Better than crystalline: amorphous vanadium oxide for sodium-ion batteries

Amorphous and nanocrystalline vanadium pentoxide (V2O5) were prepared through a combination of sol–gel processing paired with electrochemical deposition and investigated as cathodes for sodium-ion batteries. Amorphous V2O5 demonstrated superior electrochemical properties upon sodiation as compared to its crystalline counterpart. More specifically, amorphous vanadium pentoxide had a measured capacity of 241 mA h g−1, twice the capacity of its crystalline contemporary at 120 mA h g−1. In addition, the amorphous vanadium pentoxide demonstrated a much higher discharge potential, energy density, and cycle stability. The development of amorphous materials could enable the usage and design of previously unexplored electrode materials; herein, the possible relationship between the improved sodiation properties and the amorphous structure is discussed.