Manufacturing method for power storage device

Abstract

To provide a manufacturing method for a power storage device with improved electrode body containment capacity.SOLUTION: The manufacturing method for a power storage device includes at least a preparation step for preparing a metal plate material 12p including a first portion P1 constituting a first surface of a case and a pair of second portions P2 extending from the first portion P1 and constituting a pair of second surfaces of the case and an encapsulating step for disposing an electrode body 20 on the first portion P1 of the plate material 12p, bending the metal plate material 12p so that the distance between the pair of second portions P2 becomes narrow, and encapsulating the electrode body 20.SELECTED DRAWING: Figure 6A

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an electricity storage device. [Background technology]

[0002] Generally, an electricity storage device includes an electrode assembly and a case that houses the electrode assembly. Japanese Patent No. 4537353 is a prior art document relating to a method for manufacturing an electricity storage device. Japanese Patent No. 4537353 describes a method for manufacturing a prismatic battery by preparing a case body with a U-shaped cross section and an opening on one side, inserting the electrode assembly into the case body through the opening, and then sealing the opening with a sealing plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4537353 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the inventor's findings, the electrode assembly is often formed as large as possible within the range that allows it to be inserted through the opening of the case body, from the viewpoint of improving the volumetric energy density, etc. Therefore, when attempting to insert the electrode assembly through the opening, the outer periphery of the electrode assembly may get caught in the opening, making it difficult to insert. Furthermore, the electrode assembly may come into contact with the opening during insertion, causing wrinkles in the separator of the electrode assembly or misalignment of the electrode plates.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel method for manufacturing an electricity storage device with improved electrode assembly accommodation capacity. [Means for solving the problem]

[0006] The present invention provides a method for manufacturing an electricity storage device, the electricity storage device comprising: one or more electrode assemblies; and a rectangular case that houses the electrode assemblies, the case having at least a first surface, a pair of second surfaces that extend from a pair of edges of the first surface and face each other, and a third surface that faces the first surface. The manufacturing method includes a preparation step of preparing a metal plate that includes at least a first portion that constitutes the first surface of the case and a pair of second portions that extend from the first portion and constitute the pair of second surfaces of the case; and an enclosing step of placing the electrode assemblies on the first portions of the plate and bending the plate so that the distance between the pair of second portions becomes narrow, thereby enclosing the electrode assemblies.

[0007] In the present invention, since the plate material is folded to encase the electrode assembly in the enclosing step, the electrode assembly can be accommodated more easily than in the conventional method of inserting the electrode assembly through an opening on one side of the case body, and as a result, the occurrence of wrinkles in the separator and misalignment of the electrode plates when the electrode assembly is accommodated can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view schematically illustrating an electricity storage device according to one embodiment. [Figure 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a schematic vertical cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a plan view of a plate according to one embodiment. [Figure 5A] FIG. 5A is a side view schematically showing a state during pressing in the second surface pre-molding step. [Figure 5B] FIG. 5B is a side view schematically showing the state after pressing in the second surface pre-forming step. [Figure 6A] FIG. 6A is a side view schematically showing the state when the electrode body is arranged in the enclosing step. [Figure 6B] FIG. 6B is a side view schematically showing a state during pressing in the enclosing step. [Figure 7] FIG. 7 is a side view schematically showing the joining step. [Figure 8] FIG. 8 is a view corresponding to FIG. 3, showing a first modified example in which there is one electrode body. [Figure 9] FIG. 9 is a view corresponding to FIG. 3, showing a second modified example in which there are three electrode bodies. [Figure 10] FIG. 10 is a view corresponding to FIG. 4 according to the third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the technology disclosed herein will be described below with reference to the drawings as appropriate. Matters necessary for implementing the present invention other than those specifically mentioned in this specification (e.g., the general configuration and manufacturing process of an electricity storage device that does not characterize the present invention) can be understood as design matters for a person skilled in the art based on prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field. Furthermore, in the following drawings, components and parts that perform the same function are designated by the same reference numerals, and redundant explanations may be omitted or simplified. Furthermore, in this specification, the notation "A to B" indicating a range is intended to include not only the meaning of A or more and not more than B, but also the meanings of "greater than A" and "smaller than B."

