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(DFT)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 10000 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.