Method for producing sulfide solid-state battery, and sulfide solid-state battery

1. A method for producing a sulfide solid-state battery that includes a cathode, an anode, and a solid electrolyte layer provided between the cathode and the anode, the method comprising:

layering an anode mixture (a) over a surface of an anode current collector, to form an anode mixture layer A 1 , the anode mixture (a) containing a polyamic acid, and silicon-based active material but not containing a sulfide solid electrolyte;

heating the anode mixture layer A 1 to imidize the polyamic acid, to make an anode mixture layer A 2 which contains a polyimide and in which a void is present;

layering a sulfide solid electrolyte over a surface of the anode mixture layer A 2 on an opposite side of the anode current collector;

pressing the anode mixture layer A 2 , over which the sulfide solid electrolyte is layered, to insert the sulfide solid electrolyte into the void in the anode mixture layer A 2 , to make an anode mixture layer A 3 that contains the sulfide solid electrolyte; and

layering an anode mixture (b) over a surface of the anode mixture layer A 3 , to form an anode mixture layer B, the anode mixture (b) containing carbonaceous active material and binder.

2. The method according to claim 1 , wherein the anode mixture layer A 3 is no more than 3 μm in thickness.

3. The method according to claim 1 , wherein the anode current collector contains copper.

4. The method according to claim 1 , wherein

a relation of 10≤β−α is satisfied when a volume ratio of an anode active material in the anode mixture layer A 3 is α (%), and a volume ratio of an anode active material in the anode mixture layer B is β (%).

5. The method according to claim 1 , wherein the volume ratio of the anode active material in the anode mixture layer A 3 is no more than 60%.

6. The method according to claim 1 , wherein the binder contained in the anode mixture layer B is different from a binder contained in the anode mixture layer A 3 .

7. The method according to claim 6 , wherein the binder contained in the anode mixture layer B is styrene-butadiene rubber.

8. A sulfide solid-state battery that includes a cathode, an anode, and a solid electrolyte layer provided between the cathode and the anode, wherein

the anode comprises:

an anode current collector;

an anode mixture layer A that is provided over a surface of the anode current collector; and

an anode mixture layer B that is provided over a surface of the anode mixture layer A on an opposite side of the anode current collector,

the anode mixture layer A comprises:

silicon-based active material;

a polyimide; and

a sulfide solid electrolyte,

the anode mixture layer B comprises:

carbonaceous active material; and

binder, and

the anode mixture layer A is no more than 3 μm in thickness.

9. The sulfide solid-state battery according to claim 8 , wherein the anode current collector contains copper.

10. The sulfide solid-state battery according to claim 8 , wherein

a relation of 10≤β−α is satisfied when a volume ratio of an anode active material in the anode mixture layer A is α (%), and a volume ratio of an anode active material in the anode mixture layer B is β (%).

11. The sulfide solid-state battery according to claim 8 , wherein the volume ratio of the anode active material in the anode mixture layer A is no more than 60%.

12. The sulfide solid-state battery according to claim 8 , wherein

a binder contained in the anode mixture layer A is different from the binder contained in the anode mixture layer B.

13. The sulfide solid-state battery according to claim 12 , wherein the binder contained in the anode mixture layer B is styrene-butadiene rubber.