Highly Active and Stable Li<sub>2</sub>S−Cu Nanocomposite Cathodes Enabled by Kinetically Favored Displacement Interconversion between Cu<sub>2</sub>S and Li<sub>2</sub>S
Lulu Tan, Anran Li, Yusi Yang, Jianwen Zhang, Xiaogang Niu, Nan Li, Limin Liu, Lin Guo, Yujie Zhu
Abstract
Abstract The high activation barrier, inferior rate performance, and short cycling life severely constrain the practical applications of the high‐capacity Li 2 S cathode. Herein, we fabricate a Li 2 S−Cu nanocomposite with a drastically reduced activation potential, fast rate capability, and extraordinary cycling stability even under a practically relevant areal capacity of 2.96 mAh cm −2 . Detailed experimental investigations aided by theoretical calculations indicate that instead of converting to S 8 via troublesome soluble lithium polysulfides, Li 2 S is thermodynamically and kinetically more favorable to react with Cu by the displacement reaction, which alters the redox couple from Li 2 S/S to Cu/Cu 2 S, leading to the excellent electrochemical performance. Moreover, the stability of the composite is demonstrated in the full‐cell configuration consisting of commercial graphite anodes. This work provides an innovative and effective approach to realize highly activated and stable Li 2 S cathode materials.