Quenching method introduced oxygen defect type Zn2V2O7·2H2O for long-life aqueous zinc ion batteries

Abstract

Cost-effective and environment-friendly aqueous zinc ion batteries (AZIBs) are ideal for emerging energy storage. Focusing on enhancing the rate performance and cycling stability of AZIBs, various metal oxides and compounds as cathode materials have drawn extensive attention. The development of high-performance AZIBs cathode materials requires concentrating on the Zn²⁺ intercalation strategy and exploring new materials more suitable for Zn²⁺ intercalation to ensure more stable Zn²⁺ storage. Additionally, a straightforward synthesis process considering economic effects and cost issues is essential. Herein, we introduce abundant oxygen vacancies on/near the surface of V₂O₅ by quenching at high temperatures to provide more insertion sites for Zn²⁺. Then, Zn₂V₂O₇·2H₂O with oxygen vacancies is synthesized by reacting V₂O₅ with ZnCl₂ through stirring and subsequent hydrothermal treatment (named QH ZVO). QH ZVO has a tunnel-like structure for stable Zn²⁺ storage, combined with oxygen vacancy defects, enriches Zn²⁺ storage quantity. Density functional theory simulations show that the quenching induced oxygen vacancy narrows the energy band gap of QH ZVO and accelerates electron transfer. The maximum specific capacity reaches 78.34 mAh g⁻¹ at 15 A g⁻¹ with 74.47 % capacity retention after 15,000 cycles. This work offers a new approach for efficient zinc storage and enhances the electrochemical stability of AZIBs.