[0010] [Energy storage devices] First, an energy storage device manufactured by the technology disclosed herein will be described. In this specification, the term "energy storage device" refers to a device in general that can be repeatedly charged and discharged, and is a concept that encompasses secondary batteries such as lithium-ion secondary batteries and nickel-metal hydride batteries, and capacitors such as lithium-ion capacitors and electric double layer capacitors.

[0011] FIG. 1 is a perspective view schematically showing an energy storage device 100 according to one embodiment. FIG. 2 is a schematic longitudinal cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a schematic longitudinal cross-sectional view taken along line III-III in FIG. 1. As shown in FIG. 1, the energy storage device 100 has a hexahedral polygonal shape (here, a rectangular parallelepiped shape). In the following description, the symbols F, Rr, L, R, U, and D in the drawings represent front, rear, left, right, top, and bottom, and the symbols X, Y, and Z in the drawings represent the thickness direction, width direction perpendicular to the thickness direction, and up-down direction perpendicular to the thickness direction and width direction, respectively, of the energy storage device 100. However, these directions are merely used for convenience of description and do not limit the installation form of the energy storage device 100 in any way.

[0012] 2, the electricity storage device 100 includes a case 10, one or more (two or more) electrode assemblies 20, a positive electrode terminal 30, and a negative electrode terminal 40. The electricity storage device 100 here further includes a non-aqueous electrolyte (not shown). The electricity storage device 100 here is a non-aqueous electrolyte secondary battery, for example, a lithium ion secondary battery.

[0013] The case 10 is a housing that houses the electrode assembly 20. As shown in FIGS. 1 and 2, the case 10 has a flat, bottomed, angular (here, rectangular parallelepiped) outer shape. The material of the case 10 may be the same as that conventionally used, and is not particularly limited. The case 10 is preferably made of metal, and more preferably made of, for example, iron, iron alloys such as stainless steel, aluminum, aluminum alloys, or the like.

[0014] 2, the case 10 here includes a rectangular cylindrical case body 12 having a pair of openings 12h at both ends in the width direction Y, and two sealing plates 14 that close the pair of openings 12h of the case body 12. The case 10 is integrated by joining (for example, welding) the sealing plates 14 to the peripheries of the pair of openings 12h of the case body 12. The case 10 is hermetically sealed (sealed).

[0015] As shown in FIG. 1 , the case body 12 includes a substantially rectangular bottom surface 12a having long and short sides, a pair of opposing long side surfaces 12b extending from a pair of long sides (a pair of edges) of the bottom surface 12a, and a substantially rectangular top surface 12c facing the bottom surface 12a. The long side surfaces 12b have a larger area than the bottom surface 12a and the top surface 12c. The top surface 12c connects the upper ends of the pair of long side surfaces 12b. In this embodiment, the bottom surface 12a is an example of a "first surface," the pair of long side surfaces 12b are an example of a "pair of second surfaces," and the top surface 12c is an example of a "third surface." However, in other embodiments, for example, the top surface 12c may be the first surface and the bottom surface 12a may be the third surface.

[0016] In this specification, the term "approximately rectangular" refers not only to a perfect rectangular shape (rectangular shape), but also to shapes such as those in which the corners connecting the long and short sides of the rectangle are rounded, or those in which the corners have notches.

[0017] As will be described in detail later, the case body 12 is formed by bending a single plate material 12p (see FIG. 4) into a rectangular tube shape and joining the seams (for example, by welding). In this embodiment, as shown in FIGS. 1 and 3, a joint (preferably a welded joint) 12d formed by joining the seams of the plate material 12p is provided on the top surface 12c of the case body 12. The joint 12d is provided along the front corner of the top surface 12c (the boundary with the front long side surface 12b).

[0018] The sealing plate 14 is a plate-like member that seals the opening 12h. The sealing plate 14 has a substantially rectangular shape in a plan view. As shown in FIGS. 1 and 2, the sealing plate 14 has a liquid inlet 15. The liquid inlet 15 is used to inject the electrolyte into the case 10 after the sealing plate 14 is assembled to the case main body 12. The liquid inlet 15 is sealed with a sealing member 16 after the electrolyte is injected. Note that, although the liquid inlet 15 is provided in the sealing plate 14 in this embodiment, the liquid inlet 15 may be provided in the case main body 12 in other embodiments.

