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

摘要:

采用液相法合成了Li3V2(PO4)3 (空间群P21/n)电活性材料。用XRD和恒流充放电对样品的微观结构和电化学性能进行了表征。结果表明，在1.5~4.3 V电压范围内，样品在平均电压为1.81和3.77 V时均发生了可逆的锂嵌入反应；锂嵌出和嵌入过程中均出现一系列复杂的相变。在1.5~3.0 V电压范围内，以C/5倍率循环50周后，样品的容量衰减极小，表明锂脱嵌反应具有优良的循环稳定性。因此，Li3V2(PO4)3可以同时作为正极和负极而组成对称电池。另外，1.5~4.3 V电压范围内进行的嵌锂反应可以充当一种内置的过充电安全阀

Abstract:

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