Method for manufacturing electrochemical cells

Abstract

To provide a manufacturing method of an electrochemical cell and an electrochemical cell, capable of increasing manufacturing efficiency.SOLUTION: There is provided a manufacturing method of an electrochemical cell, the electrochemical cell including a solid electrolyte layer 10, a positive electrode layer 20 located on one side 10A of the solid electrolyte layer 10, and a negative electrode layer 30 located on the other side 10B of the solid electrolyte layer 10. The manufacturing method includes a step in which an impregnated sheet comprising a conductive sheet 22 impregnated with positive electrode slurry that contains a positive electrode material and a binder is located on the one side 10A of the solid electrolyte layer 10, and then the positive electrode slurry in the impregnated sheet is solidified to form the positive electrode layer 20.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] One known method for forming a positive electrode layer on the solid electrolyte layer of an all-solid-state battery is a screen printing method, in which a positive electrode slurry is prepared and applied to the surface of the solid electrolyte layer. For example, Patent Document 1 proposes a method for manufacturing an electrode plate in which resin particles consisting of active material particles and a binder resin are deposited on the main surface of an electrode substrate by a screen printing method to form an active material layer (positive electrode layer). According to the invention of Patent Document 1, efforts are made to improve the binding force between active material particles in the active material layer. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2010 / 067440 [Overview of the project] [Problems that the invention aims to solve]

[0004] In screen printing, a mesh is used to mask the positive electrode slurry. When forming a positive electrode layer on a solid electrolyte layer using screen printing, the positive electrode slurry adheres to the mesh during printing, resulting in slurry loss. In addition, with screen printing, the position and shape of the printing press must be designed according to the shape and thickness of the solid electrolyte layer, making the manufacturing of all-solid-state batteries time-consuming (low manufacturing efficiency).

[0005] Therefore, the present invention aims to provide a method for manufacturing an electrochemical cell and an electrochemical cell that can improve manufacturing efficiency. [Means for solving the problem]

[0006] 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 side of the solid electrolyte layer, and a negative electrode layer located on the other side of the solid electrolyte layer, comprising the steps of: placing an impregnated sheet, which is a conductive sheet impregnated with a positive electrode slurry containing a positive electrode active material and a binder, on one side of the solid electrolyte layer; and then solidifying the positive electrode slurry in the impregnated sheet to form the positive electrode layer.

[0007] This configuration reduces the loss of the positive electrode slurry. In addition, the shape of the conductive sheet can be changed according to the shape and thickness of the solid electrolyte layer. Therefore, there is no need to design the position and shape of the printing press used in screen printing, which can improve manufacturing efficiency.

[0008] Furthermore, the amount of positive electrode slurry impregnating the impregnated sheet may be 30 to 95 parts by mass per 100 parts by mass of the conductive sheet. This configuration allows for easy adjustment of the shape and thickness of the positive electrode layer, thereby increasing manufacturing efficiency.

[0009] Alternatively, the laminate of the impregnated sheet and the solid electrolyte layer may be sintered to solidify the positive electrode slurry in the impregnated sheet, thereby forming the positive electrode layer. This configuration allows for easier formation of the positive electrode layer and improves manufacturing efficiency.

[0010] The electrochemical cell according to the present invention includes an electrode body having a solid electrolyte layer, a positive electrode layer located on one side of the solid electrolyte layer, and a negative electrode layer located on the other side of the solid electrolyte layer, wherein the positive electrode layer includes a conductive sheet.

[0011] This configuration reduces the loss of the positive electrode slurry. In addition, the shape of the conductive sheet can be changed according to the shape and thickness of the solid electrolyte layer. Therefore, there is no need to design the position and shape of the printing press used in screen printing, which can improve manufacturing efficiency. In addition, since the positive electrode layer includes a conductive sheet, the conductivity of the positive electrode layer can be further increased.

[0012] Also, two or more of the electrode bodies may be stacked. According to this configuration, in addition to the manufacturing efficiency, the output of the battery can be further increased.

Advantages of the Invention

[0013] According to the method for manufacturing an electrochemical cell and the electrochemical cell of the present invention, the manufacturing efficiency can be increased.

