Superior sodium storage performance of additive-free V2O5 thin film electrodes

Abstract

A binder- and conductive-agent-free V₂O₅ thin film electrode was fabricated by a facile and cost-efficient cathodic deposition method directly on stainless steel substrates followed by annealing at 300 °C in air for 1 h. The V₂O₅ film is approximately 1 μm in thickness and consists of layer-by-layer stacked nanosheets. When used as a cathode for sodium ion batteries, the V₂O₅ thin film electrode exhibits a high reversible discharge capacity (174 mA h g⁻¹ at 200 mA g⁻¹), excellent cycling stability (almost 100% capacity retention over 200 cycles at 1 A g⁻¹), and outstanding rate capability (retaining a capacity of 124 mA h g⁻¹ at 5 A g⁻¹). Cyclic voltammetric analyses reveal that pseudocapacity-dominated charge storage of sodium ions accounts for the superior performance.