Tang Anping

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

Abstract The electroactive lithium vanadium phosphate, monoclinic Li 3 V 2 (PO 4 ) 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 Li 3 V 2 (PO 4 ) 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.

Electrochemical Performance of LiMnBO3/C Composite Synthesized by Wet Impregnating Method

Abstract Hexagonal-LiMnBO 3 /C composite was prepared by a wet impregnating method using the 3D-network ketchen black (KB) as both a temple and a conductive framework. The crystal structure, morphology and specific surface area were characterized by X-ray diffraction, scanning electron microscopy and nitrogen sorption measurements, respectively. The electrochemical properties of the composite were studied by galvanostatic charge/discharge and cyclic voltammetry measurements. Results show that when tested at C/20 rate for Li ion insertion/extraction properties, LiMnBO 3 /C composite exhibits good cycle capability with discharge capacity retention of 87.4% at the 30th cycle. As the current rate increases from C/20, C/10 to C/5, good rate capability is obtained for all rates with initial discharge specific capacities of 138.8, 124.5 and 100.5 mAh·g −1 , respectively.