Zn/MnO2 Battery Chemistry With H+ and Zn2+ Coinsertion

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.