Preparation and Electrochemical Properties of Ceria Coated Li₃V₂(PO₄)₃/C Cathode Materials for Lithium-Ion Batteries

Abstract

Li3V2(PO4)3/C are synthesized by an improved sol-gel method of which pH value is controlled at 4. The powders are then coated with various amounts of CeO2 by a suspension coating process assisted by polyvinyl alcohol. The electrochemical properties of the samples are characterized by galvanostatic charge/discharge test, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and potential step chronoamperometry (PSCA). Galvanostatic electrochemical measurements indicate that 2 wt% CeO2 coated Li3V2(PO4)3/C exhibits the best electrochemical performances in the voltage range of 3.0–4.8 V, especially at high rates. The 2 wt% CeO2 coated sample shows initial discharge capacity of 112.7 mAh g−1 at 5 C, while the discharge capacities of the pristine sample are only 75.2 mAh g−1. And it remains capacity retention of 93.5% at 5 C after 100 cycles, which is much higher than that of Li3V2(PO4)3/C. These improved electrochemical performances can be attributed to the better structural stability and lower charge-transfer resistance resulted from the appropriate amount of CeO2 coating.