Method for manufacturing an electrochemical cell

Abstract

To provide an electrochemical cell and a method for manufacturing the electrochemical cell that can further increase the degree of freedom in material selection in battery design.SOLUTION: In a manufacturing method of an electrochemical cell 1 includes a solid electrolyte layer 7, a positive electrode layer 5 located on one side of the solid electrolyte layer 7, and a negative electrode layer 6 located on the other side of the solid electrolyte layer 7, and a laminate of a positive electrode layer precursor in which a first porous body is impregnated with a positive electrode slurry containing a positive electrode active material and a solid electrolyte layer 7 is fired to form a first laminate in which the positive electrode layer 5 and solid electrolyte layer 7 are bonded.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an electrochemical cell and an electrochemical cell. [Background technology]

[0002] All-solid-state batteries (electrochemical cells) that use a solid electrolyte made of an inorganic material instead of the electrolyte solution of lithium-ion secondary batteries or a gel electrolyte in which the electrolyte solution is held in a polymer are known. In all-solid-state batteries, contact resistance between inorganic materials increases the internal resistance of the solid electrolyte, resulting in reduced battery performance.

[0003] To address these problems, for example, Patent Document 1 proposes an all-solid-state battery that is composed of a composite of a porous solid electrolyte that exhibits specific lithium ion conductivity and a battery active material that is filled into the pores of the porous solid electrolyte. The invention of Patent Document 1 aims to improve battery performance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-260887 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the invention of Patent Document 1 uses a porous solid electrolyte, which has the problem of limiting the material options.

[0006] Therefore, an object of the present invention is to provide an electrochemical cell and a method for manufacturing the electrochemical cell that allow greater freedom in material selection in battery design. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following aspects. A method for manufacturing an electrochemical cell according to the present invention is a method for manufacturing an electrochemical cell having a solid electrolyte layer, a positive electrode layer located on one surface of the solid electrolyte layer, and an negative electrode layer located on the other surface of the solid electrolyte layer, wherein the negative electrode active material constituting the negative electrode layer is metallic lithium, the method comprising the steps of: laminating a positive electrode layer precursor, which is obtained by impregnating a first porous body with a positive electrode slurry containing the positive electrode active material, on one surface of the solid electrolyte layer; firing the resulting material to bond the positive electrode layer to one surface of the solid electrolyte layer; laminating the negative electrode layer on the other surface of the solid electrolyte layer; and applying pressure to the negative electrode layer in the thickness direction of the solid electrolyte layer to bond the negative electrode layer to the solid electrolyte layer.

[0008] According to this configuration, the positive electrode layer and the solid electrolyte layer can be easily joined together regardless of the type of the solid electrolyte layer. In addition, this configuration eliminates the need for steps such as sol preparation and gelation, as is required in conventional sol-gel methods, and therefore allows for significant reductions in the time and cost required for production. Furthermore, this configuration allows the energy density of the electrochemical cell to be further increased.

[0010] Furthermore, the present invention provides a method for producing an electrochemical cell having a solid electrolyte layer, a positive electrode layer located on one surface of the solid electrolyte layer, and an negative electrode layer located on the other surface of the solid electrolyte layer, the method comprising firing a laminate of a positive electrode layer precursor obtained by impregnating a first porous body with a positive electrode slurry containing a positive electrode active material, an negative electrode layer precursor obtained by impregnating a second porous body with a negative electrode slurry containing a negative electrode active material, and the solid electrolyte layer to form a second laminate in which the positive electrode layer, the solid electrolyte layer, and the negative electrode layer are bonded together.

[0011] According to this configuration, the positive electrode layer, the solid electrolyte layer, and the negative electrode layer can be easily joined together regardless of the type of the solid electrolyte layer. In addition, this configuration eliminates the need for steps such as sol preparation and gelation, as is required in conventional sol-gel methods, and therefore allows for significant reductions in the time and cost required for production.

[0012] The solid electrolyte layer does not have to be porous. This configuration can more reliably prevent the positive electrode active material and the negative electrode active material from mixing, thereby further improving the battery performance of the electrochemical cell.

