Promoting Proton Migration Kinetics by Ni²⁺ Regulating Enables Improved Aqueous Zn-MnO₂ Batteries

The energy storage behaviors of MnO₂ for aqueous Zn-MnO₂ batteries mainly depend on the Zn²⁺/H⁺ intercalation but are limited by poor ion/electron migration dynamics and stability. Herein, a strategy is proposed that promoting proton migration kinetics ameliorates H⁺ storage activity by introducing Ni²⁺ into γ-MnO₂ (Ni-MnO₂). Ni²⁺ can lower the diffusion barrier of H⁺ and selectively induce the ion intercalation, thereby alleviating the electrostatic interaction with the lattice. Moreover, Ni²⁺ enables the adjacent [MnO₆] octahedrons to have better electron conductivity. The Ni-MnO₂ exhibits superior rate performance (nearly four times specific capacity compared with MnO₂) and ultra-long-cycle stability (100% of capacity retention after 11000 cycles at 3.0 A g⁻¹). The calculation indicates that the Ni-MnO₂ allows H⁺ migrate rapidly along the one-dimensional tunnel due to reduction of the activation energy caused by Ni²⁺ regulating, thus achieving excellent reaction kinetics. This work brings great potential for the development of high-performance aqueous Zn-MnO₂ batteries.