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Aqueous rechargeable metal batteries have recently garnered considerable attention owing to their low cost, sufficient capacity, and the use of non‐flammable water‐based electrolytes. Among them, manganese batteries are particularly favored because of their stability, abundance, affordability, and high energy density. Despite their advantages, Mn storage host structures remain underexplored. Therefore, developing innovative host materials is crucial for advancing this field. In this paper, the study reports for the first time, the use of Ag0.33V2O5 as a cathode material in aqueous manganese batteries. The study explains the displacement/intercalation behavior of manganese and silver using electrochemical, structural, and spectroscopic analyses. Additionally, it is shown that cation (Ag+, Mn2+, H+) diffusion pathways can be simulated using diffusion‐barrier calculations. Finally, the study demonstrates high‐performance manganese batteries that exhibit a remarkable reversible capacity of ≈261.9 mAh g−1 at a current of 0.1 A g−1 and an excellent cycle retention of 69.1% after 2000 cycles at a current density of 1.5 A/g. The findings of this study contribute to the advancement of aqueous manganese battery technology, offering a promising pathway for developing safer, more cost‐effective, and high‐performance energy storage systems. [ABSTRACT FROM AUTHOR]

Magnesium batteries have attracted considerable attention as a promising technology for future energy storage because of their capability to undergo multiple charging reactions. However, most oxide materials utilized as hosts for magnesium batteries do not perform well at room temperature or in nonaqueous electrolytes. Herein, a host material, Na0.04MoO3·(H2O)0.49 is successfully developed through the chemical reduction of alpha‐MoO3, which enables magnesium storage reaction in a 0.5 m Mg(ClO4)2/acetonitrile electrolyte at 25 °C. Electrochemical analysis reveals that the cathode material possesses a discharge capacity of 157.4 mAh g−1 at a 0.2 C rate. The Na0.04MoO3·(H2O)0.49 cathode material also exhibits a capacity retention of 93.4% after 100 cycles compared to the first cycle at a 2 C rate, with an average discharge voltage of −0.474 V versus activated carbon (≈2.16 V estimated discharge voltage vs Mg/Mg2+). The study findings demonstrate, for the first time, the potential of this material as a cathode for magnesium batteries at ambient temperatures and in nonaqueous electrolytes. [ABSTRACT FROM AUTHOR]

Magnesium batteries have emerged as a promising alternative to lithium‐ion batteries due to their theoretical high energy density and abundant magnesium resources. Vanadium dioxide, VO2(B), has been reported as a high‐capacity cathode material for magnesium batteries. However, the electrochemical intercalation mechanism requires further elucidation due to a limited understanding of the structure‐property relationship. In this study, we re‐evaluated the magnesium storage capability of the material, with a particular focus on the influence of water content in nonaqueous electrolytes. The higher discharge capacity of 250 mAh g−1 is achieved exclusively in the wet electrolyte with 650 ppm water content. A significantly lower capacity of 51 mAh g−1 was observed in the dry electrolyte solution containing 40 ppm water content. Through X‐ray structural and elemental analyses, as well as magnesium‐ion diffusion pathway analysis using bond‐valence‐energy‐landscape calculations, the restricted capacity was clarified by examining the reaction mechanism. According to this study, the impressive capacity of magnesium‐ion battery cathodes may be exaggerated due to the involvement of non‐magnesium‐ion insertion unless the electrolytes′ water content is appropriately regulated. [ABSTRACT FROM AUTHOR]