Cathode for lithium-sulfur battery and manufacturing method therefor

1. A cathode for a lithium-sulfur battery, comprising:

a cathode active part comprising a sulfur-carbon composite; and

a cathode coating layer provided on at least one portion of a surface of the cathode active part and consisting of an amphiphilic polymer comprising polyvinyl pyrrolidone (PVP), said amphiphilic polymer including a hydrophilic portion and a hydrophobic portion,

wherein the cathode coating layer comprises pores and the pores have an average diameter of 1 nm to 10 μm,

wherein the cathode coating layer has a porosity of 50 to 95% based on a total volume of the cathode coating layer, and

wherein the cathode coating layer has a thickness of 10 nm to 1 μm.

2. The cathode for a lithium-sulfur battery of claim 1 , wherein a hydrophobic portion of the amphiphilic polymer is oriented toward the sulfur-carbon composite.

3. The cathode for a lithium-sulfur battery of claim 1 , wherein a content of the amphiphilic polymer is 0.01 to 10 parts by weight based on 100 parts by weight of the sulfur-carbon composite of the cathode active part.

4. The cathode for a lithium-sulfur battery of claim 1 , wherein the cathode coating layer is provided over an entire portion of a surface of the cathode active part.

5. The cathode for a lithium-sulfur battery of claim 1 , wherein the sulfur-carbon composite is formed by applying sulfur particles on porous carbon.

6. The cathode for a lithium-sulfur battery of claim 1 , wherein the sulfur-carbon composite is formed by dissolving sulfur particles and mixing the sulfur particles with carbon.

7. The cathode for a lithium-sulfur battery of claim 1 , wherein the cathode active part further comprises one or more additives selected from a transition metal element, a Group IIIA element, a Group IVA element, a sulfur compound of these elements, and an alloy of these elements and sulfur.

8. A lithium-sulfur battery comprising:

an anode comprising lithium metal or a lithium alloy as an anode active material;

the cathode for a lithium-sulfur battery of claim 1 ;

a separator provided between the cathode and the anode; and

an electrolyte impregnated in the anode, the cathode, and the separator and comprising a lithium salt and an organic solvent.

9. The lithium-sulfur battery of claim 8 , wherein the lithium salt is one or more selected from the group consisting of LiSCN, LiBr, LiI, LiPF 6 , LiBF 4 , LiSO 3 CF 3 , LiClO 4 , LiSO 3 CH 3 , LiB(Ph) 4 , LiC(SO 2 CF 3 ) 3 , and LiN(SO 2 CF 3 ) 2 .

10. The lithium-sulfur battery of claim 8 , wherein the lithium alloy is an alloy of lithium and a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Al, and Sn.

11. The lithium-sulfur battery of claim 8 , wherein the organic solvent is a single solvent or a mixed organic solvent of two or more solvents.

12. A battery module comprising the lithium-sulfur battery of claim 8 as a unit cell.