Achieving high-performance aqueous Zn-ion storage through strong hydrogen bonding and charge redistribution by in-situ induced insertion of non-metallic ion clusters

Pre-insertion of metal cations usually improves the electrochemical performance of aqueous zinc-ion batteries. However, in-situ insertion of non-metal ions clusters remains a challenge. Herein, non-metallic ions clusters were induced into δ-MnO2 by an applied electric field activation strategy in NH4F solution. When a negative electric field is applied to δ-MnO2, the attraction of the negative voltage to NH4+ ions result in the insertion of NH4+ into the interlayers of the δ-MnO2 lattice. Differently, the F- and NH4+ simultaneously enter the lattice interlayers of δ-MnO2 through the configuration of the ion clusters when the applied electric field is positive. In response, the inserted F- ions change the electronic structure of MnO2, making it more difficult for Mn atoms to dissolve out during the charging and discharging process. The intercalated NH4+ ions generate strong hydrogen bonding interactions with the surrounding O atoms, which mitigate the disruption of the MnO2 layered structure during the charging and discharging process. This facile strategy illustrated in this paper can offer new insights into the rational design of electrodes for efficient and stable Zn-ion batteries.