Study on the Structural and Surface Changes during Lithiation/Delithiation Processes in Copper Sulfide

Rechargeable batteries have been considered as one of efficent routes for energy conversion and storage. Li-ion batteries (LIBs) have been empolyed as major power sources for both mobile and stationary and applications. However, the energy densities of conventional, intercalation-based LIBs are insufficient to meet the demands for high-energy-densities enabling long distance driving electric vehicles and large-scale energy storage [1]. Transition metal sulfides based on conversion and/or alloying reactions have drawn considerable interest due to their abundance and high specific capacities [2]. Among them, copper sulfide (CuS) has a theoretical capacity of 560 mAh g -1 (CuS + 2Li + + 2e ‒ ↔ Li 2 S + Cu) and good electronic conductivity of ~10 -3 S cm -1 [3,4]. Nevertheless, CuS shows poor cycling stability, owing to the dissolution of lithium polysulfides (Li 2 S n , 2