Layer-by-layer stacked vanadium nitride nanocrystals/N-doped carbon hybrid nanosheets toward high-performance aqueous zinc-ion batteries.

Abstract

Aqueous zinc ion batteries (AZIBs) hold great potential in large scale, low-cost energy storage. Unfortunately, their development is limited by the poor performing cathode materials due to their unstable structures and low capacities. Hence, we develop novel layer-by-layer stacked vanadium nitride nanocrystals/N-doped carbon hybrid nanosheets (VN/NC) as cathode materials by in situ thermal conversion of pyrolyzing pentyl viologen intercalated V2O5. The combination of a leaf-like morphology, the nano structure of vanadium nitride crystals and the conductive porous nitrogen-doped carbon nanosheets endow the VN/NC cathode with excellent electrochemical performance in AZIBs. Thus, it delivers a high discharge specific capacity of 566 mA h g-1 at a current density of 0.2 A g-1 and a superior rate capability. Most importantly, it exhibits a remarkable cyclic stability with capacity retention of 131 mA h g-1 (85% of the initial capacity) after 1000 cycles at a current density of 10 A g-1. The design of the unique VN/NC hybrid nano sheets offers a pathway towards developing high performance electrode materials for energy storage.