RESUMEN

The development of aqueous zinc-ion batteries (AZIBs) still faces a huge challenge due to poor cycling stability and slow kinetics of the cathode material. In this work, we report an advanced cathode of Ti4+/Zr4+ as dual-supporting sites in Na3V2(PO4)3 with an expanded crystal structure, exceptional conductivity, and superior structural stability for AZIBs, which exhibits fast Zn2+ diffusion and excellent performance. The results of AZIBs afford remarkably high cycling stability (91.2% retention rate over 4000 cycles) and exceptional energy density (191.3 W h kg-1), outperforming most Na+ superionic conductor (NASICON)-type cathodes. Furthermore, different in/ex situ characterization techniques and theoretical studies reveal the reversible storage mechanism of Zn2+ in an optimal Na2.9V1.9Ti0.05Zr0.05(PO4)3 (NVTZP) cathode and demonstrate that Na+ defects together with Ti4+/Zr4+ sites can intrinsically contribute to the high electrical conductivity and low Na+/Zn2+ diffusion energy barrier of NVTZP. Moreover, the flexible soft-packaged batteries further demonstrate a superior capacity retention rate of 83.2% after 2000 cycles from the perspective of practicality.