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

Sheet-on-sheet hierarchical composites, MnO2 nanosheets on a microsheet of activated eggplant carbon ( AEPC), are synthesized by reducing KMnO4 in its aqueous solution in the presence of AEPC at room temperature followed by thermal annealing in air at 200 degrees C. This composite, namely AEPC@MnO2, shows enhanced catalytic activity towards oxygen reduction reaction in alkaline electrolyte with high durability. Zn-air batteries using AEPC@ MnO2 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-MnO2 batteries with high capacity, high rate capability, high coulombic efficiency and decent cycling stability. The simple preparation and versatile functions make AEPC@MnO2 a promising candidate for electrode materials for a range of practical applications.