Brief Description of the Drawings

[0014] [Figure 1] FIG. 1 is a perspective view showing the appearance of an electrochemical cell according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing an example of a solid electrolyte layer housed in the electrochemical cell. [Figure 3] FIG. 3 is a plan view showing a state in which a positive electrode layer is provided on the solid electrolyte layer shown in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV shown in FIG. 3. [Figure 5] FIG. 5 is a perspective view showing a method for manufacturing two or more electrode bodies.

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the electrochemical cell according to the present invention will be described with reference to the drawings. In the following embodiments, as an example of the electrochemical cell, a coin-type all-solid-state battery (hereinafter, also simply referred to as "battery") will be cited, and the configuration of this battery will be described. In the drawings used in the following description, the scale of each member is appropriately changed and displayed in order to make each member recognizable.

[0016] ≪Electrochemical Cell≫ As shown in FIG. 1, the battery (electrochemical cell) 1 of the present embodiment is a button-type battery having a circular shape in plan view. This battery 1 includes a container-shaped exterior body 2 and an electrode body housed inside the exterior body 2.

[0017] The outer package 2 is formed of a laminate film. The laminate film has a metal foil, a fusion layer provided on the inner surface and covering the metal foil, and a protective layer provided on the outer surface and covering the metal foil. The metal foil is formed of a metal that blocks outside air and water vapor, such as aluminum or stainless steel. The fusion layer is formed of, for example, polyolefin such as polyethylene or polypropylene, or a copolymer containing two or more kinds of resins. The protective layer is formed of, for example, the above-mentioned polyolefin, polyester such as polyethylene terephthalate, or polyamide such as nylon.

[0018] The electrode body has 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. As shown in FIG. 4, the electrode body 3 of the present embodiment has a solid electrolyte layer 10, a positive electrode layer 20 located on one surface 10A of the solid electrolyte layer 10, and a negative electrode layer 30 located on the other surface 10B of the solid electrolyte layer 10, and the positive electrode layer 20 includes a conductive sheet 22.

[0019] <Solid electrolyte layer> The solid electrolyte layer 10 contains a solid electrolyte. As the solid electrolyte, known ones used in all-solid-state batteries can be used. Examples of the solid electrolyte include oxide-based solid electrolytes. Examples of the oxide-based solid electrolyte include, for example, Li 1.5 Al 0.5 Ge 1.5 P3O 12 (LAGP), Li7La3Zr2O 12 (LLZ), Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP), Li 10 GeP2S 12 (LGPS), Li 3.5 Ge 0.5 V 0.5O4 (LGVO), LiTa2PO8 (LTPO), La 0.57 Li 0.29 TiO3 (LLTO), Li6BaLa2Ta2O 12 (LBLTO), Li 3.5 Si 0.5 P 0.5 O4 (LSPO), Li 6.25 La3Zr2Al 0.25 O 12 and the like can be mentioned. These solid electrolytes may be used alone or in combination of two or more.

[0020] The thickness of the solid electrolyte layer 10 is preferably, for example, 10 to 10000 μm, more preferably 10 to 5000 μm, and even more preferably 10 to 1000 μm. When the thickness of the solid electrolyte layer 10 is at least the above lower limit value, the capacitance can be further increased. When the thickness of the solid electrolyte layer 10 is at most the above upper limit value, the internal resistance can be further reduced. The thickness of the solid electrolyte layer 10 can be determined, for example, by observing a cross section obtained by cutting the electrode body 3 in the thickness direction with a microscope or the like.

[0021] <Positive electrode layer> The positive electrode layer 20 includes a positive electrode active material and a conductive sheet 22. As the positive electrode active material, known ones used in all-solid-state batteries can be utilized. Examples of the positive electrode active material 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 (M represents a metal element such as Co, Ni, Mn, Al, Fe, etc.). Examples of the two-component positive electrode material include, for example, Li 1-x CoMnO4 (x is a number satisfying 0 < x < 1), Li x FePO4 (x is a number satisfying 0 < x ≤ 1), Li x V6O 13 (x is a number satisfying 0 < x ≤ 1), Li 1-x Mn2O4 (x is a number satisfying 0 < x < 1), Li 1-x Ni 0.5 Mn 1.5 O4 (x is a number satisfying 0 < x < 1), etc. can be mentioned. Examples of ternary cathode materials include LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 Examples include O2. These positive electrode active materials may be used individually or in combination of two or more types.

