Method for manufacturing a secondary battery

Abstract

This method for manufacturing a secondary battery includes: a first pressure-reducing step of reducing an ambient pressure of an electrode body containing a positive-electrode material, a negative-electrode material, and an electrolyte; a preliminary charging step of carrying out preliminary charging of the electrode body; a pressure-increasing step of increasing the ambient pressure of the electrode body after the first pressure-reducing step and at least during the preliminary charging step; and a second pressure-reducing step of reducing the ambient pressure of the electrode body after the pressure-increasing step and at least during the preliminary charging step.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a secondary battery.

Background Art

[0002] Patent Document 1 discloses an example of a method for manufacturing a non-aqueous electrolyte secondary battery. The manufacturing method includes a step of adjusting the negative electrode potential of a vented secondary battery body in a state where gas can mutually flow between the inside and outside of the battery to 0.65 to 1.45 V (vs. Li / Li + ), and storing the vented secondary battery body in an environment where the atmospheric pressure is 0.07 MPa or less and the temperature is 20°C to 45°C.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Means for Solving the Problems

[0004] A method for manufacturing a secondary battery according to one aspect of the present disclosure includes a first depressurization step of depressurizing the atmosphere of an electrode body including a positive electrode material, a negative electrode material, and an electrolyte, a preliminary charging step of preliminarily charging the electrode body, a pressurization step of pressurizing the atmosphere of the electrode body after the first depressurization step and at least during the preliminary charging step, and a second depressurization step of depressurizing the atmosphere of the electrode body after the pressurization step and at least during the preliminary charging step.

Brief Description of the Drawings

[0005]

Figure 1

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Figure 9

Mode for Carrying Out the Invention

[0006] In the present embodiment, mainly, specific processes for performing preliminary charging on a secondary battery during manufacturing will be described. The preliminary charging may be the first charging of the secondary battery during manufacturing. In the present embodiment, prior to the description of the specific processes, the configuration of the secondary battery and an example of the manufacturing process of the secondary battery will be described.

[0007] 〔Configuration of Secondary Battery〕 FIG. 1 is a perspective view showing the appearance of a secondary battery 1. The secondary battery 1 is a battery that can be charged or discharged by being electrically connected to an external terminal. For example, at least one secondary battery 1 may be mounted in a power storage device for residential use, base station use, in-vehicle use, robots such as drones, and medical instruments. The secondary battery 1 may include a unit cell 10, connection terminals 21 and 22, and a second container 50. The configuration of the unit cell 10 will be described later.

[0008] The second container 50 may accommodate the unit cell 10. The second container 50 may be formed of, for example, an aluminum pouch film or a laminate film having a metal foil layer such as stainless steel or nickel. The aluminum pouch film may be one obtained by vapor-depositing aluminum on a film or one obtained by laminating an aluminum foil and a film. The material of the film may be, for example, polypropylene, polyethylene, nylon, or polyethylene terephthalate. The thickness of the second container 50 may be 50 μm or more and 300 μm or less, and may be, for example, 200 μm.

[0009] When the second container 50 is an aluminum pouch film, the second container 50 may have a configuration in which two aluminum pouch films are located on both sides in the stacking direction (Z-axis direction) of the unit cell 10. Further, when the second container 50 is an aluminum pouch film, the second container 50 may have a configuration in which one aluminum pouch film is folded in half and the unit cell 10 is located inside.

[0010] The connection terminals 21 and 22 may be terminals connected to an external terminal in order to take out power from the secondary battery 1 or supply power to the secondary battery 1. The connection terminals 21 and 22 may protrude from the inside to the outside of the second container 50. The material of the connection terminals 21 and 22 may be, for example, copper, aluminum, or nickel. The thickness of the connection terminals 21 and 22 may be 50 μm or more and 500 μm or less, and may be, for example, 200 μm. Further, the connection terminals 21 and 22 may be subjected to a surface treatment for improving the adhesiveness with an adhesive member (not shown). The adhesive member adheres the connection terminals 21 and 22 and the second container 50 located above and below the connection terminals 21 and 22 in order to determine the positions of the connection terminals 21 and 22 with respect to the second container 50.

[0011] FIG. 2 is a perspective view showing the appearance of the unit cell 10. As shown in FIG. 2, the unit cell 10 may include an electrode body 14 and a first container 15. The electrode body 14 may have a sheet-like shape. The sheet-like electrode body 14 may include a positive electrode 11 and a negative electrode 12.

[0012] The first container 15 may accommodate the electrode body 14. When a plurality of the first containers 15 accommodating the electrode body 14 are stacked, the plurality of first containers 15 may be adhered to each other by an adhesive layer (not shown). The material of the first container 15 may be, for example, film-like PET (polyethylene terephthalate) or nylon. More specifically, for example, two first containers 15 may be configured to be located on both sides in the stacking direction (Z-axis direction) of the unit cell 10. The thickness of the base material of the first container 15 may be, for example, 10 μm or more and 40 μm or less, and may be, for example, 25 μm. The material of the adhesive layer may be, for example, polypropylene or polyethylene.

[0013] The first container 15 may be, for example, transparent. FIG. 2 is a view showing a state in which the electrode body 14 can be confirmed through the first container 15 by using the transparent first container 15 for the unit cell 10.

[0014] The first container 15 may have a notch 16. For example, notches 16 may be provided in each of the first containers 15 on the positive electrode 11 side and the first containers 15 on the negative electrode 12 side. By providing the notch 16 as a portion not sealed in a part of the unit cell 10, gases generated by a decomposition reaction of the electrolytic solution or trace amounts of moisture can be released to the outside of the unit cell 10 inside the unit cell 10. Further, by providing the notch 16, a part on the positive electrode 11 side and a part on the negative electrode 12 side may have a configuration in which they are exposed from the first container 15. Alternatively, a part on the positive electrode 11 side and a part on the negative electrode 12 side may have a configuration in which they are not exposed from the first container 15. In the latter case, the internal space on the positive electrode 11 side of the unit cell 10 and the external space of the unit cell 10 may have a communicating configuration, and the internal space on the negative electrode 12 side of the unit cell 10 and the external space of the unit cell 10 may have a communicating configuration. Further, at the position of the notch 16 on the positive electrode 11 side, the first container 15 on the negative electrode 12 side may be exposed, and at the position of the notch 16 on the negative electrode 12 side, the first container 15 on the positive electrode 11 side may be exposed.

[0015] The positive electrode 11 may have an exposed portion 11e exposed from the first container 15. The negative electrode 12 may have an exposed portion 12e exposed from the first container 15. The connection terminals 21 and 22 may be electrically connected to the exposed portions 11e and 12e, respectively, by, for example, ultrasonic welding, laser welding, or resistance welding. Details of the positive electrode 11 and the negative electrode 12 will be described later.

[0016] The secondary battery 1 may have a configuration in which the unit cell 10 that houses the positive electrode 11 and the negative electrode 12 in the first container 15 is further housed in the second container 50. By having this configuration, since the electrode body 14 is doubly housed, the safety of the secondary battery 1 can be enhanced. Further, the second container 50 may be housed in a further container. However, the secondary battery 1 only needs to include the positive electrode 11 and the negative electrode 12, and only needs to be housed by at least one container.

