Engineering d-band center of Mn to strengthen Mn–O bonding for long cycle life zinc-ion battery

Abstract

MnO₂ has emerged as one of the favored cathode materials for aqueous zinc ion batteries (AZIBs) due to its high theoretical capacity and abundant crystalline structures. However, MnO₂ cathode generally suffers from poor electrical conductivity and rapid capacity degradation due to unavoidable manganese dissolution during cycling, limiting their further utilization. In this study, we modify the d-band center of Mn by introducing non-precious metal Bi atoms into the MnO₂ system, thereby strengthening the Mn–O bonding to inhibit manganese dissolution. Theoretical calculations reveal that the d-band center of Mn in Bi-MnO₂ shifts upward, promoting electron transfer from O 2p orbitals to Mn–O bonding orbitals. This enhances the Mn–O bond strength, stabilizing Mn atoms in the crystal lattice and reducing manganese solvation loss. As a result, the conductivity and cyclic stability of Bi-MnO₂ are significantly improved. The results demonstrate that Bi-MnO₂ exhibits outstanding electrochemical properties, with a capacity of 392.3 mAh g⁻¹ after 100 cycles at 0.2 A g⁻¹ and a capacity retention of 83.25% after 5000 cycles at 1.0 A g⁻¹. This study presents a new approach to address the manganese dissolution issue, which could further advance the application of d-band center theory in MnO₂ materials.