Preparation and Electrochemical Performance of Li_3V_2(PO_4)_3 cathode materials by Microwave-Heated Sol-Gel Method

摘要

The lithium vanadium phosphate (Li_3V_2(PO_4)_3 solid cathode materials were synthesized by microwave-heated sol-gel method using lithium hydroxide, ammonium metavanadate, phosphate and citric acid as starting materials. The test was conducted with orthogonal experiment method. The optimal conditions for (Li_3V_2(PO_4)_3 synthesis were determined to be microwave heating time of 10 min, microwave power of 700 W, Li/V molar ratio of 3.05:2.0 and pH value(gel solution) of 7.0. The synthesized (Li_3V_2(PO_4)_3 under the optimal conditions demonstrated perfect crystal growth and good electrochemical performance with initial charge/discharge specific capacity of 172.42 mAh·g~(-1)/154.93 mAh·g~(-1) and discharge decay rate of 2.25% after 50 cycles. The lithium ion diffusion coefficient was determined to be 1.434 ×10~(-8) cm~2·s~(-1) by electrochemical impedance spectroscopy and mathematical models derived from simulative equivalent circuit.