Method for manufacturing an electrical storage device

Abstract

Provided is a method for manufacturing an electricity storage device that is less likely to retain gas in an electrode body and that is less likely to retain gas in the electrode body even when gas is generated during use. The method for manufacturing an electricity storage device (1) includes a compression deformation step (S11) in which a housing side wall portion of the electricity storage device (1) that has completed initial charging and aging before permanent sealing is pressed toward an electrode body (20) side, the electrode body (20) is compressed, and at least one of the housing side wall portions (10c, 10d) is plastically deformed so that the electrode body (20) is continuously pressed by the housing side wall portion even after the pressing is released. The method further includes a permanent sealing step (S12) in which the electricity storage device (1) in a state in which the inside of the housing (10) communicates with the outside is permanently sealed airtight, and a pressing release step (S13) in which the pressing in the compression deformation step (S11) is released.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an energy storage device in which the electrode body and electrolyte are housed within a housing. Background Technology

[0002] A known method for manufacturing a battery that houses flat electrodes and electrolyte within a flat, cubic, box-shaped casing includes the following: The battery is assembled with the electrodes housed within the casing, and then electrolyte is injected into the casing. Next, the battery is clamped in the thickness direction using an external compression tool and compressed in that direction. This compresses the electrodes within the battery in the thickness direction, causing plastic deformation of a pair of casing sidewalls that concave towards the electrode side. Then, while maintaining the compression of the battery by the compression tool, the casing is hermetically sealed. The battery is then initially charged, and subsequently aged to complete the battery manufacturing process. Patent Document 1 is an example of prior art related to this manufacturing method.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2013-093122

[0004] However, during the initial charging and aging of the battery, some of the electrolyte decomposes within the electrode body, generating gas. In the manufacturing method described above, initial charging and aging are performed after the casing is plastically deformed and sealed, thus failing to adequately expel the gas generated within the electrode body during initial charging and aging. Furthermore, the gas that should have been expelled from the electrode body does not escape from the casing and remains trapped inside. Therefore, in a battery that has undergone initial charging, the internal pressure increases, and the force exerted on the electrode body by the sidewalls of the casing weakens. If gas is generated within the electrode body during use after the battery leaves the factory, this gas tends to remain trapped within the electrode body. Summary of the Invention

[0005] The present invention was made in view of the current situation, and provides a method for manufacturing an energy storage device that can produce an energy storage device with less gas retained in the electrode body of the completed energy storage device, and even if gas is generated in the electrode body during the use of the energy storage device, the gas is not easily retained in the electrode body.

[0006] One aspect (1) of the present invention for solving the above-mentioned problems is a method for manufacturing an energy storage device, the energy storage device comprising: an electrode body having a pair of electrode body planes, and electrode plates stacked in a thickness direction orthogonal to the extension direction of the electrode body planes; an electrolyte; and a housing having a pair of housing sidewall portions respectively opposite to the pair of electrode body planes, and housing the electrode body and the electrolyte, wherein the method for manufacturing the energy storage device includes a compression deformation step, in which the pair of electrode body planes in the housing of the energy storage device before permanent sealing after initial charging and aging are compressed. The outer casing sidewalls are pressed toward the electrode body, compressing the electrode body between the pair of outer casing sidewalls in the thickness direction, and causing at least one of the pair of outer casing sidewalls to plastically deform and recess toward the electrode body, so that after the compression is released, the electrode body is continuously compressed by the pair of outer casing sidewalls in the thickness direction. After the compression deformation process, the device includes: a permanent sealing process to permanently seal the outer casing of the energy storage device, which is in a state of communication between the inner and outer casings; and a compression release process to release the compression of the energy storage device in the compression deformation process.

[0007] In the above manufacturing method, a compression deformation process is performed on a storage device that has completed initial charging and aging but has not been permanently sealed. Subsequently, while maintaining the compression state of the storage device from the compression deformation process, or while releasing the compression from the compression deformation process through a release process but with the electrode body being squeezed (hereinafter also referred to as "self-squeezing") by the outer casing (a pair of outer casing sidewalls), the outer casing of the storage device, which is in communication with the outside, is sealed so that the seal cannot be removed; that is, a permanent seal is performed (permanent sealing process). Therefore, it is possible to permanently seal the outer casing hermetically while expelling the gas generated during the initial charging and aging process by the decomposition of electrolyte within the electrode body through extrusion to the outside of the electrode body. This allows for the manufacture of a storage device with less gas retention within the electrode body. Furthermore, the completed storage device continuously self-squeezes the electrode body from the outer casing, so even if gas is generated within the electrode body during use of the storage device after leaving the factory, it is easily expelled to the outside of the electrode body through compression, thus preventing gas retention within the electrode body.

