Highly conductive and robust telluride-carbon hybrid matrix for enhanced copper diphosphide anode in Li-ion batteries

CuP2 is a phosphorous-rich transition metal phosphide that can be a potential anode for Li-ion batteries (LIBs) because of its high theoretical capacity (similar to 1280 mA h g-1) and intrinsic alleviation of volume change owing to the presence of inactive Cu. Despite these advantages, the electrochemical performance of CuP2 is not satisfactory owing to its low electrical conductivity and insufficient regulation of large volume ex-pansion during cycling. Herein, we propose a CuP2-Te-C ternary composite as a high-performance anode material for LIBs. The presence of Te-C can circumvent the limitations of CuP2, as it can synergistically increase the electrical conductivity while mitigating the cycling instability. The individual roles of Te and C in enhancing the active CuP2 performance were studied using various morphological and electrochemical characterizations. Furthermore, an appropriate C content (25 wt%) that can increase the specific capacity while maintaining cycling stability was determined. Under these conditions, CuP2-Te-C(25 %) displayed a good cycling performance (532 mA h g-1 at 100 mA g-1 after 100 cycles) and rate capability (501 mA h g-1 at 3.0 A g-1). The superior performance of CuP2-Te-C(25 %) studied comprehensively using electrochemical impedance spectroscopy revealed a higher diffusivity and lower charge transfer resistance for CuP2-Te-C(25 %) than its counterparts. This study presents new perspectives on high-performance metal-phosphide anode materials for LIBs.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

CuP2 is a phosphorous-rich transition metal phosphide with high theoretical capacity and intrinsic alleviation of volume change, making it a potential anode material for Li-ion batteries (LIBs). However, its electrochemical performance is limited due to low electrical conductivity and insufficient regulation of volume expansion. In this study, a CuP2-Te-C ternary composite was proposed as a high-performance anode material. The introduction of Te-C can enhance conductivity and mitigate cycling instability. The study comprehensively investigated the roles of Te and C, and determined an appropriate C content (25 wt%) for improved capacity and cycling stability. The CuP2-Te-C(25%) showed good cycling performance and rate capability. Electrochemical impedance spectroscopy analysis revealed its superior diffusivity and lower charge transfer resistance. This study provides new perspectives on high-performance metal-phosphide anode materials for LIBs.