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

Abstract

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)mAhg−1 and maintains a stable capacity of 226(±3)mAhg−1 within 50 cycles at the charge–discharge rate of 0.1C and in the voltage range of 1.8–4.0V. 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.