Optimized Proton Assistance of Ni-Intercalated Bilayer Vanadate Cathode for High-Performance Aqueous Manganese...

Mn metal has become a highly promising candidate anode of aqueous batteries due to its high abundance, non-toxicity, relatively low redox potential, and large theoretical capacity. However, the development of Mn ion batteries (MIBs) is hindered by controversies over reaction mechanisms, metal hydrogen evolution reactions, and poor conversion efficiency. Therefore, a further comprehensive study is urgently desired for its research and application. In this work, a V₂O₅ bilayer structure is innovatively constructed by introducing stripping agents (H₂O and Ni²⁺) to form stable "Ni─O" columns, which not only enhances the stability of the structure but also effectively blocks interlayer corrosion. The preferential orientation and the excellent interlayer spacing d (001) = 10.28 Å broads Mn²⁺ diffusion channels. In this way, the sites for ion storage are also increased by creating abundant vacancies, accelerating the diffusion rate of ions in the modified V₂O₅ (Ni_0.48V₂O₅•0.90H₂O, NiVO) lattice. The co-storage mechanism of Mn²⁺/H⁺ ions effectively alleviates the limitations of high charge density and large solvation ion radius. Furthermore, the storage mechanism and structural evolution process are investigated via analytical chemistry. These findings provide new ideas for designing new positive electrode materials and effectively promote the progress of the MIB research and application.