Synergism of preintercalated manganese ions and lattice water in vanadium oxide cathodes for high-capacity and long-life Zn-ion batteries

Aqueous Zn-ion batteries (AZIBs) are recognized as a promising energy storage system with intrinsic safety and low cost, but its applications still rely on the design of high-capacity and stable-cycling cathode materials. In this work, we present an intercalation mechanism-based cathode materials for AZIB, i.e. the vanadium oxide with pre-intercalated manganese ions and lattice water (noted as MVOH). The synergistic effect between Mn2+ and lattice H2O not only expands the interlayer spacing, but also significantly enhances the structural stability. Systematic in-situ and ex-situ characterizations clarify the Zn2+/H+ co-(de)intercalation mechanism of MVOH in aqueous electrolyte. The demonstrated remarkable structure stability, excellent kinetic behaviors and ion-storage mechanism together enable the MVOH to demonstrate satisfactory specific capacity of 450 mA h g−1 at 0.2 A g−1, excellent rate performance of 288.8 mA h g−1 at 10 A g−1 and long cycle life over 20,000 cycles at 5 A g−1. This work provides a practical cathode material, and contributes to the understanding of the ion-intercalation mechanism and structural evolution of the vanadium-based cathode for AZIBs.