Proton-Assisted Aqueous Manganese-Ion Battery Chemistry

Aqueous manganese-ion batteries (MIBs) are promising energy storage systems because of the distinctive merits of Mn metal, in terms of high abundance, low cost, nontoxicity, high theoretical capacity and low redox potential. Conventional MIBs are based on the Mn²⁺ ion storage mechanism, whereas the capacity in cathode materials is generally limited due to the high charge density and large solvated ionic radius of Mn²⁺ ions in aqueous electrolytes. Herein, proton intercalation chemistry is introduced in aqueous MIBs, in which the layered Al_0.1 V₂ O₅ ⋅1.5 H₂ O (AlVO) cathode exhibits a consequent Mn²⁺ and H⁺ ion intercalation/extraction process. Such an energy storage mechanism contributes to enhanced electrochemical performance, including high capacity, fast reaction kinetics and stable cycling behavior. Benefiting from this proton intercalation chemistry, the aqueous Mn||AlVO cells could deliver high specific energy and power simultaneously. This work provides a route for the design of high-performance aqueous MIBs.