Method for manufacturing secondary battery

Abstract

To provide a method for manufacturing a secondary battery capable of reducing power consumption of a dehumidifier forming low dew point environment.SOLUTION: A secondary battery 10 includes: an electrode laminate 11 in which a positive electrode layer 20 and a negative electrode layer 30 are laminated; and an exterior body 14 that accommodates the electrode laminate 11. A method for manufacturing the secondary battery 10 includes: a positive electrode step S100 forming or storing the positive electrode layer 20; a negative electrode step S110 of forming or storing the negative electrode layer 30; and a battery assembly step S120 of laminating the positive electrode layer 20 and the negative electrode layer 30 and accommodating them in the exterior body 14. Based on a dew point required in each step, a dehumidified gas sent from a dehumidifier 70 is caused to flow in order from a step with a lower dew point.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for producing a secondary battery. [Background technology]

[0002] In recent years, research and development into secondary batteries that contribute to energy efficiency has been conducted in order to ensure that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] Since moisture may be mixed into the materials constituting a secondary battery, which may lead to a decrease in charge / discharge performance, it is necessary to control the dew point during the manufacture of secondary batteries. For example, Patent Document 1 describes an air circulation system for manufacturing secondary batteries in which a clean booth that houses a manufacturing device for secondary batteries is provided in a dry room, and the inside of the dry room is dehumidified by a dehumidification unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Korean Patent Publication No. 10-2022-0046333 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, a dehumidifier is operated to maintain a constant low humidity environment inside a dry room in which a secondary battery manufacturing apparatus is installed, so the dehumidifier consumes a lot of power and there is room for improvement in terms of reducing power consumption.

[0006] The present invention provides a method for manufacturing a secondary battery that can reduce the power consumption of a dehumidifier that creates a low dew point environment, thereby contributing to improved energy efficiency. [Means for solving the problem]

[0007] The present invention relates to A method for manufacturing a secondary battery having an electrode laminate in which a positive electrode layer and a negative electrode layer are laminated, and an exterior body that houses the electrode laminate, comprising the steps of: a positive electrode step of forming or storing the positive electrode layer; a negative electrode step of forming or storing the negative electrode layer; a battery assembly process of stacking the positive electrode layer and the negative electrode layer and housing the stacked battery in the exterior body, Based on the dew point required in each process, the dehumidified gas discharged from the dehumidifier is circulated in order from the process with the lowest dew point.

[0008] The present invention also provides a method for producing a semiconductor device comprising the steps of: A method for manufacturing a secondary battery having an electrode laminate in which a positive electrode layer and a negative electrode layer are laminated, and an exterior body that houses the electrode laminate, comprising the steps of: a positive electrode step of forming or storing the positive electrode layer; a negative electrode step of forming or storing the negative electrode layer; a laminate forming step of forming the electrode laminate by laminating the positive electrode layer and the negative electrode layer, and housing the electrode laminate in the exterior body; and a liquid injection step of injecting an electrolyte into the exterior body, The method further includes a drying step, which is performed before the liquid injection step, of introducing a dehumidified gas sent from a dehumidifier into a dry box and drying the electrode stack housed in the exterior body in the dry box. Effect of the Invention

[0009] According to the present invention, it is possible to reduce the power consumption of a dehumidifier that creates a low dew point environment. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is an external perspective view of a secondary battery 10 according to one embodiment of the present invention. [Diagram 2] 1 is a schematic cross-sectional view of a secondary battery 10. FIG. [Diagram 3] FIG. 2 is a block diagram illustrating a method for manufacturing the secondary battery 10. [Figure 4]13 is a schematic diagram for explaining (a) a drying step S122 in a dry box 80, (b) transport from the drying step S122 to a liquid injection step S123, and (c) the liquid injection step S123. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First, a secondary battery according to one embodiment of the present invention will be described.

[0012] [Secondary battery] FIG. 1 is an external perspective view of a secondary battery 10, and FIG. 2 is a schematic cross-sectional view of the secondary battery 10. As shown in FIG.

[0013] The secondary battery 10 includes an electrode laminate 11, a positive electrode tab lead 12 and a negative electrode tab lead 13 extending from both ends of the electrode laminate 11, and an exterior body 14 (e.g., a laminate film) that houses the electrode laminate 11. The electrode laminate 11 includes a positive electrode layer 20 to which the positive electrode tab lead 12 is welded, a negative electrode layer 30 to which the negative electrode tab lead 13 is welded, and a separator 40 disposed between the positive electrode layer 20 and the negative electrode layer 30. Note that, in the example shown in Fig. 2, the electrode laminate 11 is configured with only one layer of the positive electrode layer 20, the separator 40, and the negative electrode layer 30, but a configuration in which a plurality of positive electrode layers 20, separators 40, and negative electrode layers 30 are stacked may also be used.