[0008] In addition, as "energy storage devices", examples include secondary batteries such as lithium-ion rechargeable batteries and capacitors such as lithium-ion capacitors.

[0009] As an "electrode body having electrode plates stacked in the thickness direction," examples include, for instance, a wound electrode body in which strip-shaped electrode plates are wound into a flat shape and stacked in the thickness direction with electrode plates separated by strip-shaped spacers, and a stacked electrode body in which multiple single-piece electrode plates are stacked in the thickness direction with spacers between them. Furthermore, the energy storage device may have an odd number or multiple electrode bodies.

[0010] The "compression deformation process" can be performed on energy storage devices in a state where the inside and outside of the casing are in contact (unsealed), or on energy storage devices with the casing pre-sealed. Furthermore, the compression deformation process can be performed on energy storage devices that have completed initial charging and aging, as described above. However, when the initial charging process of the energy storage device is divided into multiple stages, it is particularly preferable to perform the compression deformation process on the energy storage device that has completed all initial charges. Additionally, when the energy storage device undergoes multiple aging stages during manufacturing, it is particularly preferable to perform the compression deformation process on the energy storage device that has completed the final aging stage. This is because during subsequent initial charging stages and subsequent aging stages, there is a possibility of electrolyte decomposition within the electrode body, generating gas.

[0011] For the "permanent sealing process" and "extrusion release process" performed after the compression deformation process, the permanent sealing process can be performed first, followed by the extrusion release process, or vice versa. Since the internal pressure may decrease due to the increase in internal volume of the outer shell caused by the elastic aftereffects generated in the electrode body and outer shell during extrusion release, it is preferable to perform the permanent sealing process first, followed by the extrusion release process.

[0012] As a method of "permanent sealing," examples include sealing the connecting hole in the housing by using a sealing component made of metal, or a sealing component with a portion of metal and rubber, and welding the sealing component to the housing to make the seal unremovable. Another example is sealing the connecting hole in the housing by using blind-hole rivets.

[0013] (2) It can also be configured such that, based on the manufacturing method of the energy storage device described in (1), the electrode body has the characteristic that the size in the thickness direction increases with the increase of SOC, so that the energy storage device is in a state of SOC of 30% or less to perform the compression deformation process.

[0014] In the manufacturing method described above, the compression deformation process is performed when the state of charge (SOC) is below 30%, i.e., the thickness dimension of the electrode body is relatively small. Therefore, the sidewall of the outer casing can be sufficiently recessed towards the electrode body. As a result, in the completed energy storage device, the electrode body can be more forcefully self-compressed by the sidewall of the outer casing.

[0015] (3) It can also be configured such that, based on the manufacturing method of the energy storage device described in (1) or (2), the above-mentioned compression deformation process is performed in a state where the inside of the outer casing is connected to the outside.

[0016] In the manufacturing method described above, the compression deformation process is performed while the inside and outside of the outer casing are connected. Therefore, the electrode body can be sufficiently compressed in the thickness direction, thereby allowing the gas generated during initial charging and aging to be more appropriately squeezed out of the electrode body and discharged outside the outer casing. In addition, since the sidewall of the outer casing can be sufficiently recessed towards the electrode body, the electrode body can be more forcefully self-compressed by the sidewall of the outer casing in the completed energy storage device.

[0017] (4) It can also be configured as follows: based on the manufacturing method of the energy storage device described in any one of (1) to (3), the electrode plate of the electrode body is a positive electrode plate and a negative electrode plate having a positive electrode active material layer including positive electrode active material particles, and the positive electrode active material particles are lithium transition metal composite oxide particles having a composition in which Ni accounts for more than 50 mol% of the total amount of transition metals other than Li.

