A high specific capacity aqueous zinc-manganese battery with a ε-MnO2 cathode

Aqueous zinc-manganese dioxide batteries (Zn-MnO2) are gaining considerable research attention for energy storage taking advantages of their low cost and high safety. Polymorphic MnO2 (α, β, γ, δ, λ, and amorphous) has been extensively studied, but reports of akhtenskite MnO2 (e-MnO2) are limited and the performance of e-MnO2-based ZIBs existing is not very excellent. Here, e-MnO2 was synthesized and applied to the cathode material of Zn-ion batteries. It exhibits a high specific capacity of 465 mAh g−1 at 0.2 C, high energy density (620 Wh kg−1) and excellent cycle stability (the capacity increases from 312 to 435 mAh g−1 after 150 cycles at 1 C). Its good electrochemical performance laid a solid foundation for its further research and large-scale use in zinc-ion batteries.