[0022] The conductive sheet 22 can be any sheet that has both or either ionic conductivity and / or electronic conductivity, and can be impregnated with positive electrode slurry. Examples of conductive sheets 22 include carbon sheets and carbon nanotube sheets. A carbon sheet is preferred as the conductive sheet 22 because its shape can be easily adjusted and the conductivity of the positive electrode layer 20 can be further increased.

[0023] The thickness of the conductive sheet 22 is preferably, for example, 1 to 1000 μm, more preferably 1 to 100 μm, and even more preferably 1 to 10 μm. If the thickness of the conductive sheet 22 is greater than or equal to the lower limit, the amount of impregnation described later can be increased. If the thickness of the conductive sheet 22 is less than or equal to the upper limit, the internal resistance can be further reduced. The thickness of the conductive sheet 22 can be determined, for example, by observing a cross-section of the electrode body 3 cut in the thickness direction using a microscope or the like.

[0024] The thickness of the positive electrode layer 20 is preferably, for example, 10 to 1000 μm, more preferably 10 to 200 μm, and even more preferably 10 to 30 μm. If the thickness of the positive electrode layer 20 is above the lower limit, the capacitance can be increased. If the thickness of the positive electrode layer 20 is below the upper limit, the internal resistance can be reduced. The thickness of the positive electrode layer 20 can be determined, for example, by observing a cross-section of the electrode body 3 cut in the thickness direction using a microscope or the like.

[0025] <Negative electrode layer> The negative electrode layer 30 contains a negative electrode active material. A known negative electrode active material used in all-solid-state batteries can be used. Examples of negative electrode active materials include metallic lithium, Li4Ti5O12 (LTO), graphite, Li 15 Examples include Si-based compounds such as Si4. The negative electrode active material may be used alone or in combination of two or more types.

[0026] The thickness of the negative electrode layer 30 is preferably, for example, 1 to 500 μm, more preferably 1 to 200 μm, and even more preferably 1 to 10 μm. If the thickness of the negative electrode layer 30 is greater than or equal to the lower limit, the capacitance can be increased. If the thickness of the negative electrode layer 30 is less than or equal to the upper limit, the internal resistance can be reduced. The thickness of the negative electrode layer 30 can be determined, for example, by observing a cross-section of the electrode body 3 cut in the thickness direction using a microscope or the like.

[0027] ≪Method for manufacturing electrochemical cells≫ The present invention provides a method for manufacturing an electrochemical cell, comprising the steps of: positioning an impregnated sheet, which is a conductive sheet impregnated with a positive electrode slurry containing a positive electrode active material and a binder, on one side of the solid electrolyte layer; and then solidifying the positive electrode slurry in the impregnated sheet to form the positive electrode layer. The method for manufacturing the electrochemical cell of this embodiment will be described in detail below with reference to the drawings.

[0028] As shown in Figure 2, a solid electrolyte layer 10 with a circular shape in plan view is prepared. To manufacture the solid electrolyte layer 10, an electrolyte slurry is prepared by mixing a solid electrolyte, a binder, and, if necessary, a solvent, dispersant, plasticizer, etc. This electrolyte slurry is coated onto the surface of a carrier film to the required thickness using a sheet molding method or the like. The coated material is then peeled off the carrier film and fired in an electric furnace or the like to obtain the solid electrolyte layer 10.

[0029] Examples of solid electrolytes used in electrolyte slurry include the solid electrolyte contained in the solid electrolyte layer 10 described above. Examples of binders used in electrolyte slurries include polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), acrylic resin, polyimide, and inorganic binders such as silicate-based inorganic binders or phosphate-based inorganic binders. Solvents used in electrolyte slurries include alcohols, ketones, esters, and water. 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. Examples of esters include methyl acetate, ethyl acetate, n-propyl acetate, and isopropyl acetate. Examples of dispersants used in electrolyte slurries include various compounds such as polycarboxylic acid-based, polyether-based, alkyl sulfonic acid-based, and alkyl polyamine-based compounds. Examples of plasticizers used in electrolyte slurries include diisononyl adipate, dioctyl phthalate, and diisononyl phthalate.