[0018] In electrode bodies having a positive electrode plate using positive electrode active material particles containing a large amount of Ni, there is a tendency for a large amount of gas to be generated during initial charging and aging. However, in the manufacturing method described above, even if a large amount of gas is generated during initial charging and aging, by performing the compression deformation process and the permanent sealing process described above, the generated gas can be extruded from the electrode body to the outside of the electrode body and then discharged to the outside of the casing, and the casing can be permanently sealed. Therefore, it is possible to manufacture an energy storage device having a positive electrode plate using positive electrode active material particles containing a large amount of Ni, and where gas is not easily trapped in the electrode body. Attached Figure Description

[0019] Figure 1 This is a perspective view of the battery involved in the implementation method.

[0020] Figure 2 It is a cross-sectional view along the longitudinal and transverse directions of the battery involved in the embodiment.

[0021] Figure 3 This is a flowchart of the battery manufacturing method involved in the implementation method.

[0022] Figure 4 This is an explanatory diagram illustrating the state of the battery immediately preceding the compression deformation process, as described in the embodiment.

[0023] Figure 5 This is an explanatory diagram illustrating the state of the battery being squeezed during the compression deformation process, as described in the embodiment.

[0024] Explanation of reference numerals in the attached figures

[0025] 1…Battery (energy storage device); 10…Casing; 10c, 10d…Long sidewall of the casing (sidewall of the casing); 10k…Connecting hole; 17…Sealing component; 20…Electrode body; 20a, 20b…Electrode body plane; 21…Positive electrode plate; 21a…Positive active material layer; 21b…Positive active material particles; 22…Negative electrode plate; 23…Separator; 50…Electrolyte; 100…Extrusion device; DH…Thickness direction (of the electrode body); EH…Extension direction (of the electrode body plane); S3…First initial charging process; S5…Second initial charging process; S6…First aging process; S7…Third initial charging process; S9…Second aging process; S11…Compression deformation process; S12…Permanent sealing process; S13…Extrusion release process. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 The diagram shows a perspective view of the battery (energy storage device) 1 according to this embodiment. Figure 2 A cross-sectional view of battery 1 is shown. Furthermore, the longitudinal direction AH, transverse direction BH, and thickness direction CH of battery 1 are defined below as follows: Figure 1 and Figure 2 The direction shown will be used for explanation. This battery 1 is a square and sealed lithium-ion secondary battery that is installed in vehicles such as hybrid vehicles, plug-in hybrid vehicles, and electric vehicles.

[0027] Battery 1 comprises a casing 10, an electrode body 20 housed inside the casing 10, and a positive terminal 30 and a negative terminal 40 supported on the casing 10. The electrode body 20 is covered inside the casing 10 by a bag-shaped insulating film 60 that opens towards the longitudinal direction AH1 of the battery. Furthermore, an electrolyte 50 is housed inside the casing 10, a portion of which is immersed in the electrode body 20, and a portion accumulates on the bottom wall 10b of the casing 10. This electrolyte 50 is an electrolyte in which lithium hexafluorophosphate (LiPF6) is dissolved as a supporting salt in a non-aqueous solvent mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC).

[0028] The outer casing 10 is a cubic box-shaped structure made of metal (aluminum in this embodiment), and has a rectangular upper wall 10a, a rectangular bottom wall 10b opposite to it, and a pair of rectangular long sidewalls (outer casing sidewalls) 10c and 10d and a pair of rectangular short sidewalls 10e and 10f connecting them. In the long sidewalls 10c and 10d, the rectangular central portions 10cg and 10dg, which are respectively U-shaped peripheral portions 10cf and 10df, are recessed inward toward the battery thickness direction CHI, i.e., toward the electrode body 20, and are located closer to the inside of the battery than the peripheral portions 10cf and 10df. Moreover, the electrode body 20 is pressed inward toward the thickness direction DH by the central portions 10cg and 10dg of these long sidewalls 10c and 10d.

[0029] The outer casing 10 is composed of a main casing component 11 and a casing cover component 12. The main casing component 11 is located on one side AH1 of the longitudinal direction AH of the battery (in... Figure 1 The bottomed square tube with an opening 11c (located at the top) forms the bottom wall portion 10b, the long side wall portions 10c and 10d, and the short side wall portions 10e and 10f of the outer shell. The outer shell cover component 12 is a rectangular plate welded to close the opening 11c of the outer shell main component 11, forming the upper wall portion 10a of the outer shell.

