Sheet‐on‐Sheet Hierarchical Nanostructured C@MnO2 for Zn‐Air and Zn‐MnO2 Batteries

Abstract Sheet‐on‐sheet hierarchical composites, MnO 2 nanosheets on a microsheet of activated eggplant carbon (AEPC), are synthesized by reducing KMnO 4 in its aqueous solution in the presence of AEPC at room temperature followed by thermal annealing in air at 200 °C. This composite, namely AEPC@MnO 2 , shows enhanced catalytic activity towards oxygen reduction reaction in alkaline electrolyte with high durability. Zn‐air batteries using AEPC@MnO 2 as a catalyst in the cathode are found to deliver high discharge voltage and survive long‐term cycling. The sheet‐on‐sheet hierarchical composite with high surface area also equips Zn‐MnO 2 batteries with high capacity, high rate capability, high coulombic efficiency and decent cycling stability. The simple preparation and versatile functions make AEPC@MnO 2 a promising candidate for electrode materials for a range of practical applications.