Tri-Functional Copper Sulfide as Sulfur Carrier for High-Performance Lithium-Sulfur Batteries

Copper sulfide/sulfur composite, containing highly dispersed CuS, Cu2S and sulfur, is obtained via a facile one-step reaction of copper chloride and sodium thiosulfate. Based on the total mass of composite, a high initial capacity of 782.4 mAh g−1 with high coulombic efficiency of 97.4% is obtained, and after 50 cycles, the discharge capacity can still be retained at 580.2 mAh g−1. The excellent electrochemical performance can be attributed to the tri-functional copper sulfide in the composite, which is electroactive to offer additional energy storage, high conductive to enhance the sulfur utilization and have strong chemical interactions with polysulfides to prohibit the shuttle effect.