Synthesis and Performance of Cr Doped Li₃V₂(PO₄)₃/C Cathode Materials for Li Ion Batteries

A series of Cr-doped Li3V2-xCrx(PO4)(3)/C (x = 0.00, 0.10, 0.15, 0.20) composites was synthesized using Sol-gel method. The influence of Cr doping on the structure, morphology and electrochemical performance of Li3V2(PO4)(3)/C were studied. The X-ray diffraction patterns indicate that all of the samples are consistent with those of monoclinic Li3V2(PO4)(3), indicating that Cr3+ can be successfully doped into the lattice of Li3V2(PO4)(3). Scanning electron microscopy, transmission electron microscopy mages revealed the morphology and the uniform distribution of Cr in the samples. In the potential range of 3.0-4.3 V, the Li3V1.9Cr0.1(PO4)(3)/C composite exhibited the highest discharge capacity of 125.1 mAh/g at 0.1 C, while the Li3V1.8Cr0.2(PO4)(3)/C performed a capacity of 95.8 mAhg(-1) with a high capacity retention ratio of 91.6% after 40 circles, which is still lower than the capacity of the Li3V1.9Cr0.1(PO4)(3)/C. Based on the excellent electrochemical performance, Li3V1.9Cr0.1(PO4)(3)/C will be a promising cathode material for rechargeable lithium-ion batteries.