Hydrated vanadium pentoxide with superior sodium storage capacity

Sodium ion batteries (SIBs), as potential candidates for large-scale energy storage systems, have attracted great attention from researchers. Herein, a V2O5 center dot nH(2)O xerogel composed of thin acicular interconnected nanowire networks has been synthesized via a facile freeze-drying process. The interlayer spacing of V2O5 center dot nH(2)O is larger than that of orthorhombic V2O5 due to the intercalation of water molecules into the layer structure. As the cathode of a SIB, V2O5 center dot nH(2)O exhibits a high initial capacity of 338 mA h g(-1) at 0.05 A g(-1) and a high-rate capacity of 96 mA h g(-1) at 1.0 A g(-1). On the basis of combining ex-situ XRD and FTIR spectroscopy, the Na+ ion intercalation storage reactions are discussed in detail. By modeling calculations, the pseudocapacitive behavior makes a great contribution to the high capacities. Our work demonstrates that V2O5 center dot nH(2)O with large interlayer spacing is a promising candidate for high capacity sodium-based energy storage.