Synergistic Effect of Composite V₂O₅/Ca_0.17V₂O₅ Film Electrodes as High-Performance Cathodes of SIBs

TheV(2)O(5)/Ca0.17V2O5 film electrodes on indium-doped tin oxide (ITO) conductiveglasses were synthesized by a low-temperature liquid-phase depositionmethod and thermal treatment. The deposited film electrodes were directlyused as cathodes for sodium-ion batteries without additional media.X-ray diffraction and high-resolution transmission electron microscopyresults demonstrated that V2O5/Ca0.17V2O5 films were successfully formed. The ionsdiffusion, electrode reaction kinetics, capacity, and cyclic performancewere revealed by cyclic voltammetry, electrochemical impedance spectroscopy,and galvanostatic charge/discharge measurements. The V2O5/Ca0.17V2O5 film delivereda discharge capacity of 148.465 mAh m(-2) at 1 C rate,which was larger than 100.086 mAh m(-2) of the pureV(2)O(5) film. Moreover, the V2O5/Ca0.17V2O5 film exhibitedan initial discharge capacity of 144.712 mAh m(-2) (90.11% retained after 100 cycles) at a 1 C rate and 112.525 mAhm(-2) (103.91% retained after 100 cycles) at a 2 Crate. Encouragingly, the rate performance was worthy of mention, whichindicated a good reversibility. The impressive electrochemical abilitycould be attributed to the synergistic effect of two phases. The ex-situX-ray diffraction and X-ray photoelectron spectroscopy results provedthat the Ca0.17V2O5 supported thestability of the structure, and the V2O5 phaseacted as a host material for ions insertion/extraction. This workmay provide a promising strategy for developing high-performance electrodematerials.