‘Electron pump’ of homo-interface enhancing d/p-band center proximity for zinc storage

The progress of manganese-based materials as cathode materials for aqueous Zn-ion batteries (ZIBs) has encountered considerable challenges due to their inadequate conductivity and structural deformation during cycling. Herein, it is shown that by combining α-MnO₂ with δ-MnO₂ to construct an α-MnO₂@δ-MnO₂ homojunction, acting as “electron pump” to significantly improve electrical conductivity and ion transport dynamics, the electron transfer in homo-interface is accelerated. Meanwhile, the d/p-band center proximity is enhanced to adjust the ion adsorption energy to thermoneutral value, which promotes the kinetics of ion absorption and desorption, rapidly rejuvenating the electrochemically active surface area for subsequent adsorption and further enhancing the cyclic stability of the material. Consequently, the Zn/α-MnO₂@δ-MnO₂ battery exhibits one of the highest capacities of 402 mAh g⁻¹ at the current of 200 mA g⁻¹ and maintains capacity retention of 84 % over 1000 cycles at 1000 mA g⁻¹. This prominent electrochemical performance suggests that the homo-interface in MnO₂ may indicate the future advancement directions in advanced cathode materials for ZIBs.