A facilely-synthesized polyanionic cathode with impressive long-term cycling stability for sodium-ion batteries.

In this work, nanoflower-like Na0.5VOPO4·2H2O with a large interlayer distance of 6.5295 Å is synthesized via a simple chemical precipitation method at room temperature. It is the first time that the potential of the Na0.5VOPO4·2H2O electrode as a cathode material for SIBs has been investigated, and it exhibits a high specific capacity (127 mA h g-1 at 0.2C), outstanding long-term cycling stability and superior reaction kinetics.