[0030] A safety valve 15 is provided near the center of the battery's transverse direction BH in the outer casing cover component 12. This safety valve breaks and opens when the internal pressure of the outer casing 10 exceeds the valve opening pressure. Furthermore, a communication hole 10k is formed in the outer casing cover component 12, connecting the inside and outside of the outer casing 10. This hole is permanently and hermetically sealed by a circular plate-shaped sealing member 17 made of metal (aluminum in this embodiment). Specifically, with the communication hole 10k covered from the outside by the sealing member 17, the sealing member 17 is welded to the outer casing 10 (outer casing cover component 12) around its entire circumference. This communication hole 10k is used to inject electrolyte 50 into the outer casing 10.

[0031] Furthermore, a positive terminal 30, composed of multiple aluminum components, is fixedly disposed on the housing cover component 12 in an insulated state. This positive terminal 30 is connected and conductive to the positive electrode plate 20p (described later) of the electrode body 20 within the housing 10, and extends through the housing cover component 12 to the outside of the housing 10. Additionally, a negative terminal 40, composed of multiple copper components, is fixedly disposed on the housing cover component 12 in an insulated state. This negative terminal 40 is connected and conductive to the negative electrode plate 20q (described later) of the electrode body 20 within the housing 10, and extends through the housing cover component 12 to the outside of the housing 10.

[0032] The electrode body 20 is a flat cuboid, consisting of multiple rectangular positive electrode plates (electrode plates) 21 and multiple rectangular negative electrode plates (electrode plates) 22 alternately stacked in the thickness direction DH, separated by a rectangular separator 23 made of a porous resin membrane. The positive electrode plates 21 and the separator 23, which overlap in the thickness direction DH, are bonded together using an adhesive, thereby integrating the electrode body 20 into one unit.

[0033] The electrode body 20 is composed of six planes. Specifically, the electrode body 20 has a pair of electrode planes 20a and 20b extending in an extension direction EH orthogonal to the thickness direction DH, and four peripheral electrode planes 20c, 20d, 20e, and 20f connecting these planes. Furthermore, in the battery 1, the electrode plane 20a of the electrode body 20 faces the long sidewall portion 10c of the outer casing 10, and the electrode plane 20b faces the long sidewall portion 10d of the outer casing. Additionally, the peripheral electrode plane 20c faces the upper wall portion 10a of the outer casing, and the peripheral electrode plane 20d faces the bottom wall portion 10b of the outer casing. Furthermore, the peripheral electrode plane 20e faces the short sidewall portion 10e of the outer casing, and the peripheral electrode plane 20f faces the short sidewall portion 10f of the outer casing.

[0034] The positive electrode plate 21 has positive electrode active material layers 21a on each of the two main surfaces of a positive electrode current collector foil (not shown) made of rectangular aluminum foil. The positive electrode active material layers 21a are composed of positive electrode active material particles 21b capable of adsorbing and releasing lithium ions, conductive particles, and a binder. The positive electrode active material particles 21b are lithium transition metal composite oxide particles containing at least 50 mol% Ni of the total amount of transition metals other than Li. In this embodiment, a lithium nickel cobalt manganese composite oxide is used; specifically, LiNi is used, containing 60 mol% Ni of the total amount of transition metals (Ni, Co, Mn) other than Li. 0.6 Co 0.2 Mn 0.2 O2 particles. The extended protrusion in the positive electrode plate 21, extending towards one side AH1 in the longitudinal direction AH of the battery, lacks a positive electrode active material layer 21a in the thickness direction DH, becoming a positive electrode exposed portion 21r exposed in the thickness direction DH by the positive electrode current collector foil. Each positive electrode exposed portion 21r overlaps with each other in the thickness direction DH to form the aforementioned positive electrode sheet 20p. As described above, this positive electrode sheet 20p is connected to the positive terminal 30.

[0035] The negative electrode plate 22 has negative electrode active material layers (not shown) on both main surfaces of a negative electrode current collector foil (not shown) made of rectangular copper foil. The negative electrode active material layers consist of negative electrode active material particles capable of absorbing and releasing lithium ions, a binder, and a tackifier. In the negative electrode plate 22, the protruding portion extending towards one side AH1 in the longitudinal direction AH of the battery does not have a negative electrode active material layer in the thickness direction DH, becoming the negative electrode exposed portion 22r exposed in the thickness direction DH of the negative electrode current collector foil. Each negative electrode exposed portion 22r overlaps with each other in the thickness direction DH to form the aforementioned negative electrode sheet 20q. As described above, this negative electrode sheet 20q is connected to the negative terminal 40.