[0014] The secondary battery 10 is constructed by laminating a positive electrode layer 20, a negative electrode layer 30, and a separator 40, and sealing them together with an electrolyte inside an exterior body 14, and charging and discharging are performed by the exchange of lithium ions between the positive electrode layer 20 and the negative electrode layer 30 via the electrolyte.

[0015] The positive electrode layer 20 includes a positive electrode current collector layer 21 and a positive electrode active material layer 22 which are stacked on top of each other.

[0016] The positive electrode current collector layer 21 is preferably made of at least one material having high electrical conductivity. Examples of the material having high electrical conductivity include metals or alloys containing at least one of the metallic elements silver, palladium, gold, platinum, aluminum, copper, chromium, and nickel, and non-metals such as carbon. In consideration of manufacturing costs in addition to high electrical conductivity, aluminum, nickel, or stainless steel is preferable.

[0017] Examples of the shape of the positive electrode current collector layer 21 include a foil shape, a plate shape, a mesh shape, a nonwoven fabric shape, a foam shape, etc. In order to improve the adhesion with the positive electrode active material layer 22, carbon or the like may be disposed on the surface of the positive electrode current collector layer 21, or the surface may be roughened.

[0018] The positive electrode active material layer 22 contains a positive electrode active material that gives and receives lithium ions and electrons. The positive electrode active material is not particularly limited as long as it can reversibly release and absorb lithium ions and transport electrons. For example, the positive electrode active material is lithium cobalt oxide (LiCoO 2 ) and lithium composite oxides such as lithium-manganese-nickel-cobalt oxide. The positive electrode active material layer 22 may be made of one type of material, or may be made of two or more types of materials. The positive electrode active material layer 22 may further contain a conductive assistant, a binder, and the like.

[0019] The negative electrode layer 30 includes a negative electrode current collector layer 31 and a negative electrode active material layer 32 which are stacked on top of each other.

[0020] The negative electrode current collector layer 31, like the positive electrode current collector layer 21, is preferably composed of at least one substance having high electrical conductivity, such as a metal or alloy containing at least one metallic element selected from the group consisting of silver, palladium, gold, platinum, aluminum, copper, chromium, and nickel, or a non-metal such as carbon.

[0021] Examples of the shape of the negative electrode current collector layer 31 include a foil shape, a plate shape, a mesh shape, a nonwoven fabric shape, a foam shape, etc. In order to improve the adhesion with the negative electrode active material layer 32, carbon or the like may be disposed on the surface of the negative electrode current collector layer 31, or the surface may be roughened.

[0022] The negative electrode active material layer 32 includes a negative electrode active material that gives and receives lithium ions and electrons. The negative electrode active material is not particularly limited as long as it can reversibly release and absorb lithium ions and transport electrons. For example, the negative electrode active material may be metallic lithium, lithium alloys, metal oxides, metal sulfides, metal nitrides, Si, SiO, carbon materials (such as graphite, hard carbon, and soft carbon), and the like. The negative electrode active material may be composed of one type of material, or may be composed of two or more types of materials. The negative electrode active material layer 32 may further include a conductive assistant, a binder, and the like.

[0023] The separator 40 is an insulator made of, for example, a nonwoven fabric of glass fiber or a porous resin film, and is impregnated with an electrolyte. The separator 40 is interposed between the positive electrode layer 20 and the negative electrode layer 30, thereby preventing a short circuit between them. The material constituting the separator 40 is not particularly limited, but examples thereof include polyolefins such as polyethylene and polypropylene, aramid, polyimide, fluororesin, glass fiber, and cellulose fiber. In particular, in the separator 40 having an inorganic particle layer on the separator 40, it is necessary to dry and remove moisture that is re-adsorbed on the surface of the inorganic fine particles, and this is effective in combination with the method for producing a secondary battery of the present invention described later.

[0024] The electrolytic solution is, for example, an organic electrolytic solution in which an electrolyte is dissolved in an organic solvent. The organic solvent may be a cyclic carbonate, a chain carbonate, a cyclic ether, a chain ether, a hydrofluoroether, an aromatic ether, a sulfone, a cyclic ester, a chain carboxylate ester, or a nitrile, and examples of the organic solvent include propylene carbonate, ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, and diethylene glycol dimethyl ether. Examples of the cyclic ether include tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, and 4-methyl1,3-dioxolane. Examples of the chain ether include 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, and diethyl ether. Examples of hydrofluoroethers include 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, bis(2,2,2-trifluoroethyl)ether, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, etc. These organic solvents may be used alone or in combination. Examples of electrolytes include lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, etc. These electrolytes may be used alone or in combination.

