Composite cathode material β-LiVOPO4/LaPO4 with enhanced electrochemical properties for lithium ion batteries

Abstract

A composite cathode material, β-LiVOPO₄/LaPO₄, is synthesized by a sol–gel method. The synthesized samples are characterized by XRD, SEM, TEM, EDS, XPS, and electrochemical tests. Results indicate that LiVOPO₄ has an orthorhombic structure with a Pnma space group and that LaPO₄ has a monazite structure with a P2₁/n space group. EDS and TEM results illustrate that LaPO₄ with typical sizes of 10–40 nm is homogeneously distributed on the surface of primary LiVOPO₄ particles. The synthesized β-LiVOPO₄/LaPO₄ exhibits much better electrochemical performance than bare β-LiVOPO₄. The β-LiVOPO₄/LaPO₄ samples delivered an initial discharge capacity of about 127.0 mA h g⁻¹ at 0.1 C and possessed favorable capacities at rates of 0.5 and 1 C. Therefore, surface modification of crystalline LaPO₄ is an effective way to improve the electrochemical performance of β-LiVOPO₄.