New Insight into the Interaction between Carbonate-based Electrolyte and Cuprous Sulfide Electrode Material for Lithium Ion Batteries

Abstract

Cuprous sulfide (Cu2S) is attractive electrode material for lithium-ion battery because of its high capacity and energy density. Interestingly, the cycling stability of cuprous sulfide is poor in the carbonate-based electrolytes used in lithium ion battery industry but excellent in ether-based electrolyte. In this study, we have compared the electrochemical performance of commercially available cuprous sulfide in various kinds of carbonate-based electrolytes. Our results show that the specific capacity of Cu2S electrode fades quickly in cyclic carbonate-based electrolytes, but a much better electrochemical performance in linear carbonate-based electrolytes. In linear carbonate-based electrolyte (1M LiPF6 in EMC), it exhibits a specific discharge capacity of 242.8mAhg−1 after 50 cycles with coulombic efficiency of 99.6%. Our study suggests that the poor cycling performance of Cu2S in cyclic carbonate-based electrolytes is mainly due to the higher reactivity of cyclic carbonates with polysulfides on the surface of the electrode than linear carbonates, which was confirmed for the first time by our experiment studies and theoretical calculation.