[0036] Next, the manufacturing method of the aforementioned battery 1 will be described (see reference). Figure 3 First, in the "battery assembly process" S1, the unfilled battery 1 is assembled. That is, the positive electrode plate 21, the negative electrode plate 22, and the separator 23 are stacked to form the electrode body 20. Next, the positive terminal 30 and the negative terminal 40 are fixedly disposed on the housing cover member 12, and the positive terminal 30 and the negative terminal 40 are respectively welded to the positive electrode plate 20p and the negative electrode plate 20q of the electrode body 20. Then, the electrode body 20 is covered with a bag-shaped insulating film 60. Next, the electrode body 20 covered by the insulating film 60 is inserted into the housing body member 11, and the opening 11c of the housing body member 11 is blocked with the housing cover member 12. Then, the housing body member 11 and the housing cover member 12 are welded together around the entire circumference of the housing cover member 12 to form the housing 10. In this way, the unfilled battery 1 is completed.

[0037] Next, in the "liquid injection process" S2, electrolyte 50 is injected into the casing 10 through the connecting hole 10k. After that, the battery 1 is placed for a specified time, and the electrolyte 50 is allowed to permeate the electrode body 20.

[0038] Next, in the "first initial charging step" S3, the battery 1 is initially charged for the first time. In this embodiment, as described later, the initial charging is performed in three stages. Specifically, the charging device (not shown) is connected to the battery 1, and the battery 1 is charged to 10% SOC by constant current (CC) charging at an ambient temperature of 25°C. At this time, a portion of the electrolyte 50 is decomposed within the electrode body 20 to generate gas GA, such as hydrogen. Most of the gas GA discharged from the electrode body 20 into the casing 10 is discharged to the outside of the casing 10 through the connecting hole 10k. Since the electrode body 20 is not compressed in the thickness direction DH, a portion of the gas GA generated within the electrode body 20 remains within the electrode body 20.

[0039] Next, in the "pre-sealing process" S4, the communicating hole 10k of the outer casing 10 is plugged with a pre-sealing component (not shown) made of rubber plugs to pre-seal the outer casing 10 in an airtight manner. This is to prevent air from entering the outer casing 10 of the battery 1 during the subsequent second initial charging process S5 to second aging process S9.

[0040] Next, in the "Second Initial Charging Step" S5, the battery 1 undergoes a second initial charging. Specifically, a charging device (not shown) is connected to the pre-sealed battery 1, and the battery 1 is charged to 35% SOC using a constant current (CC) at an ambient temperature of 25°C. In this Second Initial Charging Step S5 and the subsequent First Aging Step S6, a portion of the electrolyte 50 is also decomposed within the electrode body 20 to generate gaseous GA, such as hydrogen. However, in these steps, since the casing 10 is pre-sealed, the generated gaseous GA does not escape from the casing 10 but remains inside the casing 10. Furthermore, since the electrode body 20 is not compressed in the thickness direction DH, a portion of the gaseous GA generated within the electrode body 20 remains within the electrode body 20.

[0041] Next, in the "first aging process" S6, the battery 1 with an SOC of 35% is placed in an open terminal state for 12 hours at an ambient temperature of 60°C to age the battery 1 at high temperature.

[0042] Next, in the "Third Initial Charging Step" S7, the battery 1 undergoes a third initial charging. Specifically, a charging / discharging device (not shown) is connected to the battery 1, and the battery 1 is charged to 100% SOC using constant current constant voltage (CCCV) charging at an ambient temperature of 25°C. Afterward, a one-minute pause is allowed. In this Third Initial Charging Step S7 and the Second Aging Step S9 described later, a portion of the electrolyte 50 is also decomposed within the electrode body 20 to generate gas GA, such as hydrogen. However, in these steps, since the casing 10 is pre-sealed, the generated gas GA does not escape from the casing 10 but remains inside the casing 10. Furthermore, since the electrode body 20 is not compressed in the thickness direction DH, a portion of the gas GA generated within the electrode body 20 remains within the electrode body 20.

[0043] Next, in the "discharge process" S8, battery 1 is discharged. Specifically, battery 1 is discharged to 0% SOC by constant current (CC) discharge.

[0044] Next, in the "second aging process" S9, the battery 1 with a SOC of 0% is placed in an open terminal state for 12 hours at an ambient temperature of 60°C to age the battery 1 at high temperature.