[0013] The solid electrolyte constituting the solid electrolyte layer may contain a garnet-type oxide represented by the following formula (1). Li-La-M'-M”-O ···(1) [In formula (1), M′ and M″ represent one or more elements selected from Zr, Nb, Ta, Ga, and Ba.] This configuration makes it possible to further increase the energy density of the electrochemical cell, and also to further increase the stability of the electrical characteristics of the electrochemical cell.

[0014] The first porous body may contain at least one selected from the group consisting of a Nasicon-type oxide represented by the following formula (2) and a Perovskite-type oxide represented by the following formula (3). Li 1+y Al y Ti 2-y (PO4)3···(2) Li 3x La 2 / 3-x TiO3 (3) [In formula (2), y is a number from 0.05 to 0.6. In formula (3), x is a number from 0.033 to 0.17.] This configuration allows the energy density of the electrochemical cell to be further increased. [Effects of the Invention]

[0023] The electrochemical cell manufacturing method and the electrochemical cell of the present invention allow for greater freedom in material selection in battery design. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a cross-sectional view of an electrochemical cell according to one embodiment of the present invention. [Figure 2] 1 is a schematic diagram of a porous body according to one embodiment of the present invention. [Figure 3] 1 is an example of a flowchart of a method for manufacturing an electrochemical cell according to a first embodiment of the present invention. [Figure 4] 1 is an example of a flowchart of a method for manufacturing an electrochemical cell according to a first embodiment of the present invention. [Figure 5] 10 is a flowchart illustrating an example of a method for manufacturing an electrochemical cell according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of an electrochemical cell according to the present invention will be described with reference to the drawings. In the following embodiments, a coin-type all-solid-state battery (hereinafter simply referred to as a "battery") will be taken as an example of an electrochemical cell, and the configuration of this battery will be described. The all-solid-state battery of this embodiment is not limited to a coin type, and may be in various container forms such as a chip type, a laminate type, a square type, a cylindrical type, etc. In addition, in the drawings used in the following description, the scale of each component is appropriately changed and displayed so that each component can be recognized.

[0026] Electrochemical Cell As shown in FIG. 1, the battery (electrochemical cell) 1 of this embodiment includes a so-called coin-shaped exterior body 2, an electrode body 3 housed inside the exterior body 2, and a gasket 30 for sealing the exterior body 2. The exterior body 2 has a cylindrical positive electrode can 10 with a bottom, and a cylindrical negative electrode can 20 with a lid that is fixed to the opening of the positive electrode can 10 via a gasket 30 and forms a storage space between the positive electrode can 10 and the negative electrode can 20. The periphery of the opening of the positive electrode can 10 is crimped to the negative electrode can 20 side to seal the opening, thereby forming the exterior body 2.

[0027] The positive electrode can 10 and the negative electrode can 20 are made of metal and function as a positive electrode terminal and a negative electrode terminal by being electrically connected to the electrode assembly 3, respectively. The material of the positive electrode can 10 can be any conventionally known material without any limitations, such as known stainless steels such as SUS316L and SUS329J4L, or metal materials other than stainless steel. The material of the negative electrode can 20, like the material of the positive electrode can 10, can be any conventionally known material without any limitations, such as known stainless steels such as SUS316L, SUS329J4L, and SUS304, or metal materials other than stainless steel. The material of the negative electrode can 20 may also be a clad material, such as stainless steel pressure-welded with copper, nickel, or the like.

[0028] The electrode assembly 3 has a positive electrode layer 5 located on one surface of a solid electrolyte layer 7 and a negative electrode layer 6 located on the other surface of the solid electrolyte layer 7. The solid electrolyte layer 7 contains a solid electrolyte. The positive electrode layer 5 contains a positive electrode active material. The negative electrode layer 6 contains a negative electrode active material. The positive electrode layer 5 is electrically connected to a positive electrode can 10, and the negative electrode layer 6 is electrically connected to a negative electrode can 20. The positive electrode layer 5 and the solid electrolyte layer 7 are integrated by a process described below and housed inside the exterior body 2.

