Synthesis and improved electrochemical performances of porous Li 3V 2(PO 4) 3/C spheres as cathode material for lithium-ion batteries

Abstract

Spherical Li 3V 2(PO 4) 3/C composites are synthesized by a soft chemistry route using hydrazine hydrate as the spheroidizing medium. The electrochemical properties of the materials are investigated by galvanostatic charge–discharge tests, cyclic voltammograms and electrochemical impedance spectrum. The porous Li 3V 2(PO 4) 3/C spheres exhibit better electrochemical performances than the solid ones. The spherical porous Li 3V 2(PO 4) 3/C electrode shows a high discharge capacity of 129.1 and 125.6 mAh g −1 between 3.0 and 4.3 V, and 183.8 and 160.9 mAh g −1 between 3.0 and 4.8 V at 0.2 and 1 C, respectively. Even at a charge–discharge rate of 15 C, this material can still deliver a discharge capacity of 100.5 and 121.5 mAh g −1 in the potential regions of 3.0–4.3 V and 3.0–4.8 V, respectively. The excellent electrochemical performance can be attributed to the porous structure, which can make the lithium ion diffusion and electron transfer more easily across the Li 3V 2(PO 4) 3/electrolyte interfaces, thus resulting in enhanced electrode reaction kinetics and improved electrochemical performance.