Na2V6O16·2.14H2O nanobelts as a stable cathode for aqueous zinc-ion batteries with long-term cycling performance

Aqueous zinc-ion batteries (ZIBs) have been considered as one of the most promising electrochemical devices for large-scale energy storage system owing to their low cost and high safety. Herein, Na2V6O16·2.14H2O nanobelts are synthesized and applied as cathode material for ZIBs. The sample displays a high capacity of 466 mAh g−1 at 100 mA g−1 and stable cycling performance with a capacity retention of 90% over 2000 cycles at the 20 A g−1. Moreover, Na2V6O16·2.14H2O presents a capable rate ability and a high energy density of 312 Wh kg−1 at a specific power of 70 W kg−1. The superior electrochemical performance is attributed to the large interlayer spacing and outstanding structure stability, which promise the highly reversible intercalation and extraction of zinc ion. The electrochemical kinetics and zinc ion storage mechanism are also investigated. This work demonstrates that nanoscale electrode materials with large interlayer spacing can effectively enhance the electrochemical performance of aqueous ZIBs, which can be extended to other metal ion batteries, such as magnesium ion batteries and aluminum ion batteries.