[0029] 2 is a schematic diagram of the positive electrode layer 5 of this embodiment. The positive electrode layer 5 has a first porous body 51 formed in a flat cylindrical shape (pellet shape) and a positive electrode active material 52 supported inside pores 51a of the first porous body 51. Thickness T of the first porous body 51 51 is, for example, preferably 100 to 1000 μm, more preferably 200 to 900 μm, and even more preferably 300 to 800 μm. 51 When the thickness T is equal to or greater than the lower limit, the electrical capacity of the battery 1 can be further increased. 51 When is equal to or less than the upper limit, the thickness of the battery 1 can be made thinner.

[0030] The major diameter D of the pores 51a of the first porous body 51 51a The major diameter D of the hole 51a is preferably 0.01 to 10 μm, more preferably 0.1 to 8 μm, and even more preferably 1 to 6 μm.51a When the diameter D of the hole 51a is equal to or larger than the lower limit, the hole 51a can be more easily impregnated with the positive electrode slurry. 51a When is equal to or less than the upper limit, the strength of the first porous body 51 can be further increased. The major diameter D of the pores 51a of the first porous body 51 51a can be measured by observing with a microscope or the like. 51a " refers to the maximum diameter of the opening of one hole 51a.

[0031] Examples of the first porous body 51 include a Nasicon-type oxide represented by the following formula (2) and a Perovskite-type oxide represented by the following formula (3). Li 1+y Al y Ti 2-y (PO4)3···(2) Li 3x La 2 / 3-x TiO3 (3) In formula (2), y is a number from 0.05 to 0.6, and in formula (3), x is a number from 0.033 to 0.17. When the first porous body 51 is made of the above oxide, high conductivity of lithium ions can be maintained, and the positive electrode active material 52 can be supported more stably. The first porous body 51 may be used alone or in combination of two or more kinds.

[0032] The first porous body 51 can be produced by, for example, a sol-gel method. Specifically, the first porous body 51 can be produced by depositing polymer particles such as polystyrene or polymethyl methacrylate (PMMA) resin on a substrate, filling this deposit with a sol that is a precursor of the first porous body 51, gelling the sol, and then baking and removing the polymer particles. Alternatively, the first porous body 51 can be produced by a method other than the sol-gel method, for example, forming a deposit containing pore-forming agent particles and electrolyte particles on a support, and then heating the resulting deposit to remove the pore-forming agent particles.

[0033] As the positive electrode active material 52, known materials used in all-solid-state batteries can be utilized. Examples of the positive electrode active material 52 include a single-component positive electrode material, a two-component positive electrode material, a three-component positive electrode material, and the like. Examples of the single-component positive electrode material include LiMO2 (where M represents a metal element such as Co, Ni, Mn, Al, Fe, etc.). Examples of the two-component positive electrode material include Li 1-x CoMnO4 (where x is a number satisfying 0 < x < 1), Li x FePO4 (where x is a number satisfying 0 < x ≤ 1), Li x V6O 13 (where x is a number satisfying 0 < x ≤ 1), Li 1-x Mn2O4 (where x is a number satisfying 0 < x < 1), Li 1-x Ni 0.5 Mn 1.5 O4 (where x is a number satisfying 0 < x < 1), and the like. Examples of the three-component positive electrode material include LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, and the like. These positive electrode active materials 52 may be used alone or in combination of two or more. These positive electrode active materials 52 are supported inside the pores 51a of the first porous body 51. <00​​​​​​​​​​​

[0036] 2 can be interpreted as a schematic diagram of the negative electrode layer 6 of this embodiment. As shown in FIG. A known material used in all-solid-state batteries can be used as the negative electrode active material 62. Various materials can be used as the negative electrode active material 62, for example, carbon materials such as graphite, metals such as Si and Sn or oxides thereof, and metallic lithium.