[0030] The solid electrolyte content in the electrolyte slurry is preferably, for example, 40 to 80% by mass, more preferably 50 to 80% by mass, and even more preferably 60 to 80% by mass, relative to the total mass of the electrolyte slurry. If the solid electrolyte content is above the lower limit, the internal resistance can be further reduced. If the solid electrolyte content is below the upper limit, the viscosity of the electrolyte slurry can be reduced, and handling properties can be further improved.

[0031] The binder content in the electrolyte slurry is preferably, for example, 1 to 50% by mass, more preferably 1 to 40% by mass, and even more preferably 1 to 30% by mass, relative to the total mass of the electrolyte slurry. If the binder content is above the lower limit, the strength of the solid electrolyte layer 10 can be further increased. If the binder content is below the upper limit, the internal resistance can be further reduced.

[0032] By coating the prepared electrolyte slurry to the thickness of the solid electrolyte layer 10 described above, the capacitance of the solid electrolyte layer 10 can be further increased, and the internal resistance of the solid electrolyte layer 10 can be further reduced.

[0033] Examples of carrier films include polyolefins, polyesters, and polyamides.

[0034] The firing atmosphere should preferably contain oxygen to minimize oxygen deficiency, and a dry atmosphere is even more preferable if moisture is a concern. To prevent distortion of the solid electrolyte sheet during firing, it is preferable to sandwich it between ceramic plates (made of Al2O3, MgO, etc.) or graphite plates. To prevent reactions with the ceramic plates and to suppress the volatilization of Li, a sheet made of the same material as the solid electrolyte or an oxide containing Li may be inserted between the ceramic plates.

[0035] The firing temperature is preferably, for example, 100 to 1500°C, more preferably 300 to 1350°C, and even more preferably 500 to 1200°C. If the firing temperature is above the lower limit, the strength of the solid electrolyte layer 10 can be further increased. If the firing temperature is below the upper limit, the energy required for firing can be reduced.

[0036] The firing time is preferably 15 to 30 hours, more preferably 18 to 27 hours, and even more preferably 20 to 24 hours. If the firing time is above the lower limit, the strength of the solid electrolyte layer 10 can be further increased. If the firing time is below the upper limit, the productivity of the solid electrolyte layer 10 can be further increased. In addition to the method of coating the carrier film with an electrolyte slurry and then firing it as described above, the solid electrolyte layer 10 may also be manufactured by press-molding a mixture of powdered solid electrolyte and binder, and then firing it under the conditions described above. In this case, the solid electrolyte layer 10 can be made into various shapes, such as a sheet, a plate, or a pellet.

[0037] Next, a negative electrode layer 30 is formed on the other surface 10B of the obtained solid electrolyte layer 10. For forming the negative electrode layer 30, methods such as hot pressing for thermocompression bonding or sputtering for film deposition can be used. By using the thermocompression bonding method or by forming a metal (In, Cu, Al, Au, etc.) film on the solid electrolyte layer 10 using a film deposition method, and then alloying it with lithium, the negative electrode layer 30 can be formed on the other surface 10B of the solid electrolyte layer 10. The formation of the negative electrode layer 30 may be carried out after the solidification process described later.

[0038] Next, a positive electrode slurry containing the positive electrode active material and binder is prepared (preparation step). In the preparation process, the positive electrode slurry is prepared by mixing the positive electrode active material, the binder, and, if necessary, a solvent, dispersant, plasticizer, etc. Examples of positive electrode active materials used in positive electrode slurry include the positive electrode active material contained in the positive electrode layer 20. Examples of binders used in positive electrode slurries include resins similar to those used in electrolyte slurries. The solvent used in the positive electrode slurry can be the same solvent used in the electrolyte slurry. Dispersants used in positive electrode slurries include those similar to those used in electrolyte slurries. Plasticizers used in positive electrode slurries include dispersants similar to those used in electrolyte slurries.