[0025] [Secondary battery manufacturing method] Next, regarding a method for manufacturing a secondary battery according to one embodiment of the present invention, first, an outline of the manufacturing method will be described, and then, dew point management during manufacturing will be described.

[0026] (Summary of manufacturing method) 3 is a block diagram illustrating a method for manufacturing a secondary battery. The method for manufacturing a secondary battery 10 of this embodiment includes a positive electrode step S100 for forming or storing a positive electrode layer 20, a negative electrode step S110 for forming or storing a negative electrode layer 30, a battery assembly step S120 for stacking the positive electrode layer 20 and the negative electrode layer 30 and housing them in an exterior body 14, and a chemical formation step S130 for chemically forming the secondary battery 10.

[0027] The positive electrode process S100 includes, for example, a coating process of applying a positive electrode active material to the positive electrode collector layer 21 to form the positive electrode active material layer 22, a pressing process of pressing the stacked positive electrode collector layer 21 and the positive electrode active material layer 22 with a roll press or the like to form the positive electrode layer 20, and a slitting process of cutting the positive electrode layer 20 after the pressing process to a predetermined size. Note that the positive electrode process S100 may include a storage process of storing (including temporary storage) the positive electrode layer 20 after forming the positive electrode layer 20 and before the battery assembly process S120, or storing the procured positive electrode layer 20 when the positive electrode layer 20 is procured separately without providing a process of forming the positive electrode layer 20 in the production line.

[0028] Similarly to the positive electrode process S100, the negative electrode process S110 also includes, for example, a coating process of applying a negative electrode active material to the negative electrode collector layer 31 to form the negative electrode active material layer 32, a pressing process of pressing the laminated negative electrode collector layer 31 and the negative electrode active material layer 32 with a roll press or the like to form the negative electrode layer 30, and a slitting process of cutting the negative electrode layer 30 after the pressing process to a predetermined dimension. Note that the negative electrode process S110 may include a storage process of storing (including temporary storage) the negative electrode layer 30 after molding the negative electrode layer 30 and before the battery assembly process S120, or storing the procured negative electrode layer 30 when the negative electrode layer 30 is procured separately without providing a process of forming the negative electrode layer 30 in the production line.

[0029] The battery assembly process S120 includes a laminate forming process S121 in which the positive electrode layer 20 and the negative electrode layer 30 are laminated to form the electrode laminate 11 and the electrode laminate 11 is housed in an outer casing 14, a drying process S122 in which the electrode laminate 11 housed in the outer casing 14 is dried, and a liquid injection process S123 in which an electrolyte is injected into the outer casing 14.

[0030] The laminate forming process S121 includes, for example, an electrode lamination process in which the positive electrode layer 20 and the negative electrode layer 30 are laminated with a separator 40 interposed therebetween to form the electrode laminate 11, a tab welding process in which the positive electrode tab lead 12 and the negative electrode tab lead 13 are welded to the positive electrode layer 20 and the negative electrode layer 30, respectively, and a housing process in which the electrode laminate 11 is housed in an outer casing 14.

[0031] The drying step S122 is a step of drying the electrode laminate 11 housed in the exterior body 14 in an environment with an extremely low dew point before the liquid injection step S123 is performed. Although details will be described later, in the drying step S122, the electrode laminate 11 is dried by waiting for a predetermined time in the dry box 80 into which the dehumidified air sent out from the dehumidifier 70 is introduced. The inside of the dry box 80 does not include devices and equipment such as a lamination machine, a welding device, and a laminate seal, so that the inside of the dry box 80 can be minimized, and since the gas replacement speed is high, the electrode laminate 11 can be dried in a short residence time. In addition, the dehumidified air in the dry box 80 is preferably higher than room temperature, and the drying time can be shortened by passing dehumidified air at, for example, 30 to 80°C. In addition, it is also possible to further shorten the drying time by flowing low moisture gas such as dry nitrogen or argon into the dry box 80 in addition to the dehumidified air.

[0032] In the liquid injection step S123, the electrolyte is injected into the exterior body 14 in an environment with an extremely low dew point, and the exterior body 14 is sealed. In this embodiment, the liquid injection step S123 is also performed in the dry box 80, similar to the drying step S122. Since the electrode stack 11 is dried in the drying step S122 before the liquid injection step S123, it is possible to prevent moisture from being mixed into the electrolyte. After the liquid injection, the opening of the exterior body 14 is thermally welded and temporarily sealed.

[0033] The chemical conversion step S130 includes, for example, an aging step of leaving the battery for a predetermined time while charging it, etc. After the chemical conversion step S130, the temporarily sealed opening of the exterior body 14 is resealed.