[0037] When the negative electrode active material 62 is a material used in powder form, such as a carbon material or a metal oxide, it is supported inside the pores 61a of the pellet-shaped second porous body 61, similar to the positive electrode layer 5. In this case, the above-mentioned conductive additive and binder may also be placed inside the pores 61a, if necessary. The second porous body 61 may be made of the same material as the above-mentioned first porous body 51.

[0038] When the negative electrode active material 62 is a metal, it is used in the form of a circularly punched sheet, a disk, or a pellet. In particular, when the negative electrode layer 6 (negative electrode active material 62) is metallic lithium, the energy density of the battery can be improved.

[0039] The solid electrolyte contained in the solid electrolyte layer 7 may be, for example, a garnet-type oxide represented by the following formula (1). Li-La-M'-M”-O ···(1) In formula (1), M′ and M″ represent one or more elements selected from Zr, Nb, Ta, Ga, and Ba. Among these, lithium lanthanum zirconate (LLZ, Li7La3Zr2O 12 When LLZ is used as the solid electrolyte, high conductivity of lithium ions can be maintained, and chemical stability with respect to metallic lithium contained in the negative electrode layer 6 can be further improved.

[0040] It is preferable that the solid electrolyte layer 7 is not porous (non-porous). If the solid electrolyte layer 7 is not porous, mixing of the positive electrode active material 52 and the negative electrode active material 62 can be more reliably suppressed. This further improves the battery performance of the electrochemical cell 1. In this specification, "porous" refers to the property of having a large number of pores, and "non-porous" refers to the property of not having pores, i.e., being dense.

[0041] The solid electrolyte layer 7 may be a porous body. When the solid electrolyte layer 7 is a porous body, the porous body may be made of, for example, the same material as the first porous body 51 or the second porous body 61 described above. In addition to a porous body, a non-porous body can be applied to the solid electrolyte layer 7 of this embodiment, which increases the degree of freedom in material selection in battery design.

[0042] The electrode body 3 of this embodiment has a structure in which a pair of a positive electrode layer 5 and a negative electrode layer 6 are stacked with a solid electrolyte layer 7 interposed therebetween. However, the electrode body is not limited to the above structure. For example, the electrode body may be configured such that a positive electrode layer 5 formed on a metal foil and a negative electrode layer 6 formed on a metal foil are integrated by a method such as laminating, folding, or rolling, with a solid electrolyte layer 7 interposed between them, and then housed inside an exterior body 2.

[0043] <Electrochemical cell manufacturing method> The method for producing an electrochemical cell of the present invention includes the steps of bringing a cathode slurry containing a cathode active material into contact with a first porous body to obtain a cathode layer precursor, and firing the cathode layer precursor and the solid electrolyte layer to bond them together, thereby forming the cathode layer. The method for manufacturing an electrochemical cell according to this embodiment will be described in detail below with reference to the drawings.

[0044] 3, the method for manufacturing an electrochemical cell of this embodiment includes a step (S11) of preparing a positive electrode slurry, a step (S12) of impregnating a first porous body 51 with the positive electrode slurry to prepare a positive electrode layer precursor, a step (S13) of stacking the positive electrode layer precursor on one surface of a solid electrolyte layer 7, and a step (S14) of firing the stack of the positive electrode layer precursor and the solid electrolyte layer 7. Through steps S11 to S14, a first stack in which the positive electrode layer 5 and the solid electrolyte layer 7 are bonded together is obtained.

[0045] In the step (S11) of preparing a positive electrode slurry, the positive electrode active material 52, a binder, and an organic solvent are mixed together to prepare the positive electrode slurry. At this time, a conductive additive may be further mixed in, if necessary. The positive electrode active material 52, the binder, and the conductive additive may be the same materials as those mentioned above.

[0046] Examples of the organic solvent include alcohols and ketones. Examples of alcohols include 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol. Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone.