[0019] As shown in Figures 2 and 3, the electrode assembly 20 is housed inside the case 10. The configuration of the electrode assembly 20 may be the same as that of a conventional electrode assembly, and is not particularly limited. The electrode assembly 20 may be housed inside the case 10 while covered with a resin insulating sheet (electrode assembly holder). As shown in Figure 3, here, two (multiple) electrode assemblies 20 are housed inside one case 10. The two electrode assemblies 20 are arranged along the thickness direction (arrangement direction) X. However, the number of electrode assemblies 20 housed inside one case 10 is not particularly limited, and in other embodiments, it may be one, or three or more.

[0020] Here, the electrode assembly 20 is a wound electrode assembly in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked with a strip-shaped separator interposed therebetween and wound in the longitudinal direction around a winding axis. However, in other embodiments, the electrode assembly 20 may be a laminated electrode assembly in which multiple square-shaped (typically rectangular) positive electrodes and multiple square-shaped (typically rectangular) negative electrodes are stacked in an insulated state.

[0021] As shown in FIG. 3, the electrode assembly 20 has a flat outer shape. The electrode assembly 20 has a pair of curved portions 20r and a pair of flat portions 20f connecting the pair of curved portions 20r. In this embodiment, the electrode assembly 20 is disposed inside the case 10 with the winding axis oriented substantially parallel to the width direction Y. Therefore, the pair of curved portions 20r of the electrode assembly 20 face the bottom surface 12a and the top surface 12c of the case body 12, respectively. The pair of flat portions 20f of the electrode assembly 20 face the pair of long side surfaces 12b of the case body 12, respectively. However, in other embodiments, the electrode assembly 20 may be disposed inside the case 10 with the winding axis oriented substantially parallel to the up-down direction Z, for example.

[0022] As shown in Fig. 2, a convex positive electrode tab 23 is attached to the positive electrode of the electrode body 20. The positive electrode tab 23 is electrically connected to the positive electrode terminal 30 via a positive electrode current collector 32. A convex negative electrode tab 24 is attached to the negative electrode of the electrode body 20. The negative electrode tab 24 is electrically connected to the negative electrode terminal 40 via a negative electrode current collector 42.

[0023] The non-aqueous electrolyte is accommodated inside the case 10 together with the electrode assembly 20. The non-aqueous electrolyte may be the same as a conventional one and is not particularly limited. The non-aqueous electrolyte typically contains a non-aqueous solvent and a supporting salt (electrolyte salt, for example, Li salt or Na salt). The non-aqueous electrolyte is typically liquid, but may also be gel-like. In another embodiment, the electricity storage device 100 may include a solid electrolyte instead of the non-aqueous electrolyte. In that case, the separator may be omitted.

[0024] Here, the positive electrode terminal 30 and the negative electrode terminal 40 are fixed to opposing surfaces of the case 10 (specifically, a pair of sealing plates 14). The positive electrode terminal 30 is attached to the sealing plate 14 located on one side in the width direction Y (the right side in FIGS. 1 and 2). The negative electrode terminal 40 is attached to the sealing plate 14 located on the other side in the width direction Y (the left side in FIGS. 1 and 2). In this embodiment, the positive electrode terminal 30 and the negative electrode terminal 40 are provided on the sealing plate 14, but in other embodiments, the positive electrode terminal 30 and the negative electrode terminal 40 may be provided on the case body 12.

[0025] The positive electrode terminal 30 is preferably made of a metal, more preferably aluminum or an aluminum alloy, for example. The negative electrode terminal 40 is preferably made of a metal, more preferably copper or a copper alloy, for example. As shown in FIG. 2, the positive electrode terminal 30 is electrically connected to the positive electrode tab 23 of the electrode assembly 20 via a positive electrode current collector 32 inside the case 10. The negative electrode terminal 40 is electrically connected to the negative electrode tab 24 of the electrode assembly 20 via a negative electrode current collector 42 inside the case 10.

[0026] [Method of manufacturing an electricity storage device] The power storage device 100 can be suitably manufactured by a manufacturing method that typically includes, for example, a preparation step (step S1), a second surface provisional molding step (step S2), an encapsulation step (step S3), a plate material joining step (step S4), and a sealing plate joining step (step S5), in this order. However, the second surface provisional molding step (step S2) is not essential and can be omitted in other embodiments. Furthermore, the manufacturing method of this embodiment may include steps other than those described above at any stage, as appropriate. Each step will be described below.

