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

Abstract

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 (∼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 expansion 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.