[0034] (Dew point control) If moisture gets mixed into the materials constituting the secondary battery 10 during the manufacture of the secondary battery 10, this may lead to a decrease in the charge / discharge performance of the secondary battery 10, and therefore it is necessary to manage the dew point in each process included in the manufacturing line of the secondary battery 10. Here, the dew point essentially indicates the degree of dryness of the space, and the lower the dew point, the drier the space is, and the higher the dew point, the less dry the space is.

[0035] For example, when manufacturing a lithium ion battery using graphite as the negative electrode active material, the entire manufacturing process is generally performed in an environment with a low dew point (for example, a dew point of -40°C or lower). When manufacturing a lithium metal secondary battery using lithium metal as the negative electrode active material, lithium metal has a high reactivity with water due to its high ionization tendency, so that an environment with an even lower dew point (for example, a dew point of -50°C or lower) is required in the manufacturing process in which the negative electrode layer 30 is exposed.

[0036] The low dew point environment (hereinafter also referred to as low dew point environment) is created by supplying and discharging dehumidified air generated by dehumidifying air to a low dew point by the dehumidifier 70 to the production line for secondary batteries 10. Since the production line is an environment where moisture may always be generated by workers working in each process, the dehumidifier 70 continuously supplies dehumidified air. In addition, the dehumidifier 70 is configured to be able to adjust the volume of the dehumidified air (the amount of dehumidified air passing through per unit time), and adjusts the volume of the air to adjust the dew point of the dehumidified air supplied to the production line. In the production of secondary batteries 10, the operation of the dehumidifier 70 consumes a lot of power.

[0037] To achieve a uniform low dew point environment throughout the entire production line, the volume of the space to which the dehumidified air is supplied is large, so the volume of the dehumidified air sent out from the dehumidifier must be increased, which further increases the power consumption of the dehumidifier. Furthermore, capital investment is required to increase the number of dehumidifiers installed, which further increases the power consumption due to the operation of multiple dehumidifiers. This leads to an increase in the manufacturing cost of the secondary battery 10.

[0038] Therefore, in the manufacturing method of the secondary battery 10 of this embodiment, the dehumidified air sent out from the dehumidifier 70 is circulated in order from the process with the lowest required dew point based on the dew point required in each process. This eliminates the need to create a uniform low dew point environment for all processes in accordance with the process that requires the lowest dew point, thereby reducing power consumption due to the operation of the dehumidifier 70. In addition, an increase in capital investment for the dehumidifier 70 can be suppressed. This allows the manufacturing cost of the secondary battery 10 to be reduced.

[0039] The above-mentioned dew point management will be described in more detail below. In the following description, a specific dew point value will be illustrated using an example in which the secondary battery 10 is a lithium metal secondary battery with high energy density.

[0040] Since the lithium metal secondary battery contains lithium metal, which is highly reactive with water, in the negative electrode active material, the dew point is strictly controlled so that the negative electrode process S110 is a low dew point environment. The positive electrode process S100 does not need to be controlled to a dew point as low as that of the negative electrode process S110, and is controlled at a dew point higher than that of the negative electrode process S110. The battery assembly process S120 is a downstream process in the manufacturing process of the secondary battery 10, and the dew point is controlled even more strictly so that the dew point is lower than that of the negative electrode process S110 so that moisture is not mixed in immediately before the assembly of the secondary battery 10 is completed. That is, the battery assembly process S120, the negative electrode process S110, and the positive electrode process S100 require low dew points in this order.

[0041] Therefore, the dehumidifier 70 circulates the dehumidified air in the order of the battery assembly process S120, the anode process S110, and the cathode process S100. At this time, the dew point of the dehumidified air is lowest in the battery assembly process S120, which is closer to the dehumidifier 70, and gradually increases in the order of the anode process S110 and the cathode process S100. By circulating the dehumidified air in this order, the dew point required in each process can be satisfied without creating a uniform low dew point environment for all processes, so that the power consumption due to the operation of the dehumidifier 70 can be reduced.

[0042] More specifically, the dehumidifier 70 distributes the dehumidified air from the drying step S122 and the liquid injection step S123 of the manufacturing process.

[0043] The production line for the secondary battery 10 is provided with a plurality of pipes (not shown) through which the dehumidified air sent out from the dehumidifier 70 flows. The plurality of pipes are provided between the air outlet of the dehumidifier 70 and the dry box 80 (i.e., the space where the drying step S122 and the liquid injection step S123 are performed), between the dry box 80 and the space 91 where the negative electrode step S110 and the laminate forming step S121 are performed, between the space 91 and the space 92 where the positive electrode step S100 is performed, and between the space 92 and the air intake of the dehumidifier 70.

[0044] The dehumidified air generated by the dehumidifier 70 has a dew point of, for example, -80°C, and the moisture content of this dehumidified air is 1 ppm or less. When this dehumidified air is supplied to the dry box 80, the dew point of the dry box 80 becomes, for example, -60°C or less, creating an extremely low dew point environment. This satisfies the dew point required in the drying step S122 and the liquid injection step S123.