[0027] The preparation step (step S1) is a step of preparing a metal plate material that constitutes at least a part of the case body 12. FIG. 4 is a plan view of the plate material 12p according to one embodiment. The plate material 12p is preferably made of, for example, iron, an iron alloy such as stainless steel, aluminum, an aluminum alloy, or the like. The plate material 12p here is flat and has a substantially uniform thickness. Although not particularly limited, the thickness of the plate material 12p is preferably approximately 0.1 to 2 mm, more preferably 0.2 to 1 mm, and even more preferably 0.4 to 0.8 mm, from the viewpoint of, for example, mechanical strength, rigidity, and durability. The thickness of the plate material 12p may be the same as or thicker than the thickness of the sealing plate 14.

[0028] As shown in FIG. 4, the plate material 12p here has a substantially rectangular shape. The plate material 12p includes at least a first portion P1 that constitutes the bottom surface 12a (first surface) of the case 10, and a pair of second portions P2 that extend from the first portion P1 and constitute a pair of long side surfaces 12b (a pair of second surfaces) of the case 10. The first portion P1 here has the same shape and size as the bottom surface 12a. The first portion P1 here has a substantially rectangular shape with long sides and short sides. The second portion P2 here has the same shape and size as the long side surfaces 12b. The second portions P2 here extend from the pair of long sides of the first portion P1. Note that the symbols Lx, Ly, and Lz in FIG. 4 respectively represent lengths that correspond to the length in the thickness direction X (thickness), the length in the width direction Y (width), and the length in the up-down direction Z of the external shape of the power storage device 100.

[0029] Preferably, the plate member 12p further includes one or two third portions P3 extending from at least one of the pair of second portions P2 and constituting the top surface 12c (third surface) of the case 10. In FIG. 4, the plate member 12p further includes one third portion P3 extending from one of the second portions P2 and constituting the top surface 12c of the case 10. Here, the third portion P3 has the same shape and size as the top surface 12c. Here, the third portion P3 extends from a long side of one of the second portions P2. The first portion P1, the second portion P2, and the third portion P3 have the same long side length Ly.

[0030] 4, the boundary lines of each part are shown by dashed lines, but these boundary lines are imaginary and indicate the locations to be bent in the second surface provisional forming step (step S2) and / or the encapsulation step (step S3) described later. However, in other embodiments, the boundary lines may be provided with, for example, notches or guides to make it easier to bend the plate material 12p in the second surface provisional forming step (step S2) and / or the encapsulation step (step S3).

[0031] The second surface pre-forming step (step S2) is a step of bending the boundary between the first portion P1 and the second portion P2 of the plate material 12p so that the bending angle is greater than 90°. In this embodiment, the operations from this step to the plate material joining step (step S4) are performed using a manufacturing apparatus 200 (see FIG. 5A, etc.). However, in other embodiments, some or all of the steps may be performed using other devices, or may be performed manually. FIG. 5A is a side view schematically showing the state during pressing in this step. FIG. 5B is a side view schematically showing the state after pressing in this step.

[0032] In this process, first, the plate material 12p prepared in the preparation process (step S1) is placed on the molding stage 210 (see FIG. 5A, etc.) of the manufacturing apparatus 200. Next, as shown in FIG. 5A, a presser plate 120 is placed on the first portion P1 of the plate material 12p, and then the pair of second portions P2 are sandwiched between a pair of side pressure plates 130. The side pressure plates 130 are electrically connected to a control unit (not shown) and are configured to be movable by the control unit between a pressing state shown in FIG. 5A (a state in which the pair of second portions P2 are pressed) and a retracted state shown in FIG. 5B (a state in which the pair of second portions P2 are not pressed). Next, as shown by the arrows in FIG. 5A, the pair of side pressure plates 130 are placed in the pressing state, and a predetermined pressure is applied to the plate material 12p, bending the boundary between the first portion P1 and the second portion P2 so that the pair of second portions P2 approach each other. As a result, the bottom surface 12a (first surface) of the case 10 is defined by the first portion P1.

[0033] 5B, the pair of side pressure plates 130 are retracted, and the retainer plate 120 is removed. In this embodiment, the plate material 12p is bent so that the angle (bending angle) θ1 between the first portion P1 and the second portion P2 is greater than 90°. This prevents interference between the second portion P2 of the plate material 12p and the electrode body 20 in the subsequent packaging step (step S3), thereby further improving the containment ability of the electrode body 20.