[0017] In Embodiment 1, the secondary battery 1 has a configuration in which a plurality of unit cells 10 are stacked, for example, a configuration in which 10 layers of unit cells 10 are stacked. However, the secondary battery 1 according to the present disclosure may include a plurality of layers different from 10 layers of unit cells 10, or may include only one layer. When the secondary battery 1 includes a plurality of layers of unit cells 10, those unit cells 10 may be stacked. When the secondary battery 1 shown in FIG. 1 is viewed in plan, the portion excluding the connection terminals 21 and 22 may be substantially rectangular, or may have a different shape. Also, when the unit cell 10 shown in FIG. 2 is viewed in plan, the portion excluding the exposed portions 11e and 12e may be substantially rectangular, or may have a different shape.

[0018] FIG. 3 is an exploded model view showing a cross section taken along line III-III in FIG. 1. FIG. 4 is an exploded model view showing a cross section taken along line IV-IV in FIG. 1. For simplicity, the second housing 50 is omitted in FIGS. 3 and 4. Also, FIGS. 3 and 4 mainly show the positional relationship of each component. For this reason, the magnitude relationship of the thicknesses of each component is not necessarily as shown in FIGS. 3 and 4.

[0019] As shown in FIGS. 3 and 4, the secondary battery 1 may further include a first protective member 30. The first protective member 30 may protect a first connection portion that electrically connects the exposed portions 11e exposed from the first housing 15 of each unit cell 10 to each other, and a second connection portion that electrically connects the exposed portions 12e exposed from the first housing 15 of each unit cell 10 to each other. The exposed portions 11e and the exposed portions 12e may be connected to each other by, for example, ultrasonic welding, laser welding, or resistance welding. In FIGS. 3 and 4, the exposed portions 11e of the positive electrodes 11 and the exposed portions 12e of the negative electrodes 12 are not connected to each other, but are actually connected as described above.

[0020] The material of the first protective member 30 may be, for example, a film-shaped polyolefin or polyimide. The first protective member 30 may be adhered to the exposed portions 11e and 12e by an adhesive layer (not shown). Also, the material of the adhesive layer in the first protective member 30 may be any material that is difficult to elute into the electrolytic solution (electrolyte). The material of the adhesive layer may be, for example, an acrylic adhesive.

[0021] In the present embodiment, the first protective member 30 may cover a part of the first container 15 from the first connection portion and the second connection portion. Thereby, when stress is generated in the exposed portion 11e or 12e, stress concentration is less likely to occur, so that the possibility of damage or breakage of the exposed portion 11e or 12e in the vicinity of the first connection portion and the second connection portion can be reduced. However, the first protective member 30 only needs to protect at least the first connection portion and the second connection portion, and does not necessarily have to cover from the first connection portion and the second connection portion to the first container 15.

[0022] Also, as shown in FIGS. 3 and 4, the positive electrode 11 may have an electrode conductor 11a and a positive electrode active material layer 11b. The negative electrode 12 may have an electrode conductor 12a and a negative electrode active material layer 12b.

[0023] The electrode conductor 11a may be, for example, an aluminum foil. The thickness of the electrode conductor 11a may be 5 μm or more and 25 μm or less, and may be, for example, 10 μm. The electrode conductor 12a may be, for example, a copper foil. The thickness of the electrode conductor 12a may be 5 μm or more and 25 μm or less, and may be, for example, 10 μm.

[0024] FIG. 5 is a cross-sectional view showing a specific structure of the electrode body 14. As shown in FIG. 5, the positive electrode active material layer 11b may be a layer of a positive electrode material that is a mixture of a positive electrode active material 11c and a conductive assistant 11d. Further, the negative electrode active material layer 12b may be a layer of a negative electrode material that is a mixture of a negative electrode active material 12c and a conductive assistant 12d. The positive electrode active material 11c may be, for example, lithium cobaltate, lithium nickelate, lithium iron phosphate, or lithium manganate. The negative electrode active material 12c may be, for example, graphite or lithium titanate. The conductive assistants 11d and 12d may be, for example, carbon black or acetylene black. However, the positive electrode active material 11c, the negative electrode active material 12c, the conductive assistants 11d and 12d are not limited thereto.

[0025] The positive electrode material may have a so-called clay-like property in which an electrolytic solution is mixed into a mixture composed of the positive electrode active material 11c and the conductive assistant 11d. The negative electrode material may have a so-called clay-like property in which an electrolytic solution is mixed into a mixture composed of the negative electrode active material 12c and the conductive assistant 12d. The positive electrode 11 may be an electrode in which the positive electrode material is coated on the electrode conductor 11a. The negative electrode 12 may be an electrode in which the negative electrode material is coated on the electrode conductor 12a.

[0026] The electrolytic solution is obtained by dissolving a lithium salt, which is an electrolyte, in a non-aqueous solvent. As the non-aqueous solvent, a carbonate-based solvent may be used. As the carbonate-based solvent, γ-butyrolactone may be used, ethylene carbonate may be used, or both γ-butyrolactone and ethylene carbonate may be used. Further, as long as the carbonate-based solvent contains at least one of γ-butyrolactone and ethylene carbonate, it may contain other solvents. Examples of other solvents include propylene carbonate, dimethyl carbonate, dimethoxyethane, diethyl carbonate, tetrahydrofuran, and triethylene glycol dimethyl ether. As the electrolyte, lithium hexafluorophosphate or lithium bis(fluorosulfonyl)imide (LiFSI) may be used.

[0027] Further, the electrode body 14 may further include a separator 13. The positive electrode 11, the negative electrode 12, and the separator 13 may have a positional relationship such that the positive electrode active material layer 11b and the negative electrode active material layer 12b are in contact with the separator 13. That is, the unit cell 10 may have a structure in which the positive electrode 11 and the negative electrode 12 are stacked via the separator 13. The separator 13 may function as an insulating member that insulates the positive electrode 11 and the negative electrode 12. For the separator 13, for example, a sheet-like nonwoven fabric or a porous material may be used.

[0028] When using a porous material as the separator 13, specifically, a porous film made of a thermoplastic resin having a melting point of about 80°C to 140°C may be used. As the thermoplastic resin, for example, polyolefin-based polymers such as polypropylene and polyethylene, or polyethylene terephthalate may be used.

[0029] When using a positive electrode material and a negative electrode material having a clay-like property, a binder may not be used between the positive electrode, the negative electrode, and the separator. Also, before forming the electrodes of the positive electrode and the negative electrode, an electrolytic solution is mixed into the positive electrode material and the negative electrode material. Therefore, the performance of the positive electrode and the negative electrode can be improved. By mixing the electrolytic solution into the positive electrode material and the negative electrode material, the number of steps in the electrode forming of the positive electrode and the negative electrode can be reduced compared to the case of using a positive electrode material and a negative electrode material without the electrolytic solution mixed in. Also, in the manufacturing process of the secondary battery, the step of injecting the electrolytic solution can be reduced. Further, compared to the case of using a positive electrode material and a negative electrode material without the electrolytic solution mixed in, the positive electrode material and the negative electrode material can be thickly coated on the electrode conductor. Therefore, in realizing a secondary battery having a predetermined power storage amount, the number of electrode conductors and separators to be used can be reduced compared to the case of using a positive electrode material and a negative electrode material not having a clay-like property. Therefore, the member cost can be reduced and the energy density can be increased.