[0045] The dew point of the dehumidified air exhausted from the dry box 80 and supplied to the space 91 where the anode process S110 and the laminate forming process S121 are performed is approximately the same as the dew point inside the dry box 80, for example, −60° C. When this dehumidified air is supplied to the space 91, the dew point of the space 91 becomes, for example, −60° C. to −50° C. Although the dew point of the space 91 is higher than that of the dry box 80, a low dew point environment is required because the anode process S110 and the laminate forming process S121 are performed in a state where the anode layer 30 is exposed (i.e., the anode layer 30 is not sealed in the exterior body 14). This satisfies the dew point required for the anode process S110 and the laminate forming process S121.

[0046] The dew point of the dehumidified air exhausted from the space 91 and introduced into the space 92 where the positive electrode step S100 is performed is approximately the same as the dew point of the space 91, for example, −50° C. When this dehumidified air is supplied to the space 92, the dew point of the space 92 becomes, for example, −50° C. to −40° C. This satisfies the dew point required in the positive electrode step S100.

[0047] The dehumidified air (e.g., with a dew point of −40° C.) exhausted from the space 92 is introduced into the dehumidifier 70, where it is dehumidified until the dew point becomes −80° C., and then is supplied again to the dry box 80. The dehumidifier 70 circulates the dehumidified air in a direction from the downstream side to the upstream side of the production line for the secondary batteries 10.

[0048] 4 is a schematic diagram for explaining the dry box 80. The dry box 80 is a local space where people do not enter or exit, and prevents moisture generated from the human body from entering the electrode stack 11.

[0049] The dry box 80 has a first space 81 and a second space 82 separated by an openable / closable shutter 83. The second space 82 is located downstream in the production line from the first space 81. Although the first space 81 and the second space 82 are separated by the shutter 83, dehumidified air is introduced into each space from the dehumidifier 70, and the dew points are approximately the same.

[0050] After the laminate forming step S121, the electrode laminate 11 housed in the exterior body 14 is transported to the first space 81, and a drying step S122 is performed in the first space 81 (FIG. 4(a)). In the drying step S122, the dew point and drying time of the first space 81 are controlled so as to remove as much moisture as possible from the electrode laminate 11 before the liquid injection step S123.

[0051] As described above, the dew point of the first space 81 is −60° C. or less, and the drying time is, for example, 1 minute or more and 72 hours or less. More specifically, the drying time is adjusted according to the dew point of the first space 81. For example, when the dew point of the first space 81 is −70° C., the electrode stack 11 can be sufficiently dried by setting the drying time to 3 hours. In this embodiment, a low dew point environment is formed not only in the drying step S122 but also in the steps upstream of the drying step S122 (the positive electrode step S100, the negative electrode step S110, and the stack forming step S121), so that the drying time in the drying step S122 can be shortened and the power consumption of the dehumidifier 70 can be reduced.

[0052] After the drying step S122, the shutter 83 opens, and the electrode stack 11 housed in the exterior body 14 is transported from the first space 81 to the second space 82 (FIG. 4(b)). After the electrode stack 11 is transported to the second space 82, the shutter 83 closes. Although not shown in the figure, after the electrode stack 11 is transported from the first space 81 to the second space 82, a new electrode stack 11 is transported to the first space 81, and the drying step S122 is performed on this electrode stack 11.

[0053] In the second space 82, the liquid injection step S123 is performed (FIG. 4(c)). The liquid injection step S123 is also performed in an environment with an extremely low dew point, similar to the drying step S122. In this manner, in the dry box 80, the drying step S122 and the liquid injection step S123 are performed continuously.

[0054] When the secondary battery 10 is a lithium metal secondary battery, a non-water-soluble organic electrolyte is injected into the exterior body 14. The moisture content of the electrolyte at this time is, for example, 50 ppm or less, and an electrolyte with an extremely low moisture content is injected.

[0055] After the liquid injection step S123, the exterior body 14 is temporarily sealed in the second space 82 by heat welding or the like. This seals the electrode stack 11 and the electrolyte inside the exterior body 14, and moisture does not penetrate into the electrode stack 11 and the electrolyte, making dew point management unnecessary in the subsequent step (i.e., the chemical conversion step S130).

[0056] The dew point control in the manufacturing method of the secondary battery 10 described above can be applied to any of the secondary battery 10, that is, a liquid battery including a liquid electrolyte, a semi-solid battery including a semi-solid electrolyte, and an all-solid battery including a solid electrolyte.

