Highly crystalline ramsdellite as a cathode material for near-neutral aqueous MnO2/Zn batteries

Abstract

Chemically-prepared MnO₂ containing a highly crystalline ramsdellite phase was tested as a cathode material in aqueous Zn-salt (ZnSO₄ and Zn(CF₃SO₃)₂) based electrolytes for the first time. This aqueous MnO₂/Zn cell has shown excellent performance and reversibility, retaining ≈65% of its initial capacity for more than 1000 cycles. The charge storage mechanism is complex and includes a ramsdellite/tetragonal spinel two-phase reaction.