Inducing preferential intercalation of Zn2+ in MnO2 with abundant oxygen defects for high-performance aqueous zinc-ion batteries

Unfavorable proton intercalation leading to the generation and shedding of side reaction products is still a major challenge for the performance of manganese-based aqueous zinc-ion batteries (AZIBs). In this study, we present a porous oxygen-deficient MnO2 (Od-MnO2) synthesized through n-butyllithium reduction treatment to induce preferential Zn2+ intercalation, thereby effectively mitigating the adverse consequences of proton intercalation for high-performance AZIBs. Remarkably, Od-MnO2 as a cathode material for AZIBs exhibits a specific capacity of 341 mA h g-1 at 0.1 A g-1 and 139 mA h g-1 at 5 A g-1, and outstanding long-term stability with a capacity retention of 85.4% for over 1200 cycles at 1 A g-1. Moreover, the Zn/Od-MnO2 pouch cell displays decent durability with a capacity retention of similar to 90% for over 200 cycles at 1C. Our study opens new opportunities for the rational design of high-performance cathode materials by regulating the electronic structure and optimizing the energy storage process for rechargeable AZIBs.