Aqueous zinc-ion batteries (AZIBs) can benefit from a deep understanding of the electrochemical reaction mechanism of cathode materials, which can assist in resolving issues such as cathode dissolution and electrostatic interactions. We reported a straightforward two-step synthesis of polydopamine coated MnO2 (MnO2@PDA) and revealed the energy storage mechanisms in AZIBs. The layered structure of MnO2 creates a generous passage for the insertion of H+/Zn2+ ions. Simultaneously, the plethora of functional groups within PDA exerts a robust desolvation effect, bolstering the transfer rate of H+/Zn2+. This effect significantly enhances the overall efficiency and performance of cathode. The AZIBs, incorporating MnO2@PDA cathode material, consequently exhibit a satisfactory cycling capacity (412 mAh g−1 at 0.1 A g−1) and a superb specific energy (561.6 Wh kg−1 at 136.34 W kg−1). This work provides a new path for design strategies and catalytic mechanisms of MnO2@PDA cathode.