Silk-Derived Highly Active Oxygen Electrocatalysts for Flexible and Rechargeable Zn-Air Batteries

Flexible and rechargeable Zn-air batteries, because of their high energy density, low cost, and environmental and human benignity, are one kind of the most attractive energy systems for future wearable electronics. The development of high-performance rechargeable Zn-air batteries depends on the synthesis of highly efficient and highly stable electrocatalysts for the oxygen reduction reaction/oxygen evolution reaction (ORR/OER). Herein, a silk-derived defect-rich and nitrogen-doped nanocarbon electrocatalyst [SilkNC/Ketjenblack (KB)] is reported. The SilkNC/KB is synthesized by pyrolyzing commercially available porous KB carbon impregnated with silk fibroin. It exhibits remarkable electrocatalytic activities and long-term stability for the ORR/OER, enabling its applications in high-performance liquid and solid rechargeable Zn-air batteries. Particularly, the all-solid-state Zn-air battery based on SilkNC/KB exhibits good flexibility and remarkable charge/discharge stability, enabling its promising applications in wearable and energy-efficient batteries.