[0030] The positive electrode material and the negative electrode material do not necessarily have a clay-like property. In this case, the electrolyte may not be mixed into the positive electrode active material 11c and the negative electrode active material 12c. For example, the positive electrode material is a positive electrode slurry composed of a mixture of the positive electrode active material 11c and the conductive assistant 11d, a binder, and a solvent. The positive electrode slurry may be applied to the electrode conductor 11a and dried to form the positive electrode active material layer 11b. Further, the negative electrode material is a negative electrode slurry composed of a mixture of the negative electrode active material 12c and the conductive assistant 12d, a binder, and a solvent. The negative electrode slurry may be applied to the electrode conductor 12a and dried to form the negative electrode active material layer 12b. The binder may be polyvinylidene fluoride (PVdF) or polyethylene oxide (PEO), etc. The solvent may be an organic solvent such as N-methyl-2-pyrrolidone (NMP). Also in this case, the inside of the unit cell 10 is filled with the electrolyte, and the electrolyte may be impregnated and held in the separator 13.

[0031] The secondary battery according to the present disclosure may include an electrode body containing at least a positive electrode material, a negative electrode material, and an electrolyte. The secondary battery according to the present disclosure may be any secondary battery as long as it is pre-charged and gas is generated from the electrode body of the secondary battery during the manufacturing stage.

[0032] 〔Manufacturing Process of Secondary Battery〕 FIG. 6 is a flowchart showing an example of the manufacturing process (manufacturing method) of the secondary battery 1. The second container 50 is assumed to be composed of two aluminum pouch films.

[0033] In the manufacturing process of the secondary battery 1, a manufacturing apparatus (not shown) for manufacturing the secondary battery 1 first manufactures the positive electrode 11 and the negative electrode 12 (S1 and S2).

[0034] The positive electrode 11 is manufactured as follows, for example. The manufacturing apparatus pulverizes the positive electrode active material 11c and the conductive assistant 11d as raw materials, and then mixes the positive electrode active material 11c and the conductive assistant 11d. The manufacturing apparatus manufactures (slurries) a clay-like positive electrode material by kneading while introducing an electrolytic solution into the mixture of the positive electrode active material 11c and the conductive assistant 11d. Thereafter, the manufacturing apparatus applies the clay-like positive electrode material to the electrode conductor 11a formed by, for example, punching a metal foil (for example, an aluminum foil). That is, the electrode conductor 11a and the positive electrode active material layer 11b are laminated, and the integrated positive electrode 11 is manufactured. The first container 15 may be laminated on one surface of the electrode conductor 11a in advance, and then the positive electrode material may be applied to the other surface. That is, the positive electrode 11 laminated by the first container 15 may be manufactured.

[0035] The negative electrode 12 is manufactured as follows, for example. The manufacturing apparatus pulverizes the negative electrode active material 12c and the conductive assistant 12d as raw materials, and then mixes the negative electrode active material 12c and the conductive assistant 12d. The manufacturing apparatus manufactures (slurries) a clay-like negative electrode material by kneading while introducing an electrolytic solution into the mixture of the negative electrode active material 12c and the conductive assistant 12d. Thereafter, the manufacturing apparatus applies the clay-like negative electrode material to the electrode conductor 12a formed by, for example, punching a metal foil (for example, a copper foil). That is, the electrode conductor 12a and the negative electrode active material layer 12b are laminated, and the integrated negative electrode 12 is manufactured. The first container 15 may be laminated on one surface of the electrode conductor 12a in advance, and then the negative electrode material may be applied to the other surface. That is, the negative electrode 12 laminated by the first container 15 may be manufactured.

[0036] Next, the manufacturing apparatus forms the electrode body 14 by bonding the positive electrode 11 and the negative electrode 12 with the separator 13 sandwiched therebetween. Then, the first containers 15 are respectively superposed on the positive electrode 11 side and the negative electrode 12 side of the electrode body 14, and the first containers 15 are bonded to each other at a portion outside the outer periphery of the electrode body 14 in the first containers 15, thereby sealing the electrode body 14 between the first containers 15. At the portion of the notch 16 in the first container 15, the first containers 15 are not bonded to each other, and a configuration is formed in which the space inside the unit cell 10 communicates with the space outside the unit cell 10. In other words, except for a part of the outer periphery of the first container 15 on the positive electrode 11 side and the first container 15 on the negative electrode 12 side, the electrode body 14 is sealed at the outer periphery. The unsealed portion becomes the notch 16. In this way, the unit cell 10 is manufactured (S3).

[0037] Through the steps of S1 to S3, a plurality of unit cells 10 are manufactured. The manufacturing apparatus stacks the manufactured plurality of unit cells 10 (S4). Next, the manufacturing apparatus welds the connection terminals 21 and 22 to the electrode conductors 11a and 12a of the stacked unit cells 10 (S5). Specifically, the manufacturing apparatus welds the exposed portions 11e of the plurality of electrode conductors 11a to each other, and welds the connection terminal 21 to the outermost exposed portion 11ea. Further, the manufacturing apparatus welds the exposed portions 12e of the plurality of electrode conductors 12a to each other, and welds the connection terminal 22 to the outermost exposed portion 12ea.

[0038] Furthermore, the manufacturing apparatus welds the unit cells 10 to each other at the outer periphery excluding the notch 16 (S6). The unit cells 10 may be welded to each other at the outer periphery of the unit cell 10 by, for example, ultrasonic welding, thermal welding, or an adhesive tape.

[0039] Subsequently, the manufacturing apparatus temporarily thermally welds an aluminum pouch film, which is the material of the second container 50, to the outermost surfaces of one unit cell 10 and the other unit cell 10, which are located on the outermost side among the plurality of unit cells 10 with welded outer peripheries (S7). The temporary thermal welding is for determining the position of the aluminum pouch film with respect to the unit cell 10. The temporary thermal welding may be a low-strength welding that can be peeled off from the unit cell 10 as necessary. After determining the position of the aluminum pouch film, the manufacturing apparatus bonds the aluminum pouch films to each other at a site outside the outer periphery of the unit cell 10 and welds three sides out of the four sides of the substantially rectangular aluminum pouch film (S8). In the case of a configuration where one aluminum pouch film is folded in half and the unit cell 10 is located inside, two sides out of the remaining three sides may be welded. Next, the manufacturing apparatus cuts the outer shape of the aluminum pouch film into a desired shape in a state where three sides of the aluminum pouch film are welded (S9). The aluminum pouch film may be cut into a desired shape, for example, before performing the temporary thermal welding in S7.

