Positive electrode for lithium-ion secondary battery, and lithium-ion secondary battery

1. A positive electrode for a lithium-ion secondary battery, the positive electrode comprising:

a positive electrode particle comprising

a positive active material comprising a lithium salt, and

a coating layer comprising an amorphous carbonaceous layer on a surface of the positive active material; and

a sulfide solid electrolyte contacting the coating layer, wherein the sulfide solid electrolyte comprises a solid sulfide,

wherein the coating layer comprises a diamond-like carbon,

wherein the coating layer comprises hydrogen atoms, and

wherein an amount of the hydrogen atoms is in the range of about 1 atomic percent to about 50 atomic percent, based on a total content of the coating layer.

2. The positive electrode for a lithium-ion secondary battery of claim 1 , wherein the coating layer comprises an aliphatic hydrocarbon, an aromatic hydrocarbon, or a combination thereof.

3. The positive electrode for a lithium-ion secondary battery of claim 1 , wherein the coating layer comprises a deposition product of acetylene, methane, benzene, toluene, xylene, naphthalene, cyclohexane, or a combination thereof.

4. The positive electrode for a lithium-ion secondary battery of claim 1 , wherein the coating layer comprises a deposition product of an alicyclic hydrocarbon of the formula C 4n+6 H 4n+12 , where n is a positive integer.

5. The positive electrode for a lithium-ion secondary battery of claim 1 ,

wherein the coating layer comprises sp 2 hybridized carbon atoms and sp 3 hybridized carbon atoms, and

wherein a content of the sp 3 hybridized carbon atoms in the coating layer is in the range of about 10% to about 100%, based on a total carbon content of the coating layer.

6. The positive electrode for a lithium-ion secondary battery of claim 1 , wherein the coating layer is formed by plasma-enhanced chemical vapor deposition or physical vapor deposition.

7. The positive electrode for a lithium-ion secondary battery of claim 1 , wherein the sulfide solid electrolyte is in a form of particles.

8. The positive electrode for a lithium-ion secondary battery of claim 1 , wherein the sulfide solid electrolyte comprises sulfur and lithium, and further comprises phosphorus (P), silicon (Si), boron (B), aluminum (Al), germanium (Ge), zinc (Zn), gallium (Ga), indium (In), a halogen element, or a combination thereof.

9. The positive electrode for a lithium-ion secondary battery of claim 1 , wherein the sulfide solid electrolyte comprises

lithium sulfide; and

silicon sulfide, phosphorus sulfide, boron sulfide, or a combination thereof.

10. A lithium-ion secondary battery comprising:

a positive electrode layer comprising a positive electrode particle comprising

a positive active material comprising a lithium salt, and

a coating layer comprising an amorphous carbonaceous layer on a surface of the positive active material;

a negative electrode layer comprising a negative active material; and

a sulfide solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the sulfide solid electrolyte layer comprises a sulfide solid electrolyte comprising a solid sulfide,

wherein the coating layer comprises a diamond-like carbon,

wherein the coating layer comprises hydrogen atoms, and

wherein an amount of the hydrogen atoms is in the range of about 1 atomic percent to about 50 atomic percent, based on a total content of the coating layer.

11. The lithium-ion secondary battery of claim 10 , wherein the coating layer comprises a deposition product of an aliphatic hydrocarbon, an aromatic hydrocarbon, or a combination thereof.

12. The lithium-ion secondary battery of claim 10 , wherein the coating layer comprises a deposition product of acetylene, methane, benzene, toluene, xylene, naphthalene, cyclohexane, or a combination thereof.

13. The lithium-ion secondary battery of claim 10 , wherein the coating layer comprises a deposition product of an alicyclic hydrocarbon of the formula C 4n+6 H 4n+12 , where n is a positive integer.

14. The lithium-ion secondary battery of claim 10 , wherein the coating layer consists of the diamond-like carbon.

15. The lithium-ion secondary battery of claim 10 , wherein the coating layer comprises sp 2 hybridized carbon atoms and sp 3 hybridized carbon atoms, and a content of the sp 3 hybridized carbon atoms in the coating layer is in the range of about 10% to about 100%, based on a total carbon content of the coating layer.

16. The lithium-ion secondary battery of claim 10 , wherein the positive active material comprises a lithium salt of a transition metal oxide having a layered rock-salt type structure.

17. The lithium-ion secondary battery of claim 16 , wherein the lithium salt of the transition metal oxide having a layered rock-salt type structure is LiNi x Co y Al z O 2 or LiNi x Co y Mn z O 2 , where 0<x<1, 0<y<1, 0<z<1, and x+y+z=1.

18. The lithium-ion secondary battery of claim 10 , wherein the sulfide solid electrolyte comprises sulfur and lithium, and further comprises phosphorus (P), silicon (Si), boron (B), aluminum (Al), germanium (Ge), zinc (Zn), gallium (Ga), indium (In), a halogen element, or a combination thereof.

19. The positive electrode for a lithium-ion secondary battery of claim 1 , wherein a content of sp 3 hybridized carbon atoms in the coating layer is in a range of about 30% to about 70%, based on a total carbon content of the coating layer.

20. The positive electrode for a lithium-ion secondary battery of claim 19 , wherein a ratio of the sp 2 hybridized carbon atoms to sp 3 hybridized carbon atoms in the coating layer is in a range of about 40:60 to about 60:40, based on a total carbon content of the coating layer.

21. The positive electrode for a lithium-ion secondary battery of claim 1 , wherein the coating layer consists of the diamond-like carbon.