Zn/MnO_2 Battery Chemistry with H~+ and Zn~(2+) Coinsertion

摘要

Rechargeable aqueous Zn/MnO_2 battery chemistry in a neutral or mildly acidic electrolyte has attracted extensive attention recently because all the components (anode, cathode, and electrolyte) in a Zn/MnO_2 battery are safe, abundant, and sustainable. However, the reaction mechanism of the MnO_2 cathode remains a topic of discussion. Herein, we design a highly reversible aqueous Zn/MnO_2 battery where the binder-free MnO_2 cathode was fabricated by in situ electrodeposition of MnO_2 on carbon fiber paper in mild acidic ZnSO_4+MnSO_4 electrolyte. Electrochemical and structural analysis identify that the MnO_2 cathode experience a consequent H~+ and Zn~(2+) insertion/extraction process with high reversibility and cycling stability. To our best knowledge, it is the first report on rechargeable aqueous batteries with a consequent ion-insertion reaction mechanism.