Stable high-rate cycling electrode based on Li3V2(PO4)3/C using polyamide as a novel carbon source

Abstract

Polyamide, as a novel carbon source, was introduced for the first time into the synthesis of Li₃V₂(PO₄)₃/C cathode materials for lithium ion batteries through a carbon-thermal reduction method. The influence of different sintering temperatures on crystal structure, morphology and electrochemical performance of the Li₃V₂(PO₄)₃/C composites was investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electrochemical tests. XRD results indicate that as-prepared Li₃V₂(PO₄)₃ is a well crystallized single phase without any impurity phase. SEM and TEM observation demonstrates that a uniform carbon layer with a thickness of about 2–3 nm is coated on Li₃V₂(PO₄)₃ particles. The optimal Li₃V₂(PO₄)₃/C composite synthesized at 800 °C exhibits a specific capacity of 125.5 mA h g⁻¹ at 1C rate and 94.7% capacity retention when the rate increases from 1C to 10C, presenting a good rate capability. The cross-linking effect of residual carbon from decomposed polyamide plays a critical role in decreasing electron transfer resistance and improving the lithium ion diffusion behavior in Li₃V₂(PO₄)₃ particles.