Enhanced reversible lithium storage property of Sn0.1V2O5 in the voltage window of 1.5-4.0 V

Sn4+ doped V2O5 (Sn0.1V2O5) sample was synthesized by a sol-gel method and post annealing at 400 degrees C for 1 h in air. The microstructure of the as-prepared the Sn0.1V2O5 was analyzed by XRD, XPS, and SEM. The lithium storage performance of the Sn0.1V2O5 was characterized by CV, EIS, and charge/discharge tests in the voltage window of 1.5-4.0 V (vs. Li/Li+). The results demonstrated that Sn doping can refine the grain size of V2O5, increase V4+ concentration in Sn0.1V2O5, and favor the formation of two-dimensional sheet-like morphology. Compared to undoped V2O5, the Sn0.1V2O5 exhibited significantly enhanced lithium storage performance in the voltage window of 1.5-4.0 V (vs. Li/Li). For example, after 100 cycles at 200 mA g(-1), the Sn0.1V2O5 retained a specific discharge capacity of 135 mAh g(-1), much higher than that (91 mAh g(-1)) of the pure V2O5. In addition, Sn0.1V2O5 exhibited a higher initial coulombic efficiency (98.16%) than the undoped V2O5 (91.05%). The improved lithium storage performance can be attributed to the increased lithium ion diffusion coefficient, enhanced electrochemical reaction reversibility, and decreased electrochemical reaction resistance upon Sn4+ doping.