[0047] The mixer used to mix the positive electrode active material 52, the binder, and the organic solvent may be, for example, a blender or a stirrer, and these mixers can be used to mix the materials uniformly. The mixing time (mixing time) is, for example, preferably 10 to 24 hours, more preferably 12 to 18 hours. When the mixing time is equal to or greater than the above lower limit, a sufficiently uniform positive electrode slurry can be obtained. When the mixing time is equal to or less than the above upper limit, productivity can be further improved.

[0048] The viscosity of the positive electrode slurry at 25°C is, for example, preferably 1000 to 10000 mPa·s, more preferably 3000 to 9000 mPa·s, and even more preferably 4000 to 8000 mPa·s. When the viscosity of the positive electrode slurry at 25°C is equal to or greater than the above lower limit, the positive electrode slurry can be more easily solidified. When the viscosity of the positive electrode slurry at 25°C is equal to or less than the above upper limit, the positive electrode slurry can be more easily impregnated into the first porous body 51. The viscosity of the positive electrode slurry at 25°C can be determined, for example, by adjusting the temperature of the measurement object to 25°C, using a B-type viscometer at a rotation speed of 2000 rpm, and reading the value 60 seconds after the rotor starts to rotate.

[0049] The content of the positive electrode active material 52 in the positive electrode slurry is, for example, preferably 10 to 50 mass %, more preferably 15 to 40 mass %, and even more preferably 20 to 30 mass %, relative to the total mass of the positive electrode slurry. When the content of the positive electrode active material 52 is equal to or greater than the above lower limit, the electric capacity can be further increased. When the content of the positive electrode active material 52 is equal to or less than the above upper limit, the viscosity of the positive electrode slurry can be reduced, and the positive electrode active material 52 can be more easily impregnated into the first porous body 51.

[0050] The content of the binder in the positive electrode slurry is, for example, preferably 5 to 30 mass %, more preferably 10 to 25 mass %, and even more preferably 15 to 20 mass %, relative to the total mass of the positive electrode slurry. When the content of the binder is equal to or greater than the above lower limit, the positive electrode active material 52 is more easily supported on the first porous body 51. When the content of the binder is equal to or less than the above upper limit, the viscosity of the positive electrode slurry can be reduced, and the first porous body 51 is more easily impregnated with the binder.

[0051] The content of the organic solvent in the positive electrode slurry is, for example, preferably 10 to 90 mass %, more preferably 20 to 80 mass %, and even more preferably 30 to 65 mass %, relative to the total mass of the positive electrode slurry. When the content of the organic solvent is equal to or greater than the lower limit, the materials can be easily mixed uniformly. When the content of the organic solvent is equal to or less than the upper limit, the electric capacity can be further increased.

[0052] Next, the positive electrode slurry is impregnated into the first porous body 51 to prepare a positive electrode layer precursor (step S12). By impregnating the first porous body 51 with the positive electrode slurry, the positive electrode slurry penetrates into the pores 51a of the first porous body 51, and the positive electrode active material 52 is supported. In addition, the positive electrode slurry is attached to the surface of the first porous body 51. As a method for impregnating the positive electrode slurry into the first porous body 51, for example, a method of immersing the first porous body 51 in a container containing the positive electrode slurry can be mentioned. The temperature during immersion may be room temperature (for example, 5 to 30°C). The pressure during immersion may be normal pressure (for example, 0.1 MPa). The immersion time (immersion time) is, for example, preferably 10 to 60 seconds, more preferably 20 to 50 seconds. When the immersion time is equal to or greater than the above lower limit, the positive electrode slurry can be sufficiently impregnated into the first porous body 51. When the immersion time is equal to or less than the above upper limit, productivity can be further improved.

[0053] Next, the positive electrode layer precursor is laminated on one surface of the solid electrolyte layer 7 (S13). The positive electrode layer precursor has the positive electrode slurry attached to its surface, and therefore, by laminating the positive electrode layer precursor on one surface of the solid electrolyte layer 7, the adhesion between the positive electrode layer precursor and the solid electrolyte layer 7 can be further improved.