[0045] Next, in the "pre-seal removal process" S10, under a nitrogen atmosphere, the pre-seal component (rubber plug, not shown) blocking the communication hole 10k of battery 1 is removed, changing the state where the inside of the outer casing 10 is connected to the outside through the communication hole 10k. As a result, most of the gas GA accumulated inside the outer casing 10 is discharged to the outside of the outer casing 10 through the communication hole 10k. However, the gas GA accumulated inside the electrode body 20 remains inside the electrode body 20.

[0046] Next, the "compression deformation process" S11 is performed. Figure 4 The image shows the state of battery 1 immediately before the compression deformation process S11. Figure 5 The image shows the state of the extruded battery 1 during the compression deformation process S11. Furthermore, in... Figure 4 and Figure 5 In the text, the diagrams of positive end 30, negative end 40, etc., are omitted and simplified.

[0047] In the compression deformation process S11, the extrusion device 100 compresses a pair of long sidewall portions 10c and 10d of the unsealed outer casing 10 of the battery 1 towards the electrode body 20. This compresses the electrode body 20 between the pair of long sidewall portions 10c and 10d towards the inner side DHI in the thickness direction DH, and causes the pair of long sidewall portions 10c and 10d to undergo plastic deformation, causing them to indent towards the inner side CHI (electrode body 20 side) in the thickness direction CH. In this process, the long sidewall portions 10c and 10d are sufficiently plastically deformed towards the electrode body 20, so that even after the compression by the extrusion device 100 is released in the compression release process S13 (described later), the electrode body 20 continues to be compressed towards the inner side DHI in the thickness direction DH by the pair of long sidewall portions 10c and 10d. Furthermore, to prevent air from entering the outer casing 10 of the battery 1, the compression deformation process S11 is performed in a nitrogen atmosphere.

[0048] The extrusion device 100 includes two extrusion members 110 and 120 made of metal and facing each other, and a moving mechanism (not shown) for moving these members in a direction of approaching each other JH1 and a direction of moving away from each other JH2. The opposing extrusion surfaces 110n and 120n in the extrusion members 110 and 120 are smaller than the dimensions of the longitudinal AH and transverse BH of the long sidewall portions 10c and 10d of the battery casing 1, respectively, and are approximately the same size as the dimensions of the longitudinal AH and transverse BH of the electrode planes 20a and 20b of the electrode body 20.

[0049] In the compression deformation process S11, a battery 1 with a state of charge (SOC) of 30% or less (SOC 0% in this embodiment) in the discharge process S8 is first placed between two extrusion members 110 and 120 of the extrusion device 100. Specifically, the battery 1 is arranged such that the long sidewall 10c of the battery 1's casing faces the extrusion surface 110n of the extrusion member 110, and the long sidewall 10d of the battery 1's casing faces the extrusion surface 120n of the extrusion member 120. Next, the two extrusion members 110 and 120 are moved in the direction JH1 that brings them closer together by the moving mechanism (not shown) of the extrusion device 100, so that the extrusion surface 110n of one extrusion member 110 abuts against the long sidewall 10c of the battery 1's casing, and the extrusion surface 120n of the other extrusion member 120 abuts against the long sidewall 10d of the casing, thus clamping the battery 1 between the two extrusion members 110 and 120.

[0050] Furthermore, the two extrusion members 110 and 120 are moved in a direction JH1 toward each other, causing the long sidewalls 10c and 10d of the outer casing to be extruded toward the inner side CHI of the battery thickness direction CH, compressing the electrode body 20 on the inner side DHI of the thickness direction DH. The long sidewalls 10c and 10d are also plastically deformed to be recessed toward the inner side CHI of the battery thickness direction CH, thereby positioning the central portions 10cg and 10dg of the long sidewalls 10c and 10d on the inner side CHI of the battery thickness direction CH. In this embodiment, the extrusion is performed with a force of 200 kPa applied to the long sidewalls 10c and 10d. Therefore, after the extrusion performed by the extrusion device 100 is released in the extrusion release step S13 described later, the electrode body 20 is continuously self-extruded by the pair of long sidewalls 10c and 10d in the thickness direction DH.

[0051] By compressing the electrode body 20 along the thickness direction DH in this process, most of the gas GA accumulated inside the electrode body 20 is forced out of the electrode body 20. Furthermore, most of the gas GA is discharged out of the outer casing 10 through the connecting hole 10k.

