Oxygen vacancies and N‐doping in organic–inorganic pre‐intercalated vanadium oxide for high‐performance aqueous zinc‐ion batteries

Pre-intercalation of metal ions into vanadium oxide is an effective strategy for optimizing the performance of rechargeable zinc-ion battery (ZIB) cathodes. However, the battery long-lifespan achievement and high-capacity retention remain a challenge. Increasing the electronic conductivity while simultaneously prompting the cathode diffusion kinetics can improve ZIB electrochemical performance. Herein, N-doped vanadium oxide (N-(Zn,en)VO) via defect engineering is reported as cathode for aqueous ZIBs. Positron annihilation and electron paramagnetic resonance clearly indicate oxygen vacancies in the material. Density functional theory (DFF) calculations show that N-doping and oxygen vacancies concurrently increase the electronic conductivity and accelerate the diffusion kinetics of zinc ions. Moreover, the presence of oxygen vacancies substantially increases the storage sites of zinc ions. Therefore, N-(Zn,en)VO exhibits excellent electrochemical performance, including a peak capacity of 420.5 mA h g(-1) at 0.05 A g(-1), a high power density of more than 10 000 W kg(-1) at 65.3 Wh kg(-1), and a long cycle life at 5 A g(-1) (4500 cycles without capacity decay). The methodology adopted in our study can be applied to other cathodic materials to improve their performance and extend their practical applications.