Oxygen Defects in β-MnO(2) Enabling High-Performance Rechargeable Aqueous Zinc/Manganese Dioxide Battery

Rechargeable aqueous Zn/manganese dioxide (Zn/MnO(2)) batteries are attractive energy storage technology owing to their merits of low cost, high safety, and environmental friendliness. However, the β-MnO(2) cathode is still plagued by the sluggish ion insertion kinetics due to the relatively narrow tunneled pathway. Furthermore, the energy storage mechanism is under debate as well. Here, β-MnO(2) cathode with enhanced ion insertion kinetics is introduced by the efficient oxygen defect engineering strategy. Density functional theory computations show that the β-MnO(2) host structure is more likely for H(+) insertion rather than Zn(2+), and the introduction of oxygen defects will facilitate the insertion of H(+) into β-MnO(2). This theoretical conjecture is confirmed by the capacity of 302 mA h g(−1) and capacity retention of 94% after 300 cycles in the assembled aqueous Zn/β-MnO(2) cell. These results highlight the potentials of defect engineering as a strategy of improving the electrochemical performance of β-MnO(2) in aqueous rechargeable batteries.