Effects of thermal annealing on the Li+ intercalation properties of V2O5•nH2O xerogel films

V(2)O(5)(.)nH(2)O xerogel films with n = 1.6, 0.6, and 0.3 have been prepared from the sol-gel route by reacting V2O5 with H2O2 followed by drying under ambient conditions and thermal annealing at 110 and 250 degrees C, respectively. After dehydration, V2O5 crystallizes at 300-330 degrees C, as revealed by thermal gravimetric analysis and X-ray diffraction. Electrochemical characterization demonstrated that V2O5-0.3H(2)O film exhibits the best Li+ intercalation performance, with an initial capacity of 275 mAh/g and a stabilized capacity of 185 mAh/g under a high current density of 100 mu A/cm(2) after 50 cycles. Under a low current density of 10 mu A/cm(2), the capacity of this film can reach 390 mAh/g. Such an enhanced electrochemical property by thermal treatment is ascribed to the. reduced water content, the retained interlayer spacing, and the dominant amorphous phase in the film.