关键词: 锂离子电池, 流变相法, LiVOPO4, 倍率性能, 扩散系数

Abstract:

A novel lithium-ion battery cathode material, nano-LiVOPO4, was synthesized by a new rheological phase method. The microstructure, surface morphology, and electrochemical properties were characterized by various electrochemicalmethods in combination withX-ray diffraction (XRD) and scanning electron microscopy (SEM). Results show that the orthorhombic LiVOPO4, obtained by this rheological phase method, is made up of 10-60 nm particles. The first discharge capacity, charge capacity, and columbic efficiency of LiVOPO4 were found to be 135.7 mAh·g-1, 145.8 mAh·g-1, and 93.0%, respectively. After 60 cycles, the discharge capacity remained 134.2 mAh·g-1, at 98.9% of the first discharge capacity, and the capacity loss per cycle was only 0.018%at 0.1C (1C=160 mA·g-1).More than 96.5% and 91.6% of the discharge capacity at 0.1C were maintained at 1.0C and 2.0C, respectively. The charge transfer resistance increased with the increase of the cycle number and the diffusion coefficient of lithium ion in the nano-LiVOPO4 was in the order of 10-11 cm2·s-1. Experimental results suggest that the rheological phase method is a good route for the synthesis of LiVOPO4 cathode material of high capacity, good cycling performance, and good current rate capability for lithiumion batteries.

Key words: Lithium ion battery, Rheological phase method, LiVOPO4, Current rate capability, Diffusion coefficient