@article{Zou2023, 
author = {Jian Zou and Zhenrui Wu and Ruilin Tang and Zhenzhen Ren and Xiaobin Niu and Liping Wang},
title = {Copper diffusion related phase change and voltage decay in CuS cathode},
year = {2023},
journal = {Nano Research},
volume = {16},
number = {6},
pages = {8497-8503},
keywords = {copper sulfides, lithium metal battery, conversion-type materials, copper diffusion, Li-free cathode},
url = {https://www.sciopen.com/article/10.1007/s12274-023-5627-9},
doi = {10.1007/s12274-023-5627-9},
abstract = {Copper sulfide (CuS) is a promising cathode for lithium-ion batteries (LIBs) due to its impeccable theoretical energy density (~ 1015 Wh·kg−1 and 4743 Wh·L−1). However, it suffers from voltage decay leaded energy density loss and low energy efficiency, which hinders its application. In this work, with combined ex-situ/in-situ X-ray diffraction (XRD) and electrochemical analysis, we explore detailed degradation mechanisms. For the voltage decay, it is attributed to a spontaneous reaction between CuS cathode and copper current collector (Cu CC). This reaction leads to energy density loss and active materials degradation (CuS → Cu1.81S). As for energy efficiency, CuS undergoes a series of phase transformations. The main phase transition processes are CuS → α-LiCuS → Li2−xCuxS + Cu → Li2S + Cu for discharge; Li2S + Cu → Li2−xCuxS → β-LiCuS → CuS for charge. Here, α-LiCuS, β-LiCuS, and Li2−xCuxS are newly identified phases. These phase changes are driven by topotactic-reaction-related copper diffusion and rearrangement. This work demonstrates the significance of transition-metal diffusion in the intermediates formation and phase change in conversion-type materials.}
}