Preparation and electrochemical performances of rod-like LiV₃O₈/carbon composites using polyaniline as carbon source

Abstract

Rod-like LiV₃O₈/carbon composites were successfully prepared by the polymer graphitization of LiV₃O₈/polyaniline composites, which were synthesized through the in-situ oxidative polymerization method. The crystal phases of as-prepared samples, confirmed by X-ray diffraction, show that the interlayer spacing in LiV₃O₈/carbon composites is much wider than that of the pristine LiV₃O₈. Compared to the bare LiV₃O₈, the longer and smoother rod-like LiV₃O₈/carbon composites, investigated by scanning electron microscope and transmission electron microscope, were covered by a continuously thin layer of fluffy carbon with a thickness of approximate 20 nm. The optimal LiV₃O₈/carbon composite delivered a discharge capacity of 219.37 mAh g⁻¹ in the initial cycle, and maintained a high capacity of 263.538 mAh g⁻¹ at the 30th cycle, which was much higher than that of the pristine LiV₃O₈ (227.645 mAh g⁻¹). Cyclic voltammetry measurements disclose that, after the carbon coating treatment, the phase transition of the optimal LiV₃O₈/carbon composite proceeds more reversibly and smoothly during charging/discharging. The improved cyclability of the optimal LiV₃O₈/carbon composite should be attributed to the confinement from thin carbon layer, the structural stability, the good interfacial compatibility, and the well-preserved electrode morphology after prolonged cycles.