Bimetallic-ions co-intercalation to stabilize vanadium-oxygen bond towards high-performance aqueous zinc-ion storage

Aqueous zinc-ion batteries (AZIBs) have received increasing attention in large-scale energy storage systems because of their appealing features with respect to safety, cost, and scalability. Although vanadium oxides with different compositions demonstrate promising potential as the cathodes of AZIBs, the narrow interlayer spacing, inferior electronic conductivity, and high dissolution in electrolyte seriously restrict their practical applications. Here we design an ingenious bimetallic-ions (Mg2+ and Al3+) co-intercalation strategy to boost the AZIBs performances of V6O131.31H2O (VOH). The bimetallic-ions intercalation expands the interlayer spacing, increases the electronic conductivity, and more importantly stabilizes the vanadium-oxygen bond in VOH, which promotes the ion/electron transport kinetics and restrains the vanadium oxides dissolution. As expected, MgAl-VOH cathodes deliver ultrahigh specific capacities of 524.9 and 275.6 mAh g−1 at the current densities of 0.1 and 5 A g−1, respectively, comparable to the highest value in vanadium oxides. The underlying zinc-ion storage mechanism is unambiguously clarified with the aid of density function theory calculations and in-situ structure characterizations. This work opens up a new avenue for boosting AZIBs performances by designing bimetallic-ions co-intercalated cathodes.