Method for producing solid state battery

Abstract

A method for producing a solid state battery including the steps of: (a) obtaining an active material slurry; (b) obtaining a solid electrolyte slurry; (c) obtaining a current collector slurry; (d) forming an active material green sheet and a solid electrolyte green sheet; (e) laminating the solid electrolyte green sheet on one surface of the active material green sheet to form a first green sheet group, and forming a current collector green sheet layer on the other surface of the active material green sheet to form a second green sheet group; (f) heating the second green sheet group at not less than 200° C. and not greater than 400° C. in an oxidizing atmosphere; and (g) baking the second green sheet group having heated in the step (f) in a low oxygen atmosphere at a baking temperature higher than the heating temperature in the step (f) to obtain a laminate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a vertical cross section of a solid electrolyte green sheet formed on a carrier film.

FIG. 2 is a schematic diagram showing a vertical cross section of an active material green sheet formed on a carrier film.

FIG. 3 is a schematic diagram showing a vertical cross section of a solid electrolyte green sheet and a carrier film attached onto a substrate having a polyester film.

FIG. 4 is a schematic diagram showing how the carrier film is peeled off from the solid electrolyte green sheet attached onto the substrate.

FIG. 5 is a schematic diagram showing a vertical cross section of 20 solid electrolyte green sheets and one active material green sheet attached onto a substrate having a polyester film.

FIG. 6 is a schematic diagram showing a vertical cross section of a second green sheet group sandwiched between ceramic plates.

FIG. 7 is a schematic diagram showing a vertical cross section of a coin type battery produced in EXAMPLEs of the present invention.

FIG. 8 shows X-ray diffraction patterns of a second green sheet group produced in EXAMPLE 1 before and after the heat treatment in the fourth step.

Claims

1. A method for producing a solid state battery comprising a laminate including a solid electrolyte layer, an active material layer and a current collector layer, said method comprising the steps of: (a) dispersing an active material powder in a solvent containing a binder and a plasticizer to obtain an active material slurry;(b) dispersing a solid electrolyte powder in a solvent containing a binder and a plasticizer to obtain a solid electrolyte slurry;(c) dispersing a current collector powder in a solvent containing a binder and a plasticizer to obtain a current collector slurry;(d) forming an active material green sheet and a solid electrolyte green sheet using said active material slurry and said solid electrolyte slurry, respectively;(e) laminating said solid electrolyte green sheet on one surface of said active material green sheet to form a first green sheet group, and forming a current collector green sheet layer on the other surface of said active material green sheet using said current collector slurry to form a second green sheet group;(f) heating said second green sheet group at not less than 200° C. and not greater than 400° C. in an oxidizing atmosphere; and(g) baking said second green sheet group having heated in said step (f) in a low oxygen atmosphere at a baking temperature higher than the heating temperature in said step (f) to obtain a laminate including a solid electrolyte layer, an active material layer and a current collector layer.

2. The method for producing a solid state battery in accordance with claim 1, wherein said baking temperature in said step (g) is not less than 700° C. and not greater than 1000° C.

3. The method for producing a solid state battery in accordance with claim 1, wherein said current collector powder comprises at least one selected from the group consisting of copper, nickel, palladium, gold and platinum.

4. The method for producing a solid state battery in accordance with claim 1, wherein in said step (g), an oxygen equilibrium partial pressure (atm) of said low oxygen atmosphere represented by P1 and said baking temperature (° C.) represented by T satisfies −0.0310 T+33.5−log P1−0.0300 T+38.1.

5. The method for producing a solid state battery in accordance with claim 1, wherein in said step (f), said oxidizing atmosphere contains an oxygen gas, andsaid oxidizing atmosphere has an oxygen gas equilibrium partial pressure (P2) of not less than 0.1 atm and not greater than 1.0 atm.

6. The method for producing a solid state battery in accordance with claim 1, wherein said step (e) further comprises cutting said first green sheet group or said second green sheet group into a specified size.

7. The method for producing a solid state battery in accordance with claim 1, wherein said method further comprises, after said step (g), forming an external electrode connected to said current collector layer on one surface of said laminate.

8. The method for producing a solid state battery in accordance with claim 1, wherein said active material powder comprises a first phosphoric acid compound capable of absorbing and releasing lithium ions, andsaid solid electrolyte powder comprises a second phosphoric acid compound having lithium ion conductivity.

9. The method for producing a solid state battery in accordance with claim 8, wherein said first phosphoric acid compound is represented by the following formula (1): LiMPO4  (1)where M represents at least one selected from the group consisting of Mn, Fe, Co and Ni.

10. The method for producing a solid state battery in accordance with claim 8, wherein said second phosphoric acid compound is represented by the following formula (2): Li1+XMIIIXTiIV2−X(PO4)  (2)where MIII represents at least one selected from the group consisting of Al, Y, Ga, In and La, and 0X0.6.