Mechanically robust and conductive Ti5Te4/P@C composite materials as promising lithium-ion battery anodes

Abstract

An urgent need has emerged to develop lithium-ion battery anodes that exhibit high reversible capacity and rate performance surpassing carbonaceous materials. Si-based composites have been investigated extensively. However, in this study, we explored another potential alloy anode consisting of Te and phosphorus without Si. Herein, we present a novel composite material, Ti5Te4/P@C, as an anode for lithium-ion batteries (LIBs). Tellurium, which exhibits good electrical conductivity and high volumetric capacity, and red phosphorus, which exhibits high theoretical capacity, were selected as potential anode materials. To overcome the common drawbacks of the two materials, including the vigorous expansion of volume, electrochemically inactive materials, such as titanium and carbon, were introduced as matrix buffers. Te, Ti, red phosphorus, and C were synthesized using a three-step high energy ball milling (HEBM) technique, that is, stepwise synthesis of (1) Ti and Te, (2) red phosphorus, and (3) carbon. The developed Ti5Te4/P@C composites revealed that the introduction of red P led to the generation of additional pure Te in the Ti5Te4/P@C composites, which was owing to the different binding interactions between Ti, Te, and red P, as confirmed by DFT calculations. Among the developed Ti5Te4/P@C anodes, Ti5Te4/P(30 wt%)@C exhibited outstanding cyclability and high rate performance (440 mAh g−1 at 300 mA g−1 after 500 cycles). To confirm the electrochemical responses and Li+ ion diffusion mechanisms, CV and GITT analyses were performed. Based on the electrochemical characteristics, the superior electrochemical performance of the Ti5Te4/P@C anodes can be ascribed to the well-defined composite structure, including the high electrical conductivity of Te, high theoretical capacity of red P, and effective buffering agents of Ti as a mechanical supporter and conductive C, which enable a pseudocapacitive response, providing better reversibility. Therefore, the Ti5Te4/P@C composite materials are viable anodes for high-performance LIBs.