Preparation of Ga-doped lithium trivanadates as cathode materials for lithium-ion batteries

A series of gallium-doped lithium trivanadates, LiV3-xGaxO8 (x = 0.00. 0.02, 0.04, 0.06, and 0.08), were prepared as cathode materials by a sol-gel method. The characterizations of the crystal structures and microstructures were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) mapping. Charge-discharge cycling performance. cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were also used to characterize their electrochemical properties. The charge-discharge tests show that the electrochemical performance of LiV3O8 improved with Ga3+ doping and that LiV2.94Ga0.06O8 has the best electrochemical properties, exhibits a high discharge capacity of 277 (+/- 3) mAh g(-1) and maintains a stable capacity of 226 (+/- 3) mAh g(-1) within 50 cycles at the charge-discharge rate of 0.1 C and in the voltage range of 1.8-4.0 V. The LiV2.94Ga0.06O8 electrode also shows better electrochemical performances at higher rates. The EIS results show that both the charge-transfer resistance and the resistance of the lithium ion diffusion decreased greatly after doping, which is favorable for fast lithium-ion intercalations/deintercalations in bulk materials. (C) 2011 Elsevier Ltd. All rights reserved.