[0057] When the secondary battery 10 is a semi-solid battery, in the above-mentioned liquid injection step S123, a semi-solid electrolyte is injected into the exterior body 14. Here, the semi-solid electrolyte is an electrolyte that is a mixture of a liquid phase and a solid phase, such as a slurry, a particle suspension, a colloidal suspension, an emulsion, a gel, or a micelle.

[0058] When the secondary battery 10 is an all-solid-state battery, the electrode laminate 11 of the secondary battery 10 includes a solid electrolyte layer or the like provided between the positive electrode layer 20 and the negative electrode layer 30, instead of the separator 40. The above-mentioned liquid injection step S123 is omitted, and the exterior body 14 is sealed after the drying step S122.

[0059] Although one embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present invention. In addition, the components in the above embodiment may be arbitrarily combined within the scope of the invention.

[0060] For example, when the secondary battery 10 is a lithium metal secondary battery, the surface of the negative electrode layer 30 containing metallic lithium is provided with lithium carbonate (Li 2 CO 3) may be formed. In this way, by forming a passivated layer on the surface of the negative electrode layer 30, it is possible to further suppress the reaction of metallic lithium with moisture. By modifying the surface of the lithium metal negative electrode, the reaction with moisture can be reduced, so that water is less likely to react with lithium and is in an adsorbed state. This allows moisture to be removed more quickly. In this case, the residence time of the electrode stack 11 in the low dew point dry box 80 can be shortened, and the production speed of the secondary battery 10 can be further increased.

[0061] In the above-described embodiment, dew point management has been described using an example in which the secondary battery 10 is a lithium metal secondary battery. However, the secondary battery 10 is not limited to a lithium metal secondary battery, and the dew point management can be applied to various types of batteries.

[0062] This specification describes at least the following items. In parentheses, components corresponding to the above-described embodiment are shown as examples, but the present invention is not limited to these.

[0063] (1) A method for manufacturing a secondary battery (secondary battery 10) having an electrode laminate (electrode laminate 11) in which a positive electrode layer (positive electrode layer 20) and a negative electrode layer (negative electrode layer 30) are laminated, and an exterior body (exterior body 14) that houses the electrode laminate, comprising: A positive electrode step (positive electrode step S100) of forming or storing the positive electrode layer; A negative electrode step (negative electrode step S110) of forming or storing the negative electrode layer; A battery assembly process (battery assembly process S120) of stacking the positive electrode layer and the negative electrode layer and housing them in the exterior body, Based on the dew point required for each process, the dehumidified gas discharged from the dehumidifier (dehumidifier 70) is circulated in order from the process with the lowest dew point. A method for manufacturing a secondary battery.

[0064] According to (1), the dehumidifier is circulated in order from the process with the lowest dew point based on the dew point required for each process, so that the power consumption due to the operation of the dehumidifier can be reduced compared to the case where a uniform low dew point environment is realized in all processes during the production of secondary batteries, and therefore the production cost of secondary batteries can be reduced.

[0065] (2) A method for producing the secondary battery according to (1), comprising the steps of: The battery assembly process, the negative electrode process, and the positive electrode process require low dew points in this order, The dehumidified gas discharged from the dehumidifier is circulated in the order of the battery assembly process, the negative electrode process, and the positive electrode process. A method for manufacturing a secondary battery.

[0066] According to (2), since the dehumidifier is circulated from the battery assembly process, which is close to the downstream side in the manufacturing process, it is possible to prevent moisture from being mixed in just before the completion of the secondary battery. Also, since the dehumidifier is circulated preferentially to the negative electrode process, where the negative electrode layer, which is highly reactive with water, is exposed and a low dew point is required, rather than the positive electrode process, it is possible to prevent moisture from being mixed in the negative electrode layer.

[0067] (3) A method for producing a secondary battery according to (2), comprising the steps of: The battery assembly process includes: a laminate forming step (laminate forming step S121) of forming the electrode laminate by laminating the positive electrode layer and the negative electrode layer, and housing the electrode laminate in the exterior body; A drying step (drying step S122) of drying the electrode stack housed in the outer casing in a dry box (dry box 80), The drying step requires the lowest dew point, The dehumidified gas discharged from the dehumidifier is circulated through the drying process. A method for manufacturing a secondary battery.

[0068] According to (3), by drying the electrode laminate locally in a dry box in the drying process near the downstream side in the manufacturing process, it is possible to more reliably prevent moisture from being mixed into the electrode laminate. In addition, since the dew point gradually decreases toward the downstream side in the manufacturing process, it is possible to shorten the drying time in the drying process and further reduce the power consumption of the dehumidifier.

[0069] (4) A method for producing a secondary battery according to (3), comprising the steps of: The battery assembly process further includes a liquid injection process (liquid injection process S123) of injecting an electrolyte into the exterior body after the drying process, The liquid injection step is carried out in the dry box. A method for manufacturing a secondary battery.

