Consecutive core–shell SP@PDA-d-δ-MnO2 cathode material for aqueous zinc-ion batteries

Abstract

Rechargeable aqueous zinc-ion batteries (ZIBs) based on Zn/MnO₂ are highly attractive owing to their low cost, safety, environmental benignity, and elemental abundance. However, the MnO₂ cathode is still insufficiently reversible at a high energy density and under long-life cycling owing to its dissolution–redeposition and low electronic conductivity. In this study, core–shell-structured SP@PDA-d-δ-MnO₂ with consecutive super p cores and an evenly distributed δ-MnO₂ shell was designed and prepared. SP@PDA-d-δ-MnO₂, as a cathode material for aqueous ZIBs, shows a high specific capacity, moderate rate, and cycling properties in a 2.0 M ZnSO₄ aqueous electrolyte. We determined that the continuously connected conductive carbon inside MnO₂ facilitates electron conduction in the cathode material and provides a conductive matrix for the electrodeposition of Mn²⁺, which contribute to the performance of aqueous ZIBs.