[0054] Next, the laminate of the positive electrode layer precursor and the solid electrolyte layer 7 is fired (S14). By firing the laminate of the positive electrode layer precursor and the solid electrolyte layer 7 together, the organic solvent contained in the positive electrode slurry is removed, and a first laminate in which the positive electrode layer 5 and the solid electrolyte layer 7 are bonded together is obtained. By simultaneously firing the laminate of the positive electrode layer precursor and the solid electrolyte layer 7, it is possible to bond the positive electrode layer 5 and the solid electrolyte layer 7 even if both the positive electrode layer precursor and the solid electrolyte layer 7 are dense materials that cannot be sufficiently bonded even by applying pressure. Therefore, it is possible to easily bond the positive electrode layer 5 and the solid electrolyte layer 7 regardless of the type of the solid electrolyte layer 7, and it is possible to further increase the degree of freedom in material selection in battery design.

[0055] In step S14, the laminate of the positive electrode layer precursor and the solid electrolyte layer 7 is placed in a firing furnace or the like and subjected to a heat treatment. Examples of the firing furnace include a lamp furnace and a muffle furnace. The temperature in the heat treatment (firing temperature) is, for example, preferably 100 to 1500°C, more preferably 200 to 1300°C, and even more preferably 300 to 1100°C. When the firing temperature is equal to or higher than the above lower limit, the organic solvent can be sufficiently removed. When the firing temperature is equal to or lower than the above upper limit, the environmental load can be reduced. In addition to the organic solvent, the binder can also be removed by setting the firing temperature to 300° C. By removing the binder, the contact resistance between the positive electrode active material 52 and the solid electrolyte layer 7 can be further reduced. The firing temperature can be adjusted appropriately depending on the electrical characteristics of the battery 1 and the contact resistance between the positive electrode active material 52 and the solid electrolyte layer 7.

[0056] The electrochemical cell (all-solid-state battery) of this embodiment can be manufactured using the first laminate produced by the above-mentioned steps S11 to S14. An example of a flowchart of the method for manufacturing an electrochemical cell of this embodiment is shown in Figure 4. In Figure 4, steps S11 to S14 are common to the flowchart of Figure 3 described above, and therefore description thereof will be omitted.

[0057] 4, the produced first laminate is bonded to the anode layer 6 (S15). The bonding of the first laminate and the anode layer 6 is preferably performed by applying pressure. At this time, the anode layer 6 is laminated on the other surface of the solid electrolyte layer 7, and pressure is applied in the thickness direction of the solid electrolyte layer 7. By applying pressure, an electrode body 3 is obtained in which the cathode layer 5, solid electrolyte layer 7, and anode layer 6 are laminated in this order.

[0058] When applying pressure, known pressurizing means can be used. Examples of pressurizing means include mechanical pressurization and gas pressurization. Examples of mechanical pressurization include pressurization via a ball screw or hydraulic pressure. Examples of gas pressurization include pressurization via air. The pressure (applied pressure) during bonding is, for example, preferably 100 to 2000 MPa, more preferably 200 to 1500 MPa, and even more preferably 300 to 1000 MPa. When the applied pressure is equal to or greater than the above lower limit, an electrode body 3 in which the layers are sufficiently adhered to each other can be obtained. When the applied pressure is equal to or less than the above upper limit, deterioration of the layers, particularly the positive electrode layer 5, can be suppressed.

[0059] The negative electrode layer 6 is preferably made of a material that can be bonded under pressure to the solid electrolyte layer 7. An example of such a material is metallic lithium.

[0060] The obtained electrode body 3 is placed between the positive electrode can 10 and the negative electrode can 20, and the positive electrode can 10 and the negative electrode can 20 are assembled by crimping and sealing with a gasket 30 interposed therebetween (S16). By step S16, an all-solid-state battery 1 in which the electrode body 3 is housed inside the exterior case 2 is obtained.

