Dual-Site Mn-Doped Vanadate Cathodes Involving Vanadium and Manganese Dual Redox Chemistry for High-Energy Aqueous Zinc-Ion Batteries

Popular vanadium-oxide and manganese-oxide based cathodes have garnered considerable attention for aqueous zinc-ion batteries (AZIBs) by virtue of their high discharge capacity and high working voltage, respectively. However, the low operating voltage of vanadium-oxide//Zn batteries and low specific capacity of manganese-oxide//Zn batteries significantly limit their practical applications. Herein, the V and Mn redox reactions are simultaneously activated in an intra-/interlayer dual-site Mn-doped Mn0.4V1.7O5·0.5H2O (MnVO) material to enhance the energy density. Specifically, the intralayer Mn-ions serve as redox centers to contribute capacity in the high-voltage region, while the interlayer Mn-ions mainly act as "pillars" to strengthen the layered structure. The combined spectroscopic/imaging analyses and theoretical computations elucidate the reversible V and Mn redox chemistry accompanied by H+/Zn2+ coinsertion/extraction in MnVO. Consequently, the tailored MnVO cathode achieves a significantly enhanced energy density (1.83 and 1.42 times those of vanadium-oxide and manganese-oxide, respectively) and an ultralong cycling durability (10000 cycles) in AZIBs.