Hydrated ammonium manganese phosphates by electrochemically induced manganese-defect as cathode material for aqueous zinc ion batteries

Aqueous zinc ion batteries (AZIBs) with the merits of low cost, low toxicity, high safety, environmen-tal benignity as well as multi-valence properties as the large-scale energy storage devices demonstrate tremendous application prospect. However, the explorations for the most competitive manganese-based cathode materials of AZIBs have been mainly limited to some known manganese oxides. Herein, we re-port a new type of cathode material NH4MnPO4middotH2O (abbreviated as AMPH) for rechargeable AZIBs syn-thesized through a simple hydrothermal method. An in-situ electrochemical strategy inducing Mn-defect has been used to unlock the electrochemical activity of AMPH through the initial charge process, which can convert poor electrochemical characteristic of AMPH towards Zn2 + and NH4 + into great electrochem-ically active cathode for AZIBs. It still delivers a reversible discharge capacity up to 90.0 mAh/g at 0.5 A/g even after 10 0 0th cycles, which indicates a considerable capacity and an impressive cycle stability. Fur-thermore, this cathode reveals an (de)insertion mechanism of Zn2 + and NH4 + without structural collapse during the charge/discharge process. The work not only supplements a new member for the family of manganese-based compound for AZIBs, but also provides a potential direction for developing novel cath-ode material for AZIBs by introducing defect chemistry.(c) 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.