[0040] Next, the manufacturing apparatus pre-charges the electrode body 14 of the secondary battery in a state where three sides of the aluminum pouch film are welded (S10). The pre-charging may be performed by a pre-charging device 4 included in the manufacturing apparatus. Details of the configuration and processing of the pre-charging device 4 will be described later. The pre-charging is performed to form a high-quality SEI (Solid Electrolyte Interphase) on the surface of the negative electrode 12. Also, particularly during pre-charging, gas is generated from the electrode body 14. The gas is, for example, a by-product generated during SEI formation by the reaction of the electrolytic solution and the negative electrode material, etc. Also, the gas is generated, for example, by the electrolysis of trace amounts of water contained in the electrolytic solution, etc. The gas can be discharged from the notch 16 and the non-welded portion of the aluminum pouch film.

[0041] In addition, three sides of the aluminum pouch film containing a plurality of unit cells 10 are closed, and one side is open. That is, the aluminum pouch film is only provided with an opening through which gas can be discharged. Therefore, even if the electrolytic solution leaks from the unit cell 10 during the preliminary charging, the electrolytic solution can be retained inside the aluminum pouch film. Accordingly, the possibility of production troubles can be reduced.

[0042] Next, while evacuating the air in the second container 50, the manufacturing apparatus welds one side of the aluminum pouch film that has not been welded up to the step of preliminary charging of S10 to manufacture the secondary battery 1. In other words, the inside of the aluminum pouch film is vacuum-sealed (S11). In the vacuum sealing, by welding the last side of the aluminum pouch film, the second container 50 can be formed and the secondary battery 1 can be manufactured.

[0043] The above-described steps may be interchanged as necessary. For example, the manufacturing of the positive electrode 11 and the manufacturing of the negative electrode 12 may be executed in parallel, or the negative electrode 12 may be manufactured after the manufacturing of the positive electrode 11, or the positive electrode 11 may be manufactured after the manufacturing of the negative electrode 12. Also, for example, the step of S5 may be executed before the step of S4, and the steps of S10 and S11 may be executed before the step of S9.

[0044] 〔Details of Preliminary Charging〕 Hereinafter, the details of the preliminary charging in S10 of FIG. 6 will be described. As described above, the preliminary charging is executed by the preliminary charging device 4. Hereinafter, after describing a configuration example of the preliminary charging device 4, a processing example of the preliminary charging device 4 will be described.

[0045] <Configuration of Preliminary Charging Device> The preliminary charging device 4 may be a device that performs preliminary charging on a secondary battery during manufacturing. The secondary battery during manufacturing that is the object of preliminary charging may have a structure that allows charging of the electrode body 14 by the preliminary charging device 4 and that allows the gas generated inside the electrode body 14 to be discharged to the outside of the electrode body 14. In the present embodiment, the secondary battery during manufacturing that is the object of preliminary charging is a secondary battery in which three sides of an aluminum pouch film are welded to close it and one side is not welded. In the following description, the secondary battery during manufacturing is referred to as the secondary battery 1a.

[0046] FIG. 7 is a schematic diagram showing an example of a schematic configuration of the preliminary charging device 4. FIG. 7 is a schematic diagram of the preliminary charging device 4 when viewed by an operator from the side (front side) where the secondary battery 1a is accommodated. FIG. 8 is a model diagram showing a disassembled state in which a spacer 5 is arranged between two adjacent trays 44 in the vertical direction. FIG. 8 shows a state before the secondary battery 1a is accommodated in the tray 44.

[0047] As shown in FIG. 7, the preliminary charging device 4 may include a pressing unit 41 and a housing unit 42.

[0048] The pressing unit 41 may be a mechanism that places the electrode body 14 of the secondary battery 1a in a pressurized state by mechanical pressure. For example, an air cylinder or a hydraulic cylinder may be used for the pressing unit 41. The housing unit 42 may be a housing that houses the secondary battery 1a pressurized by the pressing unit 41.

[0049] The above-mentioned "pressurized state" refers to the state after the application of mechanical pressure to the electrode body 14 is started. That is, the "pressurized state" refers to the state from when mechanical pressure is applied to the electrode body 14 until a predetermined specified value is reached, and the state in which the specified value of mechanical pressure is applied to the electrode body 14. The specified value may be set in consideration of, for example, efficient gas venting from the electrode body 14. Also, the pressing direction may be a direction along the normal directions of the two main surfaces (the surfaces having the largest area) that form the front and back of the secondary battery 1a.

[0050] The accommodating portion 42 may include a pedestal 43, a tray 44, and a clamp 45. In region A1 of FIG. 7, a state in which the tray 44 is removed from the pedestal 43 is shown.

[0051] The tray 44 may be placed on the pedestal 43. The pedestal 43 may be provided in the accommodating portion 42 so as to be movable in the vertical direction (z-axis direction). The tray 44 may be configured to accommodate at least two of the plurality of secondary batteries 1a (electrode bodies 14) accommodated in the accommodating portion 42. The tray 44 may have, for example, a shallow substantially box-shaped configuration with one side open, and may be capable of accommodating a plurality of secondary batteries 1a stacked thereon. In other words, the tray 44 may be capable of accommodating a plurality of sheet-like electrode bodies 14 constituting the secondary battery 1a in a state where they are stacked in the stacking direction of the positive electrode 11 and the negative electrode 12 constituting the electrode body 14. In the example of FIG. 7, in the accommodating portion 42, four-stage pedestals 43 arranged in the vertical direction are provided in two rows. The arrangement and number of the pedestals 43 are not limited to this. As long as a plurality of trays 44 are stacked and arranged along the pressing direction by the pressing portion 41 so that the pressing portion 41 can apply mechanical pressure to the secondary batteries 1a accommodated in the tray 44 on the pedestal 43. In other words, the plurality of trays 44 may be arranged so as to overlap in the pressing direction in a state where they each accommodate a plurality of secondary batteries 1a. Then, the mechanical pressure applied to the secondary batteries 1a in the upper tray 44 by the pressing portion 41 is applied to the secondary batteries 1a accommodated in the lower tray 44 via the upper tray 44. The pressing direction may be a direction along the normal direction of the main surface of the secondary battery 1a (electrode body 14).

[0052] In this embodiment, the pressing part 41 may apply mechanical pressure from above (ceiling part 42a side) of the trays 44 arranged in a stacked manner by descending from the ceiling part 42a to the bottom part 42b of the accommodating part 42. Specifically, when the pressing part 41 descends, it pushes the uppermost tray 44 downward. Along with this pushing, the uppermost pedestal 43 descends. When the pressing part 41 further descends, the uppermost pedestal 43 pushes the pedestal 43 below it downward. That is, by the descent of the pressing part 41, the upper pedestal 43 pushes the lower pedestal 43, and mechanical pressure is applied to the plurality of secondary batteries 1a arranged between the uppermost pedestal 43 and the lowermost pedestal 43. Thereby, the pressing part 41 may put each of the plurality of secondary batteries 1a accommodated in the tray 44 in a pressed state.

[0053] By stacking and accommodating the plurality of secondary batteries 1a separately in a plurality of trays 44, the posture of the secondary batteries 1a during pressing can be stabilized more than when all the secondary batteries 1a are stacked together. Also, by stacking and arranging a plurality of trays 44 and applying mechanical pressure from above the stacked plurality of trays 44, all the secondary batteries 1a can be pressed together by one pressing part 41.