[0039] The content of the positive electrode active material in the positive electrode slurry is preferably, for example, 10 to 90% by mass, more preferably 15 to 60% by mass, and even more preferably 20 to 30% by mass, relative to the total mass of the positive electrode slurry. If the content of the positive electrode active material is above the lower limit, the electrical capacity can be further increased. If the content of the positive electrode active material is below the upper limit, the viscosity of the positive electrode slurry can be reduced, and the handling properties can be further improved.

[0040] The binder content in the positive electrode slurry is preferably, for example, 5 to 80% by mass, more preferably 12 to 65% by mass, and even more preferably 25 to 45% by mass, relative to the total mass of the positive electrode slurry. If the binder content is above the lower limit, the bonding between the solid electrolyte layer 10 and the positive electrode slurry can be further improved. If the binder content is below the upper limit, the electrical properties of the positive electrode layer 20 can be further improved.

[0041] The positive electrode slurry may contain a solid electrolyte. Examples of solid electrolytes include the oxide-based solid electrolytes mentioned above. When the positive electrode slurry contains a solid electrolyte, the solid electrolyte content is preferably, for example, 10 to 90% by mass, more preferably 15 to 60% by mass, and even more preferably 20 to 30% by mass, relative to the total mass of the positive electrode slurry. If the solid electrolyte content is above the lower limit, the internal resistance can be further reduced. If the solid electrolyte content is below the upper limit, the viscosity of the positive electrode slurry can be reduced, and handling properties can be further improved.

[0042] The viscosity of the positive electrode slurry at 25°C is preferably, for example, 1,000 to 10,000 mPa·s, more preferably 3,000 to 9,000 mPa·s, and even more preferably 4,000 to 8,000 mPa·s. If the viscosity of the positive electrode slurry at 25°C is above the lower limit, the positive electrode slurry can be solidified more easily. If the viscosity of the positive electrode slurry at 25°C is below the upper limit, the mass (impregnation amount) of positive electrode slurry impregnated into the conductive sheet 22 can be increased. The viscosity of the positive electrode slurry at 25°C can be determined, for example, by adjusting the temperature of the sample to 25°C, using a B-type viscometer, and reading the value 60 seconds after the rotor starts rotating at a rotation speed of 2000 rpm.

[0043] Next, the conductive sheet 22 is impregnated with the positive electrode slurry to obtain an impregnated sheet (impregnation step). The mass of the positive electrode slurry impregnated into the conductive sheet 22 (the amount of impregnation of the impregnated sheet) is preferably, for example, 30 to 95 parts by mass, more preferably 50 to 95 parts by mass, and even more preferably 65 to 95 parts by mass, per 100 parts by mass of the conductive sheet. If the amount of impregnation of the impregnated sheet is above the lower limit, the electrical properties of the positive electrode layer 20 can be further improved. If the amount of impregnation of the impregnated sheet is below the upper limit, the mass of the impregnated sheet can be reduced, and handling can be further improved. The amount of impregnation of the impregnation sheet can be adjusted by the type of conductive sheet 22, the thickness of the conductive sheet 22, the type of positive electrode slurry, the viscosity of the positive electrode slurry, the impregnation temperature described later, the impregnation time described later, and combinations thereof.

[0044] The temperature at which the conductive sheet 22 is impregnated with the positive electrode slurry (impregnation temperature) is preferably 25 to 200°C, more preferably 50 to 150°C, and even more preferably 70 to 100°C. If the impregnation temperature is above the lower limit, the amount of impregnation can be increased. If the impregnation temperature is below the upper limit, deterioration of the conductive sheet 22 can be suppressed.

[0045] The time for impregnating the conductive sheet 22 with the positive electrode slurry (impregnation time) is preferably 10 seconds or more, more preferably 1 minute or more, and even more preferably 5 minutes or more. If the impregnation time is above the lower limit, the amount of impregnation can be increased. Also, the impregnation time is preferably 1 hour or less, more preferably 30 minutes or less, and even more preferably 10 minutes or less. If the impregnation time is below the upper limit, the productivity of the positive electrode layer 20 can be increased.