[0061] Examples of the gasket 30 include plastic resins such as polypropylene resin (PP), polyphenyl sulfide (PPS), polyethylene terephthalate (PET), polyamide, liquid crystal polymer (LCP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), polyether ether ketone resin (PEEK), polyether nitrile resin (PEN), polyether ketone resin (PEK), polyarylate resin, polybutylene terephthalate resin (PBT), polycyclohexane dimethylene terephthalate resin, polyether sulfone resin (PES), polyamino bismaleimide resin, polyetherimide resin, and fluororesin. Among these, using polypropylene resin for the gasket 30 is preferable from the viewpoint of preventing significant deformation of the gasket during use or storage in a high-temperature environment and further improving the sealing performance of the all-solid-state battery. The plastic resin constituting the gasket 30 may be one type used alone or two or more types used in combination.

[0062] Gasket 30 is sandwiched between positive electrode can 10 and negative electrode can 20, and is at least partially compressed. The compression ratio at this time is not particularly limited, and may be set within a range that can reliably seal the inside of battery 1 and does not cause rupture in gasket 30.

[0063] Next, a second embodiment of the method for producing an electrochemical cell will be described with reference to FIG. This embodiment is characterized in that, in addition to the positive electrode layer precursor of the above-described embodiment, an negative electrode layer precursor is also prepared on the negative electrode side, and a laminate of the positive electrode layer precursor, the solid electrolyte layer 7, and the negative electrode layer precursor is fired to prepare a second laminate in which the positive electrode layer 5, the solid electrolyte layer 7, and the negative electrode layer 6 are joined together. According to the method for manufacturing an electrochemical cell of this embodiment, even if the negative electrode layer 6 is made of a material having the second porous body 61, the adhesion to the solid electrolyte layer 7 can be further improved. This further increases the degree of freedom in material selection in battery design.

[0064] In addition to step S11 and step S12 described above, this embodiment includes the following steps: a step (S21) of preparing an anode slurry; a step (S22) of impregnating a second porous body 61 with the anode slurry to prepare an anode layer precursor; a step (S23) of stacking the cathode layer precursor on one surface of the solid electrolyte layer 7 and the anode layer precursor on the other surface of the solid electrolyte layer 7; a step (S24) of firing the stack of the cathode layer precursor, the solid electrolyte layer 7, and the anode layer precursor; and a step (S25) of placing the obtained second stack (electrode body 3) between the cathode can 10 and the anode can 20, and assembling the cathode can 10 and the anode can 20 by crimping and sealing them with the gasket 30 interposed therebetween.

[0065] In this embodiment, steps S21 and S22 for preparing the negative electrode layer precursor are common to steps S11 and S12 for preparing the positive electrode layer precursor, and therefore, description thereof will be omitted. In step S23, a positive electrode layer precursor is laminated on one surface of the plate-shaped (sheet-shaped or disc-shaped) solid electrolyte layer 7, and a negative electrode layer precursor is laminated on the other surface. The positive electrode layer precursor has a positive electrode slurry attached to the surface of the first porous body 51, and the negative electrode layer precursor has a negative electrode slurry attached to the surface of the second porous body 61, thereby further enhancing adhesion to the solid electrolyte layer 7.

[0066] Next, the laminate of the positive electrode layer precursor, the solid electrolyte layer 7, and the negative electrode layer precursor is fired all at once, thereby obtaining a second laminate in which the positive electrode layer 5, the solid electrolyte layer 7, and the negative electrode layer 6 are joined together (S24). The firing temperature during firing is the same as the firing temperature in step S14 described above.

[0067] The obtained second laminate (electrode body 3) is placed between the positive electrode can 10 and the negative electrode can 20, and the positive electrode can 10 and the negative electrode can 20 are assembled by crimping and sealing them via a gasket 30, thereby producing a battery 1 in which the electrode body 3 is housed inside the outer casing 2 (S25).