[0070] According to (4), since the drying step is performed before the liquid injection step, it is possible to prevent moisture from being mixed into the electrolyte.

[0071] (5) A method for producing a secondary battery according to (4), comprising the steps of: The dry box has a first space (first space 81) and a second space (second space 82) partitioned by an openable / closable member (shutter 83), The drying step is performed in the first space with the opening / closing member closed, After the drying step, the opening and closing member is opened, and the electrode stack housed in the outer casing is transported from the first space to the second space, The liquid pouring step is performed in the second space with the opening / closing member closed. A method for manufacturing a secondary battery.

[0072] According to (5), the drying step and the liquid injection step can be carried out continuously in a dry box.

[0073] (6) A method for producing a secondary battery according to (4) or (5), comprising the steps of: The moisture content of the electrolyte injected into the exterior body in the injection step is 50 ppm or less. A method for manufacturing a secondary battery.

[0074] According to (6), an electrolyte with an extremely low water content is injected into the exterior body in the injection step.

[0075] (7) A method for producing a secondary battery according to any one of (3) to (6), comprising the steps of: In the drying step, the electrode stack housed in the exterior body is dried at a predetermined dew point for a predetermined time. A method for manufacturing a secondary battery.

[0076] According to (7), by controlling the dew point and drying time in the drying step, it is possible to more reliably prevent moisture from being mixed into the electrode laminate.

[0077] (8) A method for producing a secondary battery according to (7), comprising the steps of: The predetermined dew point is −60° C. or less; A method for manufacturing a secondary battery.

[0078] According to (8), the electrode laminate is locally dried in an environment with an extremely low dew point, so that infiltration of moisture into the electrode laminate can be more reliably prevented, and the adsorbed moisture is desorbed in a short period of time.

[0079] (9) A method for producing a secondary battery according to (7) or (8), comprising the steps of: The predetermined time is at least 1 minute and at most 72 hours. A method for manufacturing a secondary battery.

[0080] According to (9), since the drying process is short, the power consumption of the dehumidifier can be significantly reduced.

[0081] (10) A method for producing a secondary battery according to any one of (3) to (9), comprising the steps of: The dehumidifier introduced into the dry box has a moisture content of 1 ppm or less. A method for manufacturing a secondary battery.

[0082] According to (10), since the electrode stack is locally dried in an environment with an extremely low dew point, it is possible to more reliably prevent moisture from being mixed into the electrode stack.

[0083] (11) A method for producing a secondary battery according to any one of (3) to (10), comprising the steps of: The dry box is a space where no one enters or exits. A method for manufacturing a secondary battery.

[0084] According to (11), moisture generated from the human body can be prevented from entering the dry box, and the inside of the dry box can be kept in an extremely low dew point environment.

[0085] (12) A method for producing a secondary battery according to any one of (1) to (11), comprising the steps of: The secondary battery is a lithium metal secondary battery in which the negative electrode active material of the negative electrode layer contains lithium metal. A method for manufacturing a secondary battery.

[0086] According to (12), even when the negative electrode active material contains lithium metal, which is highly reactive with moisture, and an extremely low dew point environment is required, the power consumption and the number of dehumidifiers installed can be reduced, and the manufacturing cost of the secondary battery can be reduced.

[0087] (13) A method for producing a secondary battery according to (12), comprising the steps of: A passivation layer containing lithium carbonate is formed on the surface of the negative electrode layer. A method for manufacturing a secondary battery.

[0088] According to (13), in a lithium metal secondary battery, the water reaction in the negative electrode layer can be suppressed.

[0089] (14) A method for manufacturing a secondary battery (secondary battery 10) having an electrode laminate (electrode laminate 11) in which a positive electrode layer (positive electrode layer 20) and a negative electrode layer (negative electrode layer 30) are laminated, and an exterior body (exterior body 14) that houses the electrode laminate, comprising: A positive electrode step (positive electrode step S100) of forming or storing the positive electrode layer; A negative electrode step (negative electrode step S110) of forming or storing the negative electrode layer; a laminate forming step (laminate forming step S121) of forming the electrode laminate by laminating the positive electrode layer and the negative electrode layer, and housing the electrode laminate in the exterior body; A liquid injection step (liquid injection step S123) of injecting an electrolyte into the exterior body, The method further includes a drying step (drying step S122) of introducing a dehumidified gas sent from a dehumidifier (dehumidifier 70) into a dry box (dry box 80) before the liquid injection step, and drying the electrode stack housed in the exterior body in the dry box. A method for manufacturing a secondary battery.

