High Mass Loading Potassium Ion Stabilized Manganese Dioxide Nanowire Forests for Rechargeable Zn Batteries

Manganese dioxide (MnO2) represents an ideal cathode material for rechargeable aqueous Zn batteries due to its high theoretical capacity (308 mAh g-1), suitable potential (1.4 V vs. Zn2+/Zn), natural abundance, and negligible toxicity. However, the capacity and rate capability of MnO2 deteriorate significantly in thick electrodes owing to its low electrical and ionic conductivities. Herein, we report the design of high mass loading potassium ion stabilized α-MnO2 (K0.133MnO2) nanowire forests on carbon cloth through a seed-assisted hydrothermal method for Zn batteries. The vertically aligned K0.133MnO2 nanowire forests with uninterrupted charge transport afford a high area capacity of 3.54 mAh cm-2 and a capacity retention of 79.2% over 1000 cycles in aqueous electrolyte. Moreover, the high area capacity and cyclability can be readily transferred to quasi-solid-state devices.