Solid-state positive electrode, method of manufacture thereof, and battery including the electrode

1. A positive electrode for a solid-state lithium battery, the positive electrode comprising:

a positive active material comprising a lithium transition metal oxide comprising nickel, cobalt, and manganese; and

a first solid electrolyte comprising a sulfide solid electrolyte, wherein a ratio λ of an average particle diameter of the positive active material to an average particle diameter of the first solid electrolyte is

5.5≤λ≤40,

wherein the positive active material has an average particle diameter of 1 μm to 30 μm,

wherein the first solid electrolyte has an average particle diameter of 0.1 μm to 4 μm, and

wherein a content of the positive active material is 60 weight percent to 90 weight percent, based on a total weight of the positive electrode.

2. The positive electrode of claim 1 , wherein a porosity of the positive electrode is less than 25 percent, based on a total volume of the positive electrode.

3. The positive electrode of claim 2 , wherein a content of the positive active material is 30 volume percent to 80 volume percent, based on a total volume of the positive electrode.

4. The positive electrode of claim 2 , wherein a content of the first solid electrolyte is 10 weight percent to 40 weight percent, based on a total weight of the positive electrode.

5. The positive electrode of claim 2 , wherein a particle diameter distribution of the positive electrode active material and a particle diameter distribution of the first solid electrolyte is a bimodal distribution.

6. The positive electrode of claim 1 , wherein the positive electrode active material provides 110 milliampere-hours per gram to 150 milliampere-hours per gram, when discharged at 0.05 milliamperes per square centimeter of the positive electrode at 25° C.

7. A positive electrode assembly for a solid-state lithium battery, the assembly comprising:

the positive electrode of claim 1 ; and

a second solid electrolyte on the positive electrode, wherein the first solid electrolyte and the second solid electrolyte are the same or different.

8. A solid-state lithium battery comprising:

a positive electrode comprising a positive active material comprising a lithium transition metal oxide comprising nickel, cobalt, and manganese, and a first solid electrolyte comprising a sulfide solid electrolyte;

a negative electrode; and

a second solid electrolyte between the positive electrode and the negative electrode,

wherein the first solid electrolyte and the second solid electrolyte are the same or different,

wherein a ratio λ of an average particle diameter of the positive active material to an average particle diameter of the first solid electrolyte is

5.5≤λ≤40,

wherein the positive active material has an average particle diameter of 1 μm to 30 μm,

wherein the first solid electrolyte has an average particle diameter of 0.1 μm to 4 μm, and

wherein a content of the positive active material is 60 weight percent to 90 weight percent, based on a total weight of the positive electrode.

9. A method of manufacturing a positive electrode, the method comprising,

providing a positive active material, wherein the positive active material comprises particles having an average particle diameter of 1 μm to 30 μm;

providing a first solid electrolyte, wherein the first solid electrolyte comprises particles having an average particle diameter of 0.1 μm to 4 μm; and

pressing the positive active material and the first solid electrolyte particles with a pressure of 50 megaPascals to 600 megaPascals to provide the positive electrode of claim 1 .