Characterization and Electrochemical Properties of Carbon Decorated Li3V2(PO4)3 Prepared by Citric Acid Assisted Gel and Heat Treating

Abstract

Li₃V₂(PO₄)₃ (LVP) is a prospective cathode material meeting the uninterrupted requirements due to the high theoretical capacity and operating voltage. Nevertheless, the electrochemical capability of pristine LVP is severely restricted under a high operating voltage. Herein, carbon decorated LVP was prepared through the process of citric acid assisted gel and subsequent heat treating. The crystalline phase, morphology, microstructure, and composition of obtained materials were examined using different methods. Transmission electron microscopy result exhibits that the crystalline LVP surface is coated with an amorphous carbon layer of about 3–5 nm thickness, and the LVP particles are connected by carbon. The electrochemical capability of LVP cathode at a cut-off voltage of 4.8 V was determined. The results exhibit the discharge capacity of carbon decorated LVP at 1 C decreases slowly from the initial 132.0 to 104.1 mA h g^–1 after 200 cycles. Correspondingly, the carbon decorated LVP delivers 78.9% capacity retention, which is much larger than that of pristine LVP (46.6%), suggesting the enhanced stability. In addition, the rate and Coulombic efficiency of carbon decorated LVP are also obviously enhanced compared to the pristine LVP. The work verifies a simple modification method to ameliorate the inherent drawbacks and electrochemical properties of LVP at high voltage.