[0034] The enclosing step (step S3) is a step of placing one or more electrode bodies 20 on the first portion P1 of the plate material 12p, and folding the plate material 12p so that the distance between the pair of second portions P2 becomes narrow, thereby enclosing the electrode bodies 20. Fig. 6A is a side view schematically showing the state when the electrode bodies are placed in this step. Fig. 6B is a side view schematically showing the state when pressing in this step.

[0035] In this step, first, the electrode assembly 20 is prepared. In this embodiment, the sealing plate 14 is attached to the electrode assembly 20 before the plate joining step (step S4) described later, to form an integrated assembly of the electrode assembly 20 and the sealing plate 14. Specifically, the positive electrode current collector 32 attached to the positive electrode tab 23 of the electrode assembly 20 is joined to the positive electrode terminal 30 fixed to the sealing plate 14, and the negative electrode current collector 42 attached to the negative electrode tab 24 of the electrode assembly 20 is joined to the negative electrode terminal 40 fixed to the sealing plate 14. The joining can be performed by welding, for example, laser welding, ultrasonic welding, resistance welding, or the like. The electrode assembly 20 may be covered with an insulating sheet. In another embodiment, the attachment of the sealing plate 14 may be performed after the plate joining step (step S4). In one example, it may be performed in the sealing plate joining step (step S5).

[0036] Next, as shown by the arrow in FIG. 6A, the electrode assembly 20 is placed on the first portion P1 of the plate material 12p. In this embodiment, an integrated body of the electrode assembly 20 and the sealing plate 14 (not shown in FIG. 6A) is placed on the first portion P1 of the plate material 12p. The electrode assembly 20 (or the integrated body) is entirely housed below the upper end of the second portion P2 of the plate material 12p. As described above, in this embodiment, there are multiple (specifically, two) electrode bodies 20. Each of the multiple electrode bodies 20 is a flat wound electrode body having a pair of curved portions 20r and a pair of flat portions 20f connecting the pair of curved portions 20r. Here, the multiple electrode bodies 20 are placed on the first portion P1 from above the second portion P2 of the plate material 12p. The plurality of electrode bodies 20 are each arranged along the thickness direction (arrangement direction) X so that one curved portion 20r (lower side in FIG. 6A) faces the first portion P1 of the plate material 12p.

[0037] Next, as shown by the arrows in FIG. 6B, the pair of side pressure plates 130 are pressed again, applying a predetermined pressure to the plate material 12p so that the distance between the pair of second portions P2 narrows, bending the boundary between the first portion P1 and the second portion P2. As a result, the angle (bending angle) θ2 between the first portion P1 and the second portion P2 becomes approximately 90°, and the pair of flat portions 20f of the electrode assembly 20 becomes approximately parallel to the second portion P2 of the plate material 12p. In this way, a pair of long side surfaces 12b (a pair of second surfaces) of the case 10 consisting of the pair of second portions P2 are defined. The curved portion 20r and the pair of flat portions 20f on one side of the electrode assembly 20 (the lower side in FIG. 6A) are surrounded from three directions by the first portion P1 and the pair of second portions P2 of the plate material 12p.

[0038] The plate joining step (step S4) is a step of bending the third portion P3 of the plate 12p so as to face the first portion P1 to form the plate 12p into a rectangular tube shape, and joining the seam in a line. In this embodiment, after the plate 12p is formed into a rectangular tube shape, an end E3 (see FIGS. 4 and 6B) of the third portion P3 of the plate 12p is joined to an end E2 (see FIGS. 4 and 6B) of the second portion P2 that abuts the end E3. FIG. 7 is a side view schematically illustrating this step. Note that in this embodiment, the pair of side pressure plates 130 continue to press the pair of second portions P2 (pressing state) from the enclosing step (step S3).

[0039] In this step, as shown in Fig. 7, first, the third portion P3 of the plate material 12p is pressed by the top surface pressure plate 140, and a predetermined pressure is applied to the top surface pressure plate 140 as indicated by the arrow in Fig. 7 to bend the boundary between the second portion P2 and the third portion P3. As a result, the angle (bending angle) between the second portion P2 and the third portion P3 becomes approximately 90°, and the third portion P3 becomes approximately parallel to the first portion P1. In this way, the top surface 12c (third surface) of the case 10 is defined, which is made up of the third portion P3.

