Sodium vanadate microflowers as cathode for high-capacity and long-life aqueous zinc-ion battery

Abstract

Aqueous zinc-ion batteries (ZIBs) have become increasingly popular in energy storage devices on account of their high safety, low cost, high theoretical specific capacity and low redox potential. However, the practical application of ZIBs has been hindered by cathode materials that usually exhibit low capacity or poor cycling performance. In our work, sodium vanadium oxide (NaV8O20) microflowers with nanosheet structure were prepared by hydrothermal method. As cathode materials of ZIBs, NaV8O20 microflowers deliver a high initial specific capacity of 427.6 mAh g−1 at 0.1 A g−1. Surprisingly, the capacity retention rate is about 77% after 7000 cycles at a high current density of 15 A g−1. These excellent electrochemical performances can be attributed to the pre-intercalation of Na+ ions to enhance the electrode stability and the nanosheet structure to increase the number of active sites, indicating that the aqueous ZIBs based on NaV8O20 microflowers has potential application value for large-scale energy storage.