Cu2Sb Nano-Alloys Dispersed in TiC-C Hybrid Matrix for Sodium-Ion Batteries

Abstract

A novel nanocomposite system in which Cu2Sb nano-alloys are dispersed in a highly conductive hybrid matrix consisting of titanium carbide (TiC) and carbon, was developed by means of a high energy mechanical milling (HEMM) process. The as-prepared alloy, Cu2Sb-TiC-C, was used as an anode material for sodium-ion batteries. The structure and morphology of the Cu2Sb-TiC-C alloy composites were determined via X-ray diffraction, which revealed the highly crystalline nature of the Cu2Sb and the TiC. In addition, high-resolution transmission electron microscopy revealed that the Cu2Sb nanoparticles are well dispersed in the TiC-C matrix. The Cu2Sb-TIC-C composite anode exhibited stable cyclic performance for up to 60 cycles. In fact, adding fluoroethylene carbonate (FEC) to the electrolyte led to significant improvement of the cyclic performance, as manifested in a 100th-cycle capacity retention of 88%. This enhancement was attributed to the formation of a thin and stable solid electrolyte interphase (SEI) layer, a metal-framework supporting active material, and the highly conductive matrix composed of TiC and C. Furthermore, ex-situ XRD analysis, which was used to determine the Na-storage mechanism, confirmed the formation of the Na3Sb phase during sodiation.