[0040] Next, as shown by the circle in FIG. 7, the seams of the plate materials 12p (more specifically, the end E3 of the third portion P3 and the end E2 of the second portion P2 shown in FIGS. 4 and 6B) are joined in a line. The joining method for the plate materials 12p is not particularly limited and may be the same as conventional methods. The joining may be performed by welding such as laser welding, ultrasonic welding, or resistance welding. The joining conditions may also be the same as conventional methods and are not particularly limited.

[0041] In some embodiments, the joining is preferably performed with the pair of second portions P2 of the plate material 12p pressed from both sides. In this embodiment, the pair of second portions P2 of the plate material 12p are sandwiched between a pair of side pressure plates 130 and joined with pressure applied from both sides. This prevents the bending angle between the first portion P1 and the second portion P2 from exceeding 90°, making it easier to maintain the pair of second portions P2 in a substantially parallel state during joining. This improves formability and dimensional accuracy.

[0042] In this embodiment, the third portion P3 of the plate material 12p is further pressed by the top pressure plate 140 during joining. This prevents the bending angle between the second portion P2 and the third portion P3 from exceeding 90°, making it easier to maintain the third portion P3 and the first portion P1 in a substantially parallel state during joining. This improves formability and dimensional accuracy.

[0043] When the electrode assembly 20 is a flat wound electrode assembly, the joining is preferably performed at a position that will become a corner of the case 10 or at a position L / N from the corner (where N is the number of electrode assemblies 20 arranged in the case 10 and is an integer of 2 or greater, and L is the length of the case 10 in the thickness direction (arrangement direction) X of the electrode assembly 20). For example, when the number of electrode assemblies 20 arranged in one case 10 is two (N=2), as in the present embodiment, the joining is preferably performed at a position that will become a corner of the case 10 or at a position L / 2 from the corner in the thickness direction X (i.e., the center in the thickness direction X). This makes it difficult for heat to be transferred during joining to the upper end of the electrode assembly 20, specifically, to the curved portion 20r on the side closer to the third portion P3 (upper side in FIG. 7), thereby suppressing damage to the electrode assembly 20 due to heat.

[0044] In this embodiment, as shown in Fig. 7, welding is performed along the corners of the case 10, specifically along the front corners of the top surface 12c (the boundary between the second portion P2 and the third portion P3). This results in a linear joint 12d as shown in Figs. 1 and 3. In this manner, a rectangular cylindrical case body 12 made of plate material 12p can be obtained.

[0045] The sealing plate joining step (step S5) involves preparing two sealing plates 14 and joining (e.g., welding) the sealing plates 14 to the peripheries of a pair of openings 12h (see FIG. 2) in the case body 12. The sealing plates 14 may be the same as conventional ones and are not particularly limited. The sealing plates 14 are preferably made of metal, and are preferably made of the same metal as the plate material 12p, for example. The joining method for the sealing plates 14 is not particularly limited and may be the same as conventional ones. The sealing plates 14 can be joined by welding, such as laser welding, ultrasonic welding, or resistance welding. After sealing the openings 12h with the sealing plates 14, a nonaqueous electrolyte is typically poured through an injection hole 15 provided in the sealing plates 14 or the like. The injection hole 15 is then closed with a sealing member 16 to hermetically seal the case 10. In this manner, the electricity storage device 100 can be manufactured.

[0046] [Uses of energy storage devices] The electricity storage device 100 can be used for various purposes, and can be suitably used, for example, as a power source (driving power source) for a motor mounted on a vehicle such as a passenger car, a truck, etc. The type of vehicle is not particularly limited, and examples thereof include a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), and a battery electric vehicle (BEV).

[0047] Although the preferred embodiment of the present invention has been described above, the above embodiment is merely an example. The present invention can be implemented in various other forms. The present invention can be implemented based on the contents disclosed in this specification and the technical common sense in the relevant field. The technology described in the claims includes various modifications and alterations of the above-exemplified embodiment. For example, it is possible to replace part of the above-described embodiment with other modifications, or to add other modifications to the above-described embodiment. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate.

[0048] For example, the above-described manufacturing method may further include a third surface pre-forming step of bending the boundary between the second portion P2 and the third portion P3 of the plate material 12p after the preparation step (step S1) and before the encapsulation step (step S3). In this case, it is preferable not to include the second surface pre-forming step (step S2) from the viewpoint of preventing interference between the bent third portion P3 and the electrode body 20 in the encapsulation step (step S3).

