Strengthening the Mn–O–Mn Bonds for Durable Aqueous Zinc‐Manganese Batteries

Manganese dioxide (MnO 2 ) is a promising cathode material for aqueous zinc‐manganese batteries (AZMBs) due to its high capacity and low cost. However, MnO 2 suffers from the manganese dissolution during the charge‐discharge process which leads to structural instability and poor durability of AZMBs. In this work, we propose a strategy of strengthening the Mn–O–Mn bonds to improve the cycling stability of AZMBs through doping five elements (Fe, Co, Ni, Cu, Zn) into δ‐MnO 2 to fabricate Mn 0.9 Fe 0.02 Co 0.02 Ni 0.02 Cu 0.02 Zn 0.02 O 2 (5‐ME‐MnO 2 ) as the cathode material. Specifically, Cu enhances the structural stability of MnO 2 by its higher charge density, effectively preventing the collapse of the layered framework. Meanwhile, Fe, Co, and Ni significantly accelerate ion diffusion and promote electrochemical activity, and the predoping of Zn lowers the energy barrier for Zn 2+ insertion and extraction. This strengthened bond framework effectively suppresses manganese dissolution, resulting in remarkable electrochemical performance: a high capacity of 372 mAh g −1 at 0.1 A g −1 , excellent rate capability (119 mAh g −1 at 10 A g −1 ), and outstanding cycling stability with 85.7% capacity retention after 1500 cycles. This facile and efficient strategy developed in this work can be extended to design high‐performance cathode materials for other energy storage devices.