Electrochemically grown nanocrystalline V2O5 as high-performance cathode for sodium-ion batteries

Abstract Nanocrystalline V 2 O 5 with a bilayer structure is directly grown on a steel substrate electrochemically in VOSO 4 -based solution as a cathode for sodium-ion batteries. No complicated slurry preparation procedure, involving polymer binder and conducting agent additions, is needed for this electrode synthesis. The incorporation of NaCH 3 COO in the VOSO 4 solution promotes oxide growth and improves oxide film uniformity. The interlayer distance between two-dimensional V 2 O 5 stacks in the structure is as large as ∼11.6 A, which is favorable for accommodating Na + ions. The growth potential is critical to determine the oxide architectures and thus the corresponding Na + storage properties (in terms of capacity, high-rate capability, and cycling stability). An optimal charge–discharge capacity of 220 mAh g −1 is achieved for V 2 O 5 grown in an activation-controlled potential region (i.e., 0.8 V vs. an Ag/AgCl reference electrode). This V 2 O 5 electrode shows only 8% capacity decay after 500 cycles.