Electrochemical Study of Monoclinic Li3V2(PO4)3 in the Voltage Range of 1.5∼3.0 V

The electroactive lithium vanadium phosphate, monoclinic Li3V2(PO4)3 [space group 14(P21/n)] has been synthesized by a solution route. The microstructure and electrochemical properties of the samples were characterized through combination of X-ray diffraction and galvanostatical discharge/discharge. Preliminary electrochemical evaluation indicates that this phosphate undergoes reversible lithium insertion reactions at average potentials of 1.81 and 3.77 V, and a complex series of two-phase transitions were observed during lithium extraction and insertion in the voltage range of 1.5∼4.3 V. Constant current cycling conducted at C/5 and in the voltage range of 1.5∼3.0 V is indicative of the longer term stability of the lithium insertion reactions evidenced by minimal capacity fade over the first 50 charge-discharge cycles. Therefore Li3V2(PO4)3 maybe used as both cathode and anode for fabrication of a symmetric lithium-ion battery, and the lithium insertion in the voltage region of 1.5∼3.0 V could serve as a built-in overdischarge safety valve.