[0090] According to (14), by locally drying the electrode stack in a dry box in the drying step near the downstream side in the manufacturing process, it is possible to more reliably prevent moisture from being mixed into the electrode stack. In addition, since the drying step is performed before the liquid injection step, it is possible to prevent moisture from being mixed into the electrolyte. [Explanation of symbols]

[0091] 10 Secondary battery 11 Electrode laminate 14 Exterior body 20 Positive electrode layer 30 Negative electrode layer 70 Dehumidifier 80 Dry Box 81 1st space 82 Second space 83 Shutter (opening and closing parts) S100 Positive electrode process S110 Negative electrode process S120 Battery assembly process S121 Laminated body molding process S122 Drying process S123 Liquid injection process

Claims

1. A method for manufacturing a secondary battery having an electrode laminate in which a positive electrode layer and a negative electrode layer are laminated, and an exterior body that houses the electrode laminate, comprising the steps of: a positive electrode step of forming or storing the positive electrode layer; a negative electrode step of forming or storing the negative electrode layer; a battery assembly process of stacking the positive electrode layer and the negative electrode layer and housing the stacked battery in the exterior body, Based on the dew point required for each process, the dehumidified gas discharged from the dehumidifier is circulated in order from the process with the lowest dew point. A method for manufacturing a secondary battery.

2. A method for producing the secondary battery according to claim 1, comprising the steps of: The battery assembly process, the negative electrode process, and the positive electrode process require low dew points in this order, The dehumidified gas discharged from the dehumidifier is circulated in the order of the battery assembly process, the negative electrode process, and the positive electrode process. A method for manufacturing a secondary battery.

3. A method for producing a secondary battery according to claim 2, comprising the steps of: The battery assembly process includes: a laminate forming step of forming the electrode laminate by laminating the positive electrode layer and the negative electrode layer, and housing the electrode laminate in the exterior body; A drying step of drying the electrode stack housed in the outer casing in a dry box, The drying step requires the lowest dew point, The dehumidified gas discharged from the dehumidifier is circulated through the drying process. A method for manufacturing a secondary battery.

4. A method for producing a secondary battery according to claim 3, comprising the steps of: the battery assembly process further includes a liquid injection process of injecting an electrolyte into the exterior body after the drying process, The liquid injection step is carried out in the dry box. A method for manufacturing a secondary battery.

5. A method for producing a secondary battery according to claim 4, comprising the steps of: The dry box has a first space and a second space partitioned by an openable / closable member, The drying step is performed in the first space with the opening / closing member closed, After the drying step, the opening / closing member is opened, and the electrode stack housed in the outer casing is transported from the first space to the second space, The liquid pouring step is performed in the second space with the opening / closing member closed. A method for manufacturing a secondary battery.

6. A method for producing a secondary battery according to claim 4, comprising the steps of: The moisture content of the electrolyte injected into the exterior body in the injection step is 50 ppm or less. A method for manufacturing a secondary battery.

7. A method for producing a secondary battery according to claim 3, comprising the steps of: In the drying step, the electrode stack housed in the exterior body is dried at a predetermined dew point for a predetermined time. A method for manufacturing a secondary battery.

8. A method for producing a secondary battery according to claim 7, comprising the steps of: The predetermined dew point is −60° C. or lower. A method for manufacturing a secondary battery.

9. A method for producing a secondary battery according to claim 7, comprising the steps of: The predetermined time is greater than or equal to 1 minute and less than or equal to 72 hours. A method for manufacturing a secondary battery.

10. A method for producing a secondary battery according to claim 3, comprising the steps of: The dehumidifying material introduced into the dry box has a moisture content of 1 ppm or less. A method for manufacturing a secondary battery.

11. A method for producing a secondary battery according to claim 3, comprising the steps of: The dry box is a space where no one enters or exits. A method for manufacturing a secondary battery.

12. A method for producing the secondary battery according to any one of claims 1 to 11, comprising the steps of: The secondary battery is a lithium metal secondary battery in which the negative electrode active material of the negative electrode layer contains lithium metal. A method for manufacturing a secondary battery.

13. A method for producing a secondary battery according to claim 12, comprising the steps of: A passivation layer containing lithium carbonate is formed on the surface of the negative electrode layer. A method for manufacturing a secondary battery.

14. A method for manufacturing a secondary battery having an electrode laminate in which a positive electrode layer and a negative electrode layer are laminated, and an exterior body that houses the electrode laminate, comprising the steps of: a positive electrode step of forming or storing the positive electrode layer; a negative electrode step of forming or storing the negative electrode layer; a laminate forming step of forming the electrode laminate by laminating the positive electrode layer and the negative electrode layer, and housing the electrode laminate in the exterior body; and a liquid injection step of injecting an electrolyte into the exterior body, The method further includes a drying step of introducing a dehumidified gas sent from a dehumidifier into a dry box and drying the electrode stack housed in the exterior body in the dry box before the liquid injection step. A method for manufacturing a secondary battery.

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