[0046] Next, the impregnated sheet is positioned on one side 10A of the solid electrolyte layer 10, and the positive electrode slurry in the impregnated sheet is solidified to form the positive electrode layer 20 (solidification step). The manufacturing method of the electrochemical cell in this embodiment includes a solidification step, which allows the binder contained in the positive electrode slurry to bond the solid electrolyte layer 10 and the conductive sheet 22, thereby forming the positive electrode layer 20 located on one side 10A of the solid electrolyte layer 10. Methods for solidifying the positive electrode slurry in the impregnated sheet include, for example, sintering a laminate of the impregnated sheet and the solid electrolyte layer 10 (sintering method), compressing a laminate of the impregnated sheet and the solid electrolyte layer 10 (compression method), and bonding the impregnated sheet and the solid electrolyte layer 10 using an adhesive and then drying them (adhesion method). As a method for solidifying the positive electrode slurry in the impregnated sheet, a sintering method is preferred because it offers high manufacturing efficiency, improves the bonding between the solid electrolyte layer 10 and the positive electrode slurry, and reduces contact resistance.

[0047] In the sintering method, the sintering temperature is preferably 100 to 1500°C, more preferably 300 to 1350°C, and even more preferably 500 to 1200°C. If the sintering temperature is above the lower limit, the contact resistance can be further reduced. If the sintering temperature is below the upper limit, the deterioration of the conductive sheet 22 can be suppressed.

[0048] The sintering time is preferably 1 to 30 hours, more preferably 10 to 27 hours, and even more preferably 20 to 24 hours. If the sintering time is above the lower limit, the contact resistance can be further reduced. If the sintering time is below the upper limit, the productivity of the electrode body 3 can be further increased. The atmosphere during sintering should preferably be an inert gas atmosphere such as nitrogen or argon, or a vacuum, in order to suppress the effects on the carbon constituting the conductive sheet 22, specifically effects such as oxidation and combustion.

[0049] In the crimping method, the pressure applied during crimping (crimping pressure) is preferably, for example, 10 to 5000 MPa, more preferably 50 to 1000 MPa, and even more preferably 100 to 600 MPa. If the crimping pressure is above the lower limit, contact resistance can be further reduced. If the crimping pressure is below the upper limit, the collapse of the solid electrolyte layer 10 can be suppressed.

[0050] The time required for crimping (crimping time) is preferably 0.5 to 20 hours, more preferably 1 to 10 hours, and even more preferably 1 to 7 hours. If the crimping time is above the lower limit, the contact resistance can be further reduced. If the crimping time is below the upper limit, the productivity of the electrode body 3 can be further increased.

[0051] In the bonding method, conventionally known adhesives can be used as the adhesive. Examples of adhesives include epoxy adhesives, acrylic adhesives, and urethane adhesives. Furthermore, as an adhesive, one may use an adhesive that has been enhanced in conductivity by adding conductive substances such as metal powder.

[0052] The drying temperature is preferably 120 to 500°C, more preferably 160 to 400°C, and even more preferably 200 to 300°C. If the drying temperature is above the lower limit, the solidification of the positive electrode slurry can be further promoted. If the drying temperature is below the upper limit, the bonding between the impregnated sheet and the solid electrolyte layer 10 can be further improved.

[0053] The drying time is preferably 2 to 24 hours, more preferably 2 to 15 hours, and even more preferably 2 to 6 hours. If the drying time is above the lower limit, the positive electrode slurry can be sufficiently solidified. If the drying time is below the upper limit, the productivity of the electrode body 3 can be further increased.

[0054] In the method for solidifying the positive electrode slurry in the impregnated sheet, the sintering method and the compression method may be used individually or in combination. By using both methods in combination, the manufacturing efficiency of the electrode body 3 can be further increased.

[0055] Through the solidification process, an electrode body 3 is obtained in which the positive electrode layer 20 is located on one surface 10A of the solid electrolyte layer 10, as shown in Figures 3 and 4.

[0056] An electrochemical cell may have two or more electrodes. By having two or more electrodes, the electrical capacity of the all-solid-state battery can be further increased.