[0052] Furthermore, the electrode body 20 of this embodiment has the characteristic that its thickness direction DH increases with the increase of SOC. However, in this embodiment, the compression deformation process S11 is performed after the battery 1 is reduced to 0% SOC. That is, the compression deformation process S11 is performed when the thickness direction DH of the electrode body 20 is small. Therefore, the long sidewall portions 10c and 10d of the outer casing can be sufficiently recessed towards the electrode body 20.

[0053] Furthermore, since the compression deformation process S11 is performed in an unsealed state (with the inside of the outer casing 10 communicating with the outside), the electrode body 20 can be sufficiently compressed in the thickness direction DH, allowing the gas GA to be more appropriately expelled from inside the electrode body 20 to outside, and thus discharged out of the outer casing 10. Additionally, the long sidewalls 10c and 10d of the outer casing can be sufficiently recessed towards the electrode body 20.

[0054] Next, in the "permanent sealing process" S12, the unsealed (internal and external communication state) battery 1 casing 10 is hermetically and permanently sealed. In this embodiment, the permanent sealing process S12 is performed while the battery 1 is being compressed by the compression device 100. Specifically, the communicating hole 10k is covered from the outside by the metal sealing member 17, and the sealing member 17 is welded to the casing 10 around the entire circumference to hermetically and irrevocably seal the sealing member 17 and the casing 10 together.

[0055] Next, in the "compression release process" S13, the compression of the battery 1 by the compression device 100 is released. Specifically, the two compression parts 110 and 120 are moved away from the battery 1 by the moving mechanism (not shown) of the compression device 100 in a moving direction JH2. After that, the battery 1 is removed from the compression device 100. In addition, as described above, the pair of long sidewalls 10c and 10d of the outer casing are plastically deformed, so even after the compression by the compression device 100 is released, the outer casing 10 continues to self-compress the electrode body 20 in the thickness direction DH by the pair of long sidewalls 10c and 10d of the outer casing. Therefore, even if gas GA is generated in the electrode body 20 during the use of the battery 1 after leaving the factory, the gas GA can be easily discharged to the outside of the electrode body 20 by compression, so that the gas GA is not easily retained in the electrode body 20.

[0056] Furthermore, in this embodiment, the permanent sealing process S12 is performed first, followed by the compression release process S13. Therefore, in the completed battery 1, during compression release, an internal pressure decrease occurs, accompanied by an increase in the internal volume of the casing caused by the elastic aftereffects generated in the electrode body 20 and the casing 10. Thus, the battery 1 is completed.

[0057] In the manufacturing method of the energy storage device 1 according to this embodiment, a compression deformation process S11 is performed on the battery 1 that has completed the first initial charging process S3, the second initial charging process S5, the first aging process S6, the third initial charging process S7, and the second aging process S9 but has not been permanently sealed. Thereafter, while maintaining the compressed state of the battery 1 in the compression deformation process S11, the casing 10 of the energy storage device 1, which communicates with the outside, is permanently sealed (permanent sealing process S12). Therefore, the casing 10 can be hermetically and permanently sealed while the gas GA generated in the electrode body 20 during the first initial charging process S3, the second initial charging process S5, the first aging process S6, the third initial charging process S7, and the second aging process S9 is extruded out of the electrode body 20 and discharged out of the casing 10. Thus, a battery 1 with less gas GA retention in the electrode body 20 can be manufactured. Subsequently, the completed battery 1 continuously self-compresses the electrode body 20 using a pair of long sidewalls 10c and 10d of the outer casing. Therefore, even if gas GA is generated inside the electrode body 20 during the use of the battery 1 after leaving the factory, the gas GA can be easily discharged to the outside of the electrode body 20 by compression, so that the gas GA is not easily retained inside the electrode body 20.

[0058] Furthermore, in this embodiment, the compression deformation process S11 is performed when the SOC is below 30% (specifically, 0% SOC) and the thickness direction DH of the electrode body 20 is small. Therefore, the long sidewall portions 10c and 10d of the outer casing can be sufficiently recessed towards the electrode body 20. As a result, in the completed battery 1, the long sidewall portions 10c and 10d of the outer casing can more forcefully self-compress the electrode body 20.

