the paper surface toward the front is greater than the length of the unit 10 in the same direction, and is approximately the same length as the length of the pressing plate 131 in the same direction. The cross-section of the portion of the pressing portion 132 that abuts against the unit 10 in the same direction is... Figure 3 (C) shows the same shape as the cross section.

[0028] In the process of forming the bent section, such as Figure 3 As shown in (C), the pressing part 132 moves in the direction indicated by arrow b. Next, as... Figure 3 As shown in (D), the inclined surface 133 slides relative to the sealing portion 15. Consequently, the sealing portion 15 is bent at the bending portion 16. Then, as... Figure 3 As shown in (E), the pressing part 132 moves in the direction of arrow c, thereby clamping the sealing part 15 between the clamping surface 134 and the pressing plate 131. As a result, the sealing part 15 is bent to a state that is approximately right angle (90 degrees) to the lower surface of the unit 10 (the outer surface of the laminate 13).

[0029] The cooling device 140 is controlled by the control device 110, and cools at least one of the laminates 12 and 13 of the sealing portion 15 of the unit 10. Figure 3 (E) shows the cooling of the bent portion 16. For example... Figure 2 As shown in (E), the CPU of the control device 110 controls the heating device 120 to perform a process of cooling the bent portion 16 at a predetermined second temperature. Figure 2 (B) Step S14). The predetermined second temperature is a temperature pre-set during design that is below the glass transition temperature Tg or the melting point Tm of the resin layer of the laminates 12 and 13.

[0030] Without heating and cooling processes, after bending the bending portion 16 to 90 degrees, a springback of 15 degrees occurs, resulting in a final bending angle of 75 degrees. On the other hand, with heating and cooling processes as disclosed herein, after bending the bending portion 16 to 90 degrees, a springback of 5 degrees occurs, resulting in a final bending angle of 85 degrees. Thus, according to this disclosure, springback of the bending portion 16 is difficult to occur.

[0031] [Variation Example]

[0032] (1) In the above-described embodiments, such as Figure 3 As shown in (A), unit 10 is depicted as being sequentially transferred between the devices. However, this is not a limitation; unit 10 may also remain stationary, with each device performing a predetermined process.

[0033] (2) Figure 1 As shown in (E), the state in which the bent portion 16 of the sealing portion 15 is cooled by the cooling device 140 can be either the state in which the sealing portion 15 is clamped between the clamping surface 134 of the pressing portion 132 and the pressing plate 131, or the state in which it is not clamped between the clamping surface 134 and the pressing plate 131.

[0034] (3) In the above embodiment, the welding process of forming the sealing portion 15 by welding the laminated films 12 and 13 is performed independently of the aforementioned heating process. However, it is not limited to this, and the heating process may also be performed together with the welding process.

[0035] [Summarize]

[0036] The manufacturing method disclosed herein is the manufacturing method of unit 10. For example... Figure 1 As shown, unit 10 includes an electrode body 11 and an outer casing 14 encapsulating the electrode body 11. (As...) Figure 2 As shown, the outer casing 14 is composed of laminated films 12 and 13, each containing at least a resin layer, and has a sealing portion 15 formed by welding the periphery of the outer casing 14. Figure 3 and Figure 2 As shown, the manufacturing method includes: a heating step (step S11) of heating the bent portion 16, which is a bent portion of the sealing portion 15; a bending step (steps S12 and S13) of bending the sealing portion 15 in the bent portion 16; and a cooling step (step S14) of cooling the bent portion 16. Figure 2 As shown, the temperature at which the bent portion 16 is heated during the heating process is a predetermined first temperature that is above the glass transition temperature Tg or the melting point Tm of the resin layer. For example... ​ As shown, the temperature at which the bent portion 16 is cooled during the cooling process is a predetermined second temperature below the glass transition temperature Tg or below the melting point Tm.

[0037] Therefore, the bent portion 16 of the sealing portion 15 of the outer casing 14 is heated to a predetermined first temperature above the glass transition temperature Tg or melting point Tm of the resin layer before being bent, and then cooled to a predetermined second temperature below the glass transition temperature Tg or melting point Tm. This makes it difficult for the bent portion 16 to spring back. As a result, the deterioration of the volumetric efficiency of the unit 10 can be suppressed.

[0038] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of this disclosure is not defined by the description of the above embodiments but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A method for manufacturing an energy storage device, the energy storage device comprising an electrode body and an outer casing encapsulating the electrode body, the outer casing being composed of a laminated film comprising at least a resin layer and having a sealing portion formed by welding the periphery of the outer casing. The manufacturing method includes: A heating process that heats the bent portion of the bent portion that serves as the sealing portion. The bending process of bending the sealing portion at the bending portion; and A cooling process for cooling the bent portion. The temperature at which the bent portion is heated in the heating process is a predetermined first temperature that is above the glass transition temperature Tg or the melting point Tm of the resin layer. The temperature at which the bent portion is cooled in the cooling process is a predetermined second temperature below the glass transition temperature Tg or below the melting point Tm.

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