Sol-Gel Synthesis and Electrochemical Performance of Li_3V_(2-2x/3)Mn_x(PO_4)_3 Cathode Material for Lithium-ion Batteries

Novel cathode material Li3V2-2x/3Mnx(PO4)3/C was successfully synthesized by Sol-Gel method using CH3COOLi·2H2O,V2O5,Mn(CH3COO)2·4H2O,(NH4)2HPO4 and sucrose as raw materials.The as-prepared products were characterized by XRD,XPS,SEM.The results show that a small amount of Mn2+doping do not alter the structure of Li3V2(PO4)3 materials with a monoclinic structure(space group P21/n),and the valence states of V and Mn in Li3V1.94Mn0.09(PO4)3/C are +3 and +2,respectively.The Li3V1.94Mn0.09(PO4)3 particle with uniform shape of sphere and diameter less than 200 nm,shows the best cyclic stability and rate performance.Controlling the charge and discharge voltage range from 3.0 to 4.8 V at the rate of 0.1C,the first charge and discharge capacity of Li3V1.94Mn0.09(PO4)3 are up to 182.1 and 168.8 mAh/g,respectively,and its discharge efficiency is up to 92.69%.After 100 cycles,its discharge capacity can also retain 77.4% of the first one.