Electrochemical properties of Cr doped V2O5 between 3.8 V and 2.0 V

Cr0.1V2O5.15 was prepared by an oxalic acid assisted sol–gel method. X-ray diffraction showed that Cr doping induced a slight expansion (ΔV/V ≈ 2.3%) in the crystal lattice of V2O5. The electrochemical properties of Cr0.1V2O5.15 in the potential range of 3.8–2.0 V were studied by cyclic voltammetry, galvanostatic charge–discharge cycling and potentiostatic intermittent titration technique. Cyclic voltammetry showed that the irreversible phase transition of V2O5 during the first cycle was effectively prevented by Cr doping. This caused the good charge–discharge cycling performance of the doped material. The discharge capacities were recorded to be 200, 170 and 120 mAhg− 1 after fifty cycles at the C/10, C/2 and 1C rates, respectively. However, ex-situ X-ray diffraction showed that the crystal structure of the material was destroyed after long-term cycling. The lithium diffusion coefficient of Cr0.1V2O5.15 varied between 10− 11 and 10− 12 cm2 s− 1, which was larger than that of crystalline V2O5, and was close to those of metal doped V2O5 in previous reports. The improvement in lithium diffusion kinetics was regarded as an important reason for the good electrochemical performance of Cr0.1V2O5.15.