[0054] In this embodiment, the pressing part 41 is provided on the ceiling part 42a side and applies mechanical pressure to the electrode body 14 of the secondary battery 1a by moving from the ceiling part 42a to the bottom part 42b, but it is not limited to this. For example, the pressing part 41 may be provided on the bottom part 42b side and apply mechanical pressure to the electrode body 14 of the secondary battery 1a by moving from the bottom part 42b to the ceiling part 42a. Also, the pressing part 41 may be provided on each of the ceiling part 42a and the bottom part 42b. That is, mechanical pressure may be applied to the electrode body 14 of the secondary batteries 1a accommodated in the plurality of trays 44 arranged in a stacked manner from at least one of above and below the plurality of trays 44.

[0055] As described above, the preliminary charging device 4 shown in FIG. 7 has a structure in which mechanical pressure is applied from above the preliminary charging device 4 in a state where the secondary battery 1a is disposed in the housing portion 42 such that the main surface of the secondary battery 1a is substantially parallel to the horizontal plane. However, the preliminary charging device 4 may apply mechanical pressure from the side of the preliminary charging device 4 in a state where the secondary battery 1a is disposed in the housing portion 42 such that the main surface of the secondary battery 1a is substantially perpendicular to the horizontal plane. In this case, the plurality of trays 44 may be arranged such that the open side faces the side direction of the preliminary charging device 4. That is, the plurality of trays 44 may be arranged along the pressing direction.

[0056] In other words, in the housing portion 42, the plurality of secondary batteries 1a (electrode bodies 14) may be arranged side by side such that at least one of the two main surfaces of the secondary battery 1a faces the main surface of another secondary battery 1a. In that state, the preliminary charging device 4 may apply mechanical pressure from at least one side of the two outermost electrode bodies. In this case, the preliminary charging device 4 can press the plurality of secondary batteries 1a together.

[0057] The clamp 45 may be a connection part for the preliminary charging device 4 to supply (energize) current to the electrode body 14 of the secondary battery 1a. As shown in FIG. 7, the clamp 45 is provided on the back side of the preliminary charging device 4. The clamp 45 is provided to face the tray 44 disposed on each pedestal 43. The clamp 45 electrically connects the preliminary charging device 4 to the connection terminals 21 and 22 by sandwiching the connection terminals 21 and 22 of the plurality of secondary batteries 1a respectively housed on top of each other on each tray 44. However, the mechanism for supplying current to the connection terminals 21 and 22 is not limited to a mechanism that sandwiches each of the connection terminals 21 and 22 like the clamp 45, and any configuration that can electrically connect the preliminary charging device 4 to the connection terminals 21 and 22 may be used. The preliminary charging device 4 executes preliminary charging of the electrode body 14 by supplying current to the electrode body 14 when, for example, about 2 to 10 secondary batteries 1a housed in one tray 44 are electrically connected. The preliminary charging device 4 may supply a current of, for example, 5 A or more and 80 A or less to the connection terminals 21 and 22. The magnitude of the current may be appropriately adjusted so that a predetermined current flows through one electrode body 14.

[0058] As described above, each of the plurality of unit cells 10 is connected to the connection terminals 21 and 22. Therefore, by simply electrically connecting the connection terminals 21 and 22 to the preliminary charging device 4, the electrode bodies 14 of the plurality of unit cells 10 can be charged simultaneously. Accordingly, since the manufacturing efficiency of the secondary battery 1 can be improved, the productivity of the secondary battery 1 can be improved.

[0059] In the example of FIG. 8, four secondary batteries 1a are stacked and housed in the tray 44, but the number is not limited to four, and a plurality of secondary batteries 1a may be stacked and housed. Also, the number of secondary batteries 1a housed in the tray 44 may be determined in advance, and for example, 2 to 10 secondary batteries 1a may be stacked and housed.

[0060] Further, as shown in FIG. 8, a spacer 5 may be disposed between two adjacent trays 44. The pressing portion 41 may press each of the plurality of secondary batteries 1a in a state where the spacer 5 is disposed. The sizes of the upper surface 5a and the lower surface 5b of the spacer 5 may be sizes that can be accommodated in the tray 44. Further, the height (thickness) HS of the spacer 5 may be a thickness such that when a prescribed number of secondary batteries 1a are accommodated in the tray 44 and pressed by the pressing portion 41, two adjacent trays 44 do not come into contact with each other. By disposing such a spacer 5, it is possible to reduce the possibility that the trays 44 come into contact with each other during pressing by the pressing portion 41 and the electrode body 14 is not properly pressed.

[0061] The mechanical pressure applied by the pressing portion 41 to the secondary battery 1a may be a pressure equivalent to the mechanical pressure applied to the plurality of secondary batteries 1 in a power storage device (not shown) formed by stacking the plurality of secondary batteries 1. That is, the mechanical pressure applied to the electrode body 14 during preliminary charging and the mechanical pressure applied to the electrode body 14 in the power storage device as a finished product may be equivalent pressures. In the power storage device, elastic members may be provided on both side surfaces of the housing constituting the power storage device, and mechanical pressure may be applied to the plurality of stacked secondary batteries 1 from both sides of the plurality of secondary batteries 1. The mechanical pressure may be, for example, 0.1 kgf / cm 2 or more and 1.4 kgf / cm 2 or less.

[0062] In the present embodiment, a plurality of trays 44 are provided in the accommodating portion 42, but at least one tray 44 may be provided. Further, in the present embodiment, a plurality of secondary batteries 1a are accommodated in one tray 44, but at least one secondary battery 1a may be accommodated. That is, the preliminary charging device 4 only needs to be able to apply mechanical pressure to at least one electrode body 14.

[0063] In addition, the tray 44 and the spacer 5 may be made of an insulating material, for example, a plastic such as polyethylene or polyvinyl chloride. Also, the tray 44 and the spacer 5 may be made of the same material or different materials. Further, the shape of the tray 44 is not limited to a shallow box shape as long as the tray 44 can place the secondary battery 1a. The shape of the tray 44 may be, for example, a tray-like shape such as a flat plate, or a tray-like plate with guide pins standing up to position the portion for accommodating the secondary battery 1a.

[0064] Also, in this specification, accommodating the secondary battery 1a (electrode body 14) in the tray 44 shall mean arranging at least one secondary battery 1a (electrode body 14) at a predetermined position of the tray 44. Further, although the example of accommodating the secondary battery 1a in the tray 44 has been described above, the unit cell 10 may be accommodated in the tray 44, and the preliminary charging device 4 may apply mechanical pressure to the unit cell 10.

[0065] <Processing of the Preliminary Charging Device> Next, the specific processing when the preliminary charging device 4 preliminarily charges the electrode body 14 will be described with reference to the flowchart of FIG. 9. FIG. 9 is a flowchart showing an example of the processing of the preliminary charging device 4.