[0049] For example, the manufacturing method described above includes a second surface pre-forming step (step S2) before the encapsulation step (step S3), in which the boundary between the first portion P1 and the second portion P2 is bent and pre-shaped. However, this is not limited to this. For example, if a notch or guide is pre-formed at the boundary between the first portion P1 and the second portion P2, the second surface pre-forming step (step S2) may be omitted, and the flat plate material may be directly subjected to the encapsulation step (step S3).

[0050] For example, in the above-described embodiment, the electrode body 20 is a flat wound electrode body, and in the plate joining step (step S4), joining is performed at a position that will become a corner of the case 10 or at a position L / N from the corner. However, this is not limited to this. In a modified example, the electrode body 20 may be a stacked electrode body. In this case, it is preferable to join at a position that will become a corner of the case 10 in the plate joining step (step S4). This makes it difficult for heat to be transferred to the upper end of the electrode body 20 during joining, and prevents damage to the electrode body 20 due to heat.

[0051] For example, in the above-described embodiment, the number of electrode bodies 20 is two, as shown in Fig. 3 etc. However, this is not limited to this. The number of electrode bodies 20 housed inside one case 10 may be one, or three or more.

[0052] FIG. 8 is a diagram corresponding to FIG. 3, showing a first modified example in which there is one electrode body 20. Note that the location of the plate 12p is also shown in parentheses. When there is one electrode body 20 arranged in one case 10, as indicated by the circle in FIG. 8, the joining in the plate joining step (step S4) is preferably performed at a position that will become a corner of the case 10, in this case, a position that will become a front corner A1 or a rear corner A2 of the top surface 12c of the case 10. Also, although the joining is performed at a position that will become the top surface 12c here, the joining may also be performed at a position that will become the bottom surface 12a, for example.

[0053] FIG. 9 is a diagram corresponding to FIG. 3 of a second modified example in which there are three electrode assemblies 20. When the number of electrode assemblies 20 arranged in one case 10 is three (N=3), the joining in the plate joining step (step S4) is preferably performed at a position that will become a corner of the case 10, or at a position L / 3 in the thickness direction X from the corner. Here, as indicated by a circle in FIG. 9, it is preferable to perform the joining at one of the following positions: a position that will become a front corner B1 of the top surface 12c of the case 10, a position that will become a rear corner B2, or positions B3 and B4 that will become L / 3 in the thickness direction X from the corner B1 or B2. Furthermore, although the joining is performed at a position that will become the top surface 12c here, the joining may also be performed at a position that will become the bottom surface 12a, for example.

[0054] For example, the plate material 12p in FIG. 4 described above has one third portion P3, and the third portion P3 has the same shape and size as the top surface 12c. However, this is not limited to this. FIG. 10 is a view corresponding to FIG. 4 according to a third modified example. As shown in FIG. 10, the plate material 12p1 has two third portions P31 and P32. Here, the two third portions P3 extend from the long sides of the pair of second portions P2, respectively. When the two third portions P31 and P32 are joined at their seams, they have the same shape and size as the top surface 12c.

[0055] For example, when the number of electrode bodies 20 arranged in one case 10 is two (N=2), the length in the short side direction of each of the two third portions P31, P32 is Lx / 2. In this modification, in the plate material joining step (step S4), the end E31 of the third portion P31 of the plate material 12p1 is joined to the end E32 of the third portion P32. As a result, the joint is provided in a line shape at the center in the thickness direction X on the top surface 12c of the case body 12, for example.