[0059] Furthermore, by performing the compression deformation process S11 while the casing 10 is in communication with the outside, the electrode body 20 can be sufficiently compressed in the thickness direction DH, thereby allowing the gas GA to be more appropriately extruded from inside the electrode body 20 to outside the casing 10 and discharged outside the casing 10. Additionally, the long sidewalls 10c and 10d of the casing can be sufficiently recessed towards the electrode body 20, so in the completed battery 1, the long sidewalls 10c and 10d of the casing can more forcefully self-compress the electrode body 20.

[0060] Furthermore, in the electrode body 20 with the positive electrode plate 21, there is a tendency to generate a large amount of gaseous GA. The positive electrode plate 21 uses lithium transition metal composite oxide particles 21b, which are composed of Ni comprising 50 mol% or more of the total amount of transition metals other than Li. However, even if a large amount of gaseous GA is generated, by performing the compression deformation process S11 and the permanent sealing process S12 described above, the gaseous GA can be discharged from inside the electrode body 20 to outside the electrode body 20 and then to outside the casing 10, and the casing 10 can be permanently sealed. Therefore, it is possible to manufacture a battery 1 that has a positive electrode plate 21 using positive electrode active material particles 21b containing a large amount of Ni, and where gaseous GA is not easily retained in the electrode body 20.

[0061] The present invention has been described above according to the embodiments, but the present invention is not limited to the embodiments. It goes without saying that the invention can be applied in a suitable manner without departing from its spirit.

[0062] For example, in one embodiment, a pre-sealing process S4 is performed after the first initial charging process S3, and a pre-sealing release process S10 is performed after the second aging process S9. However, it is also possible to perform the second initial charging process S5 to the second aging process S9 while canceling these pre-sealing processes S4 and S10 and allowing the inside and outside of the housing 10 to communicate.

[0063] In another embodiment, a pre-seal release step S10 is performed before the compression deformation step S11 and a permanent sealing step S12 is performed after the compression deformation step S11. However, it is also possible to perform the pre-seal release step S10 after the compression deformation step S11 and then perform the permanent sealing step S12.

[0064] In addition, in one embodiment, after the compression deformation process S11, the permanent sealing process S12 and the extrusion release process S13 are performed sequentially. However, it is also possible to perform the extrusion release process S13 and the permanent sealing process S12 sequentially after the compression deformation process S11, in the opposite manner.

Claims

1. A method for manufacturing an energy storage device, the energy storage device comprising: An electrode body has a pair of electrode body planes, and electrode plates are stacked in a thickness direction orthogonal to the extension direction of the electrode body planes; Electrolyte; as well as The outer casing has a pair of sidewall portions facing the planes of the pair of electrode bodies, and houses the electrode bodies and the electrolyte. in, The manufacturing method of the energy storage device includes a compression deformation process, in which... Before the permanent seal is completed after initial charging and aging, the pair of housing sidewalls in the housing of the energy storage device are pressed towards the electrode body side. The electrode body, located between the pair of housing sidewalls, is compressed in the thickness direction, and At least one of the pair of outer shell sidewalls is plastically deformed to recess towards the electrode body, such that even after the compression is released, the electrode body is still continuously compressed by the pair of outer shell sidewalls in the thickness direction. After the compression deformation process, the following are provided: The permanent sealing process involves permanently sealing the housing of the energy storage device, which is currently in communication with the outside, in an airtight manner; and The compression release process releases the compression of the energy storage device during the compression deformation process.

2. The method for manufacturing the energy storage device according to claim 1, wherein, The electrode body has the characteristic that its dimension in the thickness direction increases with the increase of SOC. The compression deformation process is performed by bringing the energy storage device to a state of SOC below 30%.

3. The method for manufacturing the energy storage device according to claim 1 or 2, wherein, The compression deformation process is performed while the shell is in communication with the outside.

4. The method for manufacturing the energy storage device according to claim 1 or 2, wherein, The electrode body has the following electrode plates: The positive electrode plate has a layer of positive electrode active material, including positive electrode active material particles. and Negative electrode plate The positive electrode active material particles are lithium transition metal composite oxide particles with a composition in which Ni accounts for more than 50 mol% of the total amount of transition metals other than Li.

5. The method for manufacturing the energy storage device according to claim 3, wherein, The electrode body has the following electrode plates: The positive electrode plate has a layer of positive electrode active material, including positive electrode active material particles. and Negative electrode plate The positive electrode active material particles are lithium transition metal composite oxide particles with a composition in which Ni accounts for more than 50 mol% of the total amount of transition metals other than Li.

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