[0066] First, the operator prepares at least one or more trays 44 and houses a plurality of secondary batteries 1a in the trays 44 (S21). Then, the trays 44 are placed in the housing portion 42 of the preliminary charging device 4. At this time, the operator may stack and arrange a plurality of trays 44, and may also place a spacer 5 between two adjacent trays 44. Next, when the preliminary charging device 4 receives an input operation for starting preliminary charging by the operator, the clamping terminals 21 and 22 are clamped by the clamp 45, thereby electrically connecting the clamp 45 to the connection terminals 21 and 22 (S22). In the state of S22, the preliminary charging device 4 is not performing current supply to the connection terminals 21 and 22. In this state, the preliminary charging device 4 starts pressurizing the secondary battery 1a by controlling the pressurizing portion 41 (S23). That is, in S23, the preliminary charging device 4 starts applying mechanical pressure to the electrode body 14 of the secondary battery 1a. The process of S23 may be executed prior to the process of S22, or the processes of S22 and S23 may be executed in parallel.

[0067] Next, the preliminary charging device 4 may set the atmosphere covering the electrode body 14 of the secondary battery 1a to a reduced pressure state (first pressure reduction step: S24). By this pressure reduction, even if gas is generated in the electrode body 14 before preliminary charging of the electrode body 14, the gas can be removed from the secondary battery 1a. Further, since the gas from the electrode body 14 can be removed by the first pressure reduction step, the adhesion of each member of the secondary battery 1a can be improved.

[0068] The above-mentioned "atmosphere covering the electrode body 14 (atmosphere of the electrode body 14)" refers to the gas filling the environment in which the secondary battery 1a is placed, and may be, for example, air. However, the periphery of the secondary battery 1a may be filled with a gas other than air (for example, nitrogen). In the present embodiment, the atmosphere of the electrode body 14 refers to the air filling the inside of the housing portion 42.

[0069] Further, the "depressurized state" means a state in which the pressure around the electrode body 14 (the atmospheric pressure in the housing portion 42 in this embodiment) becomes lower than the pressure immediately before the change. That is, the "depressurized state" includes a state until the pressure around the electrode body 14 reaches a first specified value determined in advance from the pressure immediately before the change, and a state in which the pressure is maintained at the first specified value. The first specified value may be set, for example, in consideration of pre-charging for the efficient electrode body 14 and gas venting from the efficient secondary battery 1a.

[0070] The pre-charging device 4 may start pre-charging the electrode body 14 after making the atmosphere around the electrode body 14 into a depressurized state (S25). That is, in S25, the pre-charging device 4 starts supplying current to the electrode body 14 via the clamp 45.

[0071] Next, the pre-charging device 4 may make the atmosphere around the electrode body 14 into a pressurized state (pressurizing step: S26). The "pressurized state" means a state in which the pressure around the electrode body 14 becomes higher than the pressure immediately before the change. That is, the "pressurized state" includes a state until the pressure around the electrode body 14 reaches a second specified value determined in advance from the pressure immediately before the change, and a state in which the pressure is maintained at the second specified value. The second specified value may also be set, for example, in consideration of pre-charging for the efficient electrode body 14 and gas venting from the efficient secondary battery 1a.

[0072] For example, in the first depressurizing step of S24, the pre-charging device 4 may make the atmosphere around the electrode body 14 from the atmospheric pressure state to the vacuum state. Also, in the pressurizing step of S26, the pre-charging device 4 may make the atmosphere around the electrode body 14 from the vacuum state to the atmospheric pressure state. In this case, the first specified value may be about 10 -1 ~10 -3 atmospheres, and the second specified value may be about 1 atmosphere.

[0073] For example, a first valve may be provided in the middle of a connecting pipe (not shown) that connects the accommodating portion 42 and a vacuum pump (not shown). Also, a second valve may be provided in the middle of a connecting pipe (not shown) that connects the inside and the outside of the accommodating portion 42, or a connecting pipe (not shown) that connects the accommodating portion 42 and a gas supply portion (not shown) such as nitrogen. In this case, the preliminary charging device 4 may depressurize the inside of the accommodating portion 42 (i.e., the atmosphere of the electrode body 14) by keeping the first valve open and the second valve closed. Also, the preliminary charging device 4 may increase the pressure inside the accommodating portion 42 by keeping the second valve open and the first valve closed.

[0074] The preliminary charging device 4 starts the pressure increasing step of S26 after starting the preliminary charging for the electrode body 14 in S25, but is not limited to this. The preliminary charging device 4 may start the preliminary charging for the electrode body 14 in S25 after starting the pressure increasing step of S26, or the start of the preliminary charging for the electrode body 14 in S25 and the start of the pressure increasing step of S26 may be executed simultaneously. The pressure increasing step of S26 may be executed after the first depressurizing step of S24.

[0075] Specifically, the preliminary charging device 4 may start the preliminary charging for the electrode body 14 before keeping the second valve open and the first valve closed. In this case, the preliminary charging will be started during the first depressurizing step. Also, the preliminary charging device 4 may start the preliminary charging for the electrode body 14 simultaneously with keeping the second valve open and the first valve closed. Also, the preliminary charging device 4 may start the preliminary charging for the electrode body 14 after keeping the second valve open and the first valve closed and before the pressure around the electrode body 14 reaches the second specified value. Also, the preliminary charging device 4 may start the preliminary charging after keeping the second valve open and the first valve closed and after the pressure around the electrode body 14 has reached the second specified value.

[0076] Next, the preliminary charging device 4 may depressurize the atmosphere of the electrode body 14 (second depressurization step: S27). For example, also in the second depressurization step, the preliminary charging device 4 may change the atmosphere of the electrode body 14 from the atmospheric pressure state to the vacuum state. Next, the preliminary charging device 4 determines whether the boosting step in S26 and the second depressurization step in S27 have been executed the first specified number of times (S28). In the present embodiment, the first specified number of times may be set to a plurality of times. The first specified number of times may be set such that, for example, the number of executions of the boosting step and the second depressurization step is each any one of 2 to 10 times. When the preliminary charging device 4 determines that the boosting step in S26 and the second depressurization step in S27 have been executed the first specified number of times (YES in S28), the preliminary charging of the electrode body 14 is terminated. On the other hand, when the preliminary charging device 4 determines that the boosting step in S26 and the second depressurization step in S27 have not been executed the first specified number of times (NO in S28), the process in S26 is executed again.

[0077] As described above, the preliminary charging device 4 starts the preliminary charging of the electrode body 14 at S25 and ends the preliminary charging of the electrode body 14 at S29. That is, in the present embodiment, the preliminary charging device 4 may execute a preliminary charging step of preliminarily charging the electrode body 14 in S25 to S29 during or after the first depressurization step in S24. Further, the preliminary charging device 4 may execute the boosting step in S26 after the first depressurization step in S24, and execute the second depressurization step in S27 after the boosting step. By this boosting step and the second depressurization step, in the boosted state, the electrode body 14 can be charged substantially uniformly (without unevenness) over the entire electrode body 14, and in the depressurized state, the amount of gas escaping from the electrode body 14 per unit time can be made larger than in the boosted state. Therefore, while efficiently extracting gas from the electrode body 14, the electrode body 14 can be efficiently charged.