[0056] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Item 1: A method for manufacturing an electricity storage device comprising one or more electrode bodies and a rectangular case that houses the electrode bodies, the case having at least a first surface, a pair of second surfaces that extend from a pair of edges of the first surface and face each other, and a third surface that faces the first surface, the method comprising: a preparation step of preparing a metal plate that includes at least a first portion that constitutes the first surface of the case and a pair of second portions that extend from the first portion and constitute the pair of second surfaces of the case; and an enclosing step of placing the electrode bodies on the first portion of the plate and bending the plate so that the distance between the pair of second portions becomes narrow, thereby encasing the electrode bodies. Item 2: A method for manufacturing an electricity storage device according to Item 1, wherein the plate material prepared in the preparation step further includes one or two third portions extending from at least one of the pair of second portions and constituting the third surface of the case. Item 3: The method for manufacturing an electricity storage device according to Item 2, further comprising, after the encapsulation step, a plate joining step of bending the third portion of the plate material so as to face the first portion, thereby forming the plate material into a rectangular tube shape, and joining the seams in a line. Item 4: The method for manufacturing an electricity storage device according to Item 3, wherein in the plate joining step, the joining is performed in a state in which the pair of second portions of the plate are pressed from both sides. Item 5: The method for manufacturing an electricity storage device according to Item 3 or 4, wherein there are a plurality of electrode bodies, and each of the plurality of electrode bodies is a flat wound electrode body having a pair of curved portions and a pair of flat portions connecting the pair of curved portions, and in the enclosing step, each of the plurality of wound electrode bodies is arranged along an arrangement direction so that one of the curved portions faces the first portion, and in the plate joining step, the joining is performed at a position that becomes a corner of the case or at a position L / N from the corner (where N is the number of the electrode bodies arranged in the case and is an integer of 2 or more, and L is the length of the case in the arrangement direction of the electrode bodies). Item 6: The method for manufacturing an electricity storage device according to Item 3 or 4, wherein the electrode assembly is a laminated electrode assembly, and in the plate joining step, the joining is performed at positions that will become corners of the case. Item 7: The method for manufacturing an electricity storage device according to any one of items 1 to 6, further comprising, after the preparing step and before the enclosing step, a second surface pre-forming step of bending the boundary between the first portion and the second portion of the plate material so that the bending angle is greater than 90°. Item 8: The method for manufacturing an electricity storage device according to any one of items 1 to 6, further comprising a third surface pre-forming step of bending the boundary between the second portion and the third portion of the plate material after the preparing step and before the enclosing step. [Explanation of symbols]

[0057] 10 cases 12 Case body 12a Bottom (first side) 12b Long side (2nd side) 12c Top (3rd side) 12d joint 14 Sealing plate 20 Electrode body 20f flat area 20r curved section 100 Energy storage device 12p, 12p1 board material P1 Part 1 P2 2nd part P3, P31, P32 3rd part

Claims

1. The device comprises one or more electrode bodies and a rectangular case that houses the electrode bodies, The case has at least a first surface, a pair of second surfaces extending from a pair of edges of the first surface and facing each other, and a third surface facing the first surface. A method for manufacturing an electricity storage device, comprising: a preparation step of preparing a metal plate including at least a first portion constituting the first surface of the case and a pair of second portions extending from the first portion and constituting the pair of second surfaces of the case; an enclosing step of placing the electrode body on the first portion of the plate material and bending the plate material so that the distance between the pair of second portions becomes narrow to enclose the electrode body; Including, A method for manufacturing an electricity storage device.

2. The plate material prepared in the preparing step further includes one or two third portions extending from at least one of the pair of second portions and constituting the third surface of the case. The method for manufacturing the electricity storage device according to claim 1 .

3. After the enclosing step, the third portion of the plate material is bent to face the first portion, thereby forming the plate material into a rectangular tube shape, and a plate material joining step is further included. The method for manufacturing the electricity storage device according to claim 2 .

4. In the plate material joining step, the joining is performed in a state where the pair of second portions of the plate materials are pressed from both sides. The method for manufacturing the electricity storage device according to claim 3 .

5. the electrode body is a plurality of electrode bodies, and each of the plurality of electrode bodies is a flat wound electrode body having a pair of curved portions and a pair of flat portions connecting the pair of curved portions, In the enclosing step, the plurality of wound electrode bodies are each arranged along an arrangement direction such that one of the curved portions faces the first portion, In the plate joining step, the joining is performed at a position that is a corner of the case or a position L / N from the corner (where N is the number of the electrode bodies arranged in the case and is an integer of 2 or more, and L is the length of the case in the arrangement direction of the electrode bodies). The method for manufacturing the electricity storage device according to claim 3 or 4.

6. the electrode body is a laminated electrode body, In the plate joining step, the joining is performed at positions that will become corners of the case. The method for manufacturing the electricity storage device according to claim 3 or 4.

7. After the preparing step and before the enclosing step, a second surface pre-forming step is further included in which a boundary between the first portion and the second portion of the plate material is bent at a bending angle greater than 90°. A method for manufacturing the electricity storage device according to claim 1 .

8. The method further includes a third surface pre-forming step of bending the boundary between the second portion and the third portion of the plate material after the preparing step and before the enclosing step. A method for manufacturing the electricity storage device according to claim 2 .

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