[0057] The electrode body can be obtained, for example, by sequentially stacking an intermediate 4A in which a positive electrode layer 20 is located on one side of a solid electrolyte layer 10, and an intermediate 4B in which a negative electrode layer 30 is located on one side of a solid electrolyte layer 10, as shown in Figure 5. By sequentially stacking intermediate 4A and intermediate 4B, and then sintering, pressing, etc., an electrode body is obtained in which two or more intermediates 4A and intermediate 4B are stacked. Here, the positive electrode layer 20 includes a conductive sheet 22. The sintering and crimping of the intermediates may be performed one intermediate at a time, or all intermediates may be sintered and crimped together at once. To further improve the manufacturing efficiency of electrochemical cells, it is preferable to perform the sintering and crimping of all intermediates at once. Furthermore, as shown in Figure 5, for example, a negative electrode layer 30 may be formed on the other side of the solid electrolyte layer 10 of the bottommost intermediate 4A using a thermocompression bonding method or a film deposition method. This makes it possible to place a positive electrode layer 20 on one side of the electrode body and a negative electrode layer 30 on the other side.

[0058] The electrochemical cell of the present invention includes a conductive sheet in the positive electrode layer, thereby increasing the conductivity of the positive electrode layer. The electrochemical cell manufacturing method of the present invention uses an impregnated sheet, which is formed by impregnating a conductive sheet with a positive electrode slurry, as the positive electrode layer, thereby reducing the loss of the positive electrode slurry. The electrochemical cell manufacturing method of the present invention allows the shape of the conductive sheet to be changed according to the shape and thickness of the solid electrolyte layer. Therefore, it is not necessary to design the position and shape of the printing press used in the screen printing method, and manufacturing efficiency can be increased. The electrochemical cell manufacturing method of the present invention allows for the simple formation of a positive electrode layer on a solid electrolyte layer. Furthermore, the shape and thickness of the positive electrode layer can be easily adjusted. This improves the workability when manufacturing all-solid-state batteries. The method for manufacturing electrochemical cells according to the present invention does not require a conventional screen printing machine. Since screen printing machines are expensive, the method for manufacturing electrochemical cells according to the present invention is also superior in terms of cost.

[0059] Although the electrochemical cell and method for manufacturing the electrochemical cell of the present invention have been described above, the present invention is not limited to the embodiments described above and can be modified as appropriate without departing from the spirit of the invention. For example, the shape of the solid electrolyte layer may not be circular in plan view, but rather polygonal in plan view. For example, two or more conductive sheets may be used in the positive electrode layer, rather than just one. For example, a conductive sheet may be divided into two or more sections in a direction perpendicular to its thickness (in the planar direction). [Explanation of Symbols]

[0060] 1...Electrochemical cell, 2...Outer casing, 3...Electrode body, 4A, 4B...Intermediate, 10...Solid electrolyte layer, 20...Positive electrode layer, 22...Conductive sheet, 30...Negative electrode layer

Claims

[Claim 1] A method for manufacturing an electrochemical cell having a solid electrolyte layer, a positive electrode layer located on one side of the solid electrolyte layer, and a negative electrode layer located on the other side of the solid electrolyte layer, The process includes the steps of: impregnating a conductive sheet with a positive electrode slurry containing a positive electrode active material, a binder, and a solid electrolyte; positioning the impregnated sheet on one side of the solid electrolyte layer; then sintering the laminate of the impregnated sheet and the solid electrolyte layer to solidify the positive electrode slurry in the impregnated sheet and form the positive electrode layer; The temperature at which the laminate is sintered is 500 to 1200°C. The amount of the positive electrode slurry impregnating the impregnated sheet is 30 to 95 parts by mass per 100 parts by mass of the conductive sheet. The content of the positive electrode active material in the positive electrode slurry is 10 to 90% by mass relative to the total mass of the positive electrode slurry. The content of the solid electrolyte in the positive electrode slurry is 10 to 90% by mass relative to the total mass of the positive electrode slurry. A method for manufacturing an electrochemical cell, wherein the viscosity of the positive electrode slurry at 25°C is 1,000 to 10,000 mPa·s.

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