[0078] It has been found by empirical rule that when the pressure is reduced, a phenomenon occurs in which the entire electrode body 14 cannot be uniformly charged. This phenomenon is presumably because when the pressure is reduced, the gas remaining in the electrode body 14 without escaping from the electrode body 14 expands, increasing the resistance of the electrode body 14. Therefore, the preliminary charging device 4 not only efficiently extracts gas from the electrode body 14 by performing the second pressure reduction step in the preliminary charging process, but also improves the charging efficiency of the electrode body 14 by performing the pressure increase step.

[0079] Further, the preliminary charging device 4 may start the pressure increase step almost simultaneously with the start of the preliminary charging in S25 and S26 after improving the adhesion of each member of the secondary battery 1a in the first pressure reduction step of S24. Therefore, the preliminary charging device 4 can charge the entire electrode body 14 more substantially uniformly.

[0080] Also, it has been found by empirical rule that the amount of gas escaping from the electrode body 14 per unit time is larger when the pressure of the atmosphere of the electrode body 14 is intermittently reduced rather than continuously reduced. According to this empirical rule, by performing the pressure increase step together with the second pressure reduction step as described above, gas can be efficiently extracted from the electrode body 14 during the preliminary charging. That is, while efficiently extracting gas from the electrode body 14, the electrode body 14 can be efficiently charged.

[0081] Also, during the period when the electrode body 14 is being preliminarily charged in the preliminary charging process, the period of the pressure increase state by the pressure increase step in S26 may be longer than the period of the pressure reduction state by the second pressure reduction step in S27. By making the period of the pressure increase state longer than the period of the pressure reduction state, it becomes possible to charge the entire electrode body 14 more uniformly.

[0082] The period of the boosting state in S26 may be set to a length of, for example, 5 minutes or more and 20 minutes or less. The period of the depressurizing state in S27 may be set to a length of, for example, 1 minute or more and 10 minutes or less. The lengths of the periods of the boosting state and the depressurizing state may be set in consideration of the current amount, the length of the pre-charging process period, the number of executions of the boosting process in S26 and the second depressurizing process in S27, etc., so that efficient pre-charging and gas venting are possible.

[0083] Also, in the present embodiment, as described above, the first specified number of times is set to a plurality of times. That is, the pre-charging device 4 may alternately and repeatedly execute the boosting process in S26 and the second depressurizing process in S27 a plurality of times during the pre-charging process. Thereby, since the second depressurizing process mainly for venting gas from the electrode body 14 can be intermittently executed, gas can be vented from the electrode body 14 evenly. However, the first specified number of times may be set to 1 time instead of a plurality of times. The first specified number of times may be set in consideration of the current amount, the first and second specified values, the value of the mechanical pressure, the lengths of the periods of the boosting process and the second depressurizing process, etc., so that efficient pre-charging and gas venting are possible.

[0084] Also, the pre-charging device 4 may end the pre-charging of the electrode body 14 during the second depressurizing process in S27. Gas is likely to be generated from the electrode body 14 due to the pre-charging of the electrode body 14. Therefore, the pre-charging device 4 can efficiently vent gas from the electrode body 14 by ending the pre-charging during the second depressurizing process. However, the pre-charging device 4 may end the pre-charging of the electrode body 14 simultaneously with the end of the second depressurizing process. Also, the pre-charging device 4 may end the pre-charging of the electrode body 14 during or simultaneously with the end of the boosting process in S30, which is executed after performing the boosting process and the second depressurizing process the first specified number of times.

[0085] The period of the preliminary charging process may be, for example, 50 minutes or more and 150 minutes or less. Also, the charging rate may be, for example, 0.05C or more and 0.3C or less. The charging rate (C rate) is an index representing the magnitude of the current when charging and discharging the secondary battery. 1C is defined as the current value when discharging from the fully charged state in 1 hour, or the current value when charging from the discharged state to the fully charged state. For example, 2C means the current value when discharging from the fully charged state in 1 / 2 hour, or the current value when charging from the discharged state to the fully charged state. Also, it is sufficient if the electrode body 14 can be charged with an amount of electricity equal to or more than the irreversible capacity portion, and the charging rate at the end of charging may be, for example, 10% or more and 30% or less.

[0086] In this embodiment, after the preliminary charging device 4 finishes the preliminary charging of the electrode body 14 in S29, the atmosphere of the electrode body 14 may be set to a pressurized state (pressure increasing step: S30). Next, the preliminary charging device 4 may set the atmosphere of the electrode body 14 to a depressurized state (second depressurization step: S31). Thus, after finishing the preliminary charging, the preliminary charging device 4 may execute the pressure increasing step and the second depressurization step. By the pressure increasing step and the second depressurization step, even after the preliminary charging is completed, gas can be removed from the electrode body 14. Also, according to the empirical rule described above, by executing the pressure increasing step together with the second depressurization step, gas can be efficiently removed from the electrode body 14 during the period after the preliminary charging is completed. Even when the preliminary charging device 4 finishes the preliminary charging of the electrode body 14 during the pressure increasing step of S30 or simultaneously with the end of the pressure increasing step, after finishing the preliminary charging, the pressure increasing step of S30 and the second depressurization step of S31 may be executed.

[0087] Also, after the preliminary charging is completed, the period of the depressurized state by the second depressurization step of S31 may be longer than the period of the pressurized state by the pressure increasing step of S30. During the preliminary charging, charging the electrode body 14 is emphasized. On the other hand, after the preliminary charging is completed, removing the gas generated in the electrode body 14 during charging of the electrode body 14 from the electrode body 14 is emphasized. Therefore, by making the period of the second depressurized state longer than the period of the pressurized state, gas can be efficiently removed from the electrode body 14 during the period after the preliminary charging is completed.

[0088] The period of the boosting state in S30 may be, for example, 1 minute or more and 10 minutes or less. The period of the depressurization state in S31 may be, for example, 5 minutes or more and 20 minutes or less. The lengths of the periods of the boosting state and the depressurization state may be set in consideration of the number of executions of the boosting step in S30 and the second depressurization step in S31 so that efficient gas venting is possible.

[0089] Incidentally, in the present embodiment, as described above, the preliminary charging device 4 executes the boosting step and the second depressurization step at least once each in each of the period of the preliminary charging steps of S25 to S29 and the period after the preliminary charging steps of S30 to S34. When one execution of the boosting step and the second depressurization step is referred to as one cycle, the time required for one cycle may be longer than the time during the period of the preliminary charging steps (the processing times of S26 and S27). The execution of the boosting step and the second depressurization step during the period of the preliminary charging steps is mainly aimed at efficiently performing both substantially uniform charging of the electrode body 14 and gas venting from the electrode body 14. On the other hand, the execution of the boosting step and the second depressurization step during the period after the preliminary charging steps is mainly aimed at gas venting from the electrode body 14. By setting the time required for one cycle as described above, it is easy to achieve the above main purpose.