[0068] The electrochemical cell manufacturing method of the present invention involves firing a laminate of a cathode layer precursor, which is a first porous body impregnated with a cathode slurry containing a cathode active material, and a solid electrolyte layer to form a first laminate in which the cathode layer and the solid electrolyte layer are bonded together. This allows for easy bonding of the cathode layer and the solid electrolyte layer regardless of the type of solid electrolyte layer. This allows for greater freedom in material selection in battery design. In addition, since the conventional sol-gel method does not require steps such as sol preparation and sol gelation, the time and cost required for manufacturing can be significantly reduced. In the electrochemical cell of the present invention, the positive electrode layer has a first laminate in which a positive electrode active material is supported in the pores of a first porous body and the positive electrode layer and a solid electrolyte layer are joined together, thereby increasing the contact area between the active material and the porous body and reducing the internal resistance of the positive electrode layer. The electrochemical cell of the present invention has a positive electrode layer with reduced internal resistance, allowing the use of various solid electrolyte layers. This allows for greater freedom in material selection in battery design. In addition, unlike the sol-gel method for producing a porous solid electrolyte layer, the cell does not require the steps of sol preparation and sol gelation, significantly reducing the time and cost required for production.

[0069] The electrochemical cell and the method for manufacturing an electrochemical cell according to the present invention have been described above, but the present invention is not limited to the above-described embodiments and can be modified as appropriate within the scope of the invention. For example, in the above-described embodiment, the positive electrode layer precursor is produced by impregnating the positive electrode slurry into the first porous body 51. However, the first laminate may be produced using a positive electrode layer precursor that is prepared in advance. For example, in the above-described embodiment, the negative electrode layer is bonded to the first laminate. However, the positive electrode layer may be bonded to the solid electrolyte layer after bonding the solid electrolyte layer to the negative electrode layer. In the above-described embodiment, there is one electrode body 3, but the number of electrode bodies may be two or more. By using two or more electrode bodies, the electric capacity of the electrochemical cell can be further increased. According to the method for producing an electrochemical cell of the present invention, electrode assemblies can be produced easily and in large quantities, and therefore, an electrochemical cell having two or more electrode assemblies can be easily produced. [Explanation of symbols]

[0070] REFERENCE SIGNS LIST 1... electrochemical cell, 2... exterior body, 3... electrode body, 5... positive electrode layer, 6... negative electrode layer, 7... solid electrolyte layer, 10... positive electrode can, 20... negative electrode can, 30... gasket, 51... first porous body, 51a, 61a... holes, 52... positive electrode active material, 61... second porous body, 62... negative electrode active material

Claims

1. A method for manufacturing an electrochemical cell having a solid electrolyte layer, a positive electrode layer located on one surface of the solid electrolyte layer, and a negative electrode layer located on the other surface of the solid electrolyte layer, wherein a negative electrode active material constituting the negative electrode layer is metallic lithium, a cathode layer precursor obtained by impregnating a first porous body with a cathode slurry containing a cathode active material is laminated on one surface of the solid electrolyte layer, and the laminate is fired to bond the cathode layer to the one surface of the solid electrolyte layer; an anode layer is laminated on the other surface of the solid electrolyte layer; and pressure is applied to the anode layer in a thickness direction of the solid electrolyte layer to bond the anode layer to the solid electrolyte layer.

2. The method for producing an electrochemical cell according to claim 1 , wherein the solid electrolyte layer is not porous.

3. 3. The method for producing an electrochemical cell according to claim 1, wherein the solid electrolyte constituting the solid electrolyte layer contains a garnet-type oxide represented by the following formula (1): Li-La-M'-M"-O...(1) [In formula (1), M′ and M″ represent one or more elements selected from Zr, Nb, Ta, Ga, and Ba.]

4. The method for producing electrochemical cell according to any one of claims 1 to 3, wherein the first porous body comprises one or more selected from the Nasicon oxide represented by the following formula (2) and the Perovskite oxide represented by the following formula (3): Li １＋ｙ Al ｙ Today ２－ｙ (PO ４ ) ３ ・・・(2) Li ３ｘ The ２／３－ｘ TO ３ ・・・(3) [In formula (2), y is a number from 0.05 to 0.

6. In formula (3), x is a number from 0.033 to 0.17.]

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