Integration of homologous vanadium oxide and nitride with adjustable interfacial strain and charge for high performance cathode aqueous zinc-ion batteries.

The poor stability and slow kinetics of VO-based electrodes present significant challenges for their implementation in aqueous zinc-ion batteries (ZIBs). Herein, a homologous 2VO-3VN heterostructure was fabricated through metal-assisted etching and hydrothermal reaction. The metal-assisted etching creates spatial channels that facilitate rapid ion and electron transport. Additionally, the interfacial strain induced by the hybridization of vanadium nitride significantly stabilizes the layered structure and enhances electron mobility, enabling highly reversible zinc-ion storage and improved reaction kinetics. The resultant 2VO-3VN heterostructure as a cathode material demonstrates a high reversible capacity of 398 mA h g at 0.1 A g, a remarkable rate capability of 103.2 mA h g at 4 A g, and outstanding cycling stability (125 mA h g at 4 A g with 83 % capacity retention after 1000 cycles). Furthermore, ex-situ XRD and ex-situ XPS analyses confirm the effective intercalation and deintercalation of Zn ions, as well as the structural reversibility of 2VO-3VN electrode during charge-discharge processes, highlighting its superior Zn ions storage capabilities and long-term cycling stability. This study elucidates the fundamental principles of strain engineering in homologous vanadium-based heterostructures, providing valuable insights for designing advanced vanadium-based composite materials toward energy storage.