[0090] Next, the preliminary charging device 4 determines whether it has executed the boosting process in S30 and the second pressure reduction process in S31 for the second specified number of times (S32). In the present embodiment, the second specified number of times may be set to a plurality of times. For example, the second specified number of times may be set such that the number of executions of the boosting process and the second pressure reduction process are each any one of 2 to 10 times. That is, the preliminary charging device 4 may alternately and repeatedly execute the boosting process in S30 and the second pressure reduction process in S31 even during the period after the completion of the preliminary charging. However, the second specified number of times may be set to 1 time instead of a plurality of times. The second specified number of times may also be set in consideration of the current amount, the first and second specified values, the value of the mechanical pressure, the length of the periods of the boosting process and the second pressure reduction process, etc., so that efficient preliminary charging and gas venting are possible.

[0091] When the preliminary charging device 4 determines that it has executed the boosting process in S30 and the second pressure reduction process in S31 for the second specified number of times (YES in S32), it may set the atmosphere of the electrode body 14 to a boosted state (S33). Next, the preliminary charging device 4 ends the pressurization of the secondary battery 1a (S34). The process of S34 may be executed prior to the process of S33, or the process of S33 and the process of S34 may be executed in parallel. On the other hand, when the preliminary charging device 4 determines that it has not executed the boosting process in S30 and the second pressure reduction process in S31 for the second specified number of times (NO in S32), it executes the process of S30 again.

[0092] As described above, the preliminary charging device 4 starts applying mechanical pressure to the electrode body 14 in S23 and ends applying mechanical pressurization to the electrode body 14 in S34. That is, in the present embodiment, the preliminary charging device 4 may continuously execute a pressurization process of setting the electrode body 14 to a pressurized state by mechanical pressure at least during the period of the preliminary charging process and the period after the preliminary charging process once. Also, in the present embodiment, the preliminary charging device 4 may execute the second pressure reduction process (pressure reduction process) in S27 at least once during the period of the preliminary filling process and execute the second pressure reduction process (pressure reduction process) in S31 at least once during the period after the preliminary filling process.

[0093] By performing the pressurization step and the second depressurization step during the preliminary charging, the gas generated during the preliminary charging can be removed from the electrode body 14. Also, by performing the pressurization step and the second depressurization step during the period after the preliminary charging is completed, the gas remaining or generated in the electrode body 14 can be removed from the electrode body 14 during the period after the preliminary charging is completed. Therefore, more gas generated from the electrode body 14 can be removed from the electrode body 14.

[0094] Also, when the preliminary charging device 4 continuously performs the pressurization step once, the pressurized state of the electrode body 14 by mechanical pressure is continued from during the preliminary charging to the period after the preliminary charging is completed. Therefore, gas can be efficiently removed from the electrode body 14. Further, when the preliminary charging device 4 performs the second depressurization step at least once during each of the period during the preliminary charging and the period after the preliminary charging is completed, the second depressurization step is intermittently performed. According to the above-mentioned rule of thumb, by intermittently performing the second depressurization step, gas can be efficiently removed from the electrode body 14.

[0095] However, the preliminary charging device 4 may perform the pressurization step a plurality of times during the period of the preliminary filling step and the period after the preliminary charging step. For example, when the preliminary charging is completed in S29, the preliminary charging device 4 may once terminate the application of mechanical pressure to the electrode body 14. Thereafter, when performing the pressure increasing step of, for example, S30, the preliminary charging device 4 may again perform the application of mechanical pressure to the electrode body 14.

[0096] Also, the preliminary charging device 4 may continuously perform the second depressurization step once during the period of the preliminary filling step and the period after the preliminary charging step. For example, the preliminary charging device 4 may continuously perform the second depressurization step of S27 until the pressure increasing step of S33 is performed. In this case, the preliminary charging device 4 does not have to perform S28, S30 to S32.

[0097] Also, in this embodiment, the preliminary charging device 4 executes the pressurization process during the preliminary charging process and after the preliminary charging process, but it is not necessary to execute the pressurization process. Even when the preliminary charging device 4 does not execute the pressurization process, the gas can be removed from the electrode body 14 by executing the boosting process and / or the second depressurization process during the preliminary charging process and / or after the preliminary charging process.

[0098] As described above, according to the manufacturing method of the secondary battery 1 according to the present disclosure, preliminary charging and gas extraction from the electrode body 14 can be efficiently performed. Therefore, the possibility of defective products of the secondary battery 1 can be reduced. Accordingly, the energy and resources consumed in manufacturing defective products of the secondary battery 1 can be saved, thus contributing to the achievement of sustainable development goals (SDGs).

[0099] 〔Supplementary Notes〕 As described above, the invention according to the present disclosure has been described based on the drawings and examples. However, the invention according to the present disclosure is not limited to the above-described embodiments. That is, the invention according to the present disclosure can be variously modified within the scope shown in the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that those skilled in the art can easily make various deformations or modifications based on the present disclosure. Also, note that these deformations or modifications are included in the scope of the present disclosure.

[0100] For example, the preliminary charging device 4 may start the preliminary charging of the electrode body 14 before the start (e.g., immediately before) or simultaneously with the first depressurization process. However, as described above, by performing the preliminary charging of the electrode body 14 during or after the first depressurization process, the gas can be removed from the electrode body 14, and the preliminary charging of the electrode body 14 can be performed in a state where the adhesion of each member of the secondary battery 1a is improved.

Explanation of Reference Numerals

[0101] 1 Secondary battery 5 Spacer 10 Unit cell 11 Positive electrode 12 Negative electrode 13 Separator 14 Electrode body 21, 22 Connection terminal

Claims

1. A first pressure reduction step of reducing the atmosphere of the electrode body including a positive electrode material, a negative electrode material, and an electrolyte to a reduced pressure state; A preliminary charging step of preliminarily charging the electrode body; A pressure increase step of increasing the atmosphere of the electrode body to a pressurized state after the first pressure reduction step and at least during the preliminary charging step; A second pressure reduction step of reducing the atmosphere of the electrode body to a reduced pressure state after the pressure increase step and at least during the preliminary charging step; A method for manufacturing a secondary battery, comprising:

2. The preliminary charging step is started during or after the first pressure reduction step. The method for manufacturing a secondary battery according to Claim 1.

3. During the period in which the electrode body is being preliminarily charged in the preliminary charging step, The period of the pressurized state by the pressure increase step is longer than the period of the reduced pressure state by the second pressure reduction step. The method for manufacturing a secondary battery according to Claim 1 or 2.

4. During the preliminary charging step, the pressure increase step and the second pressure reduction step are alternately executed a plurality of times. The method for manufacturing a secondary battery according to any one of Claims 1 to 3.

5. Even after the preliminary charging of the electrode body is completed in the preliminary charging step, the pressure increase step and the second pressure reduction step are executed. The method for manufacturing a secondary battery according to any one of Claims 1 to 4.

6. When the pressure increase step and the second pressure reduction step are executed after the preliminary charging of the electrode body is completed in the preliminary charging step, The period of the reduced pressure state by the second pressure reduction step is longer than the period of the pressurized state by the pressure increase step. The method for manufacturing a secondary battery according to Claim 5.

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