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Aqueous batteries with high safety and cost efficiency usually employ metallic cations as charge carriers. Recently, ammonium (NH4+) ion batteries using the nonmetal NH4+ as a charge carrier exhibit distinct electrochemical features from conventional aqueous batteries. Herein, the electrochemical performances of a bimetallic hydroxide material are systematically studied with different charge carriers in the electrolytes, including NH4+, as well as the conventional monovalent metallic cations K+ and Na+, respectively. Electrochemical results indicate that the charge storage process using NH4+ as the working ions exhibits a higher discharge plateau, smaller electrochemical polarization, and larger discharge capacity than that using conventional metallic charge carriers. Experimental characterizations and theoretical calculations suggest that the strong interaction between NH4+ and the electrode material, as well as the low NH4+‐ion diffusion barrier lead to these superior electrochemical features. The assembled NH4+‐ion battery exhibits a good energy density of 123 Wh kg(cathode+anode)−1 at the power density of 480 W kg(cathode+anode)−1. These fundamental findings are important for developing good safety, low‐cost, and high‐energy aqueous batteries with sustainable NH4+ charge carriers. [ABSTRACT FROM AUTHOR]

Manganese (Mn) oxides are promising cathode materials for rechargeable aqueous Zn‐ion batteries. However, the Mn dissolution in weakly acidic electrolytes always hinders the development of better aqueous Zn–Mn batteries. Herein, a hydroxylated manganese oxide cathode material (H‐MnO2) is fabricated using an electrochemical method for stable aqueous Zn–Mn batteries without relying on the Mn2+ electrolyte additives. The partial hydroxylation of the oxides leads to charge redistribution of the material, changing the reaction thermodynamics and kinetics. Theoretical simulation suggests that the hydroxylation of manganese oxide promotes both Zn2+ adsorption thermodynamics and diffusion kinetics on the surface of H‐MnO2 but weakens the interaction between H+ and the electrode. Therefore, Zn2+ ions can be more reactive with the hydroxylated manganese oxide than H+ ions. Experimental results show that the Zn2+ insertion mechanism dominates the charge storage process of H‐MnO2, and the H+‐induced Mn dissolution reaction is effectively alleviated. Importantly, H‐MnO2 exhibits good cycling stability with 95% capacity retention over 5000 cycles at the current density of 3.8 A g−1 in the ZnSO4 electrolyte, outperforming the state‐of‐the‐art aqueous Zn–Mn batteries, even those with Mn2+ electrolyte additives. The findings provide new insights for designing stable manganese oxide cathodes in aqueous Zn–Mn batteries. [ABSTRACT FROM AUTHOR]