Wood-Derived Integral Air Electrode for Enhanced Interfacial Electrocatalysis in Rechargeable Zinc-Air Battery.

ABSTRACT

Zinc-air batteries (ZABs) are promising as energy storage devices owing to their high energy density and the safety of electrolytes. Construction of abundant triple-phase boundary (TPB) effectively facilitates cathode reactions occurring at TPB. Herein, a wood-derived integral air electrode containing Co/CoO nanoparticles and nitrogen-doped carbonized wood (Co/CoO@NWC) is constructed with a dual catalytic function. The potential gap between oxygen reduction and evolution is shortened to 0.77 V. Liquid ZABs using Co/CoO@NWC as cathode exhibit high discharge specific capacity (800 mAh gZn-1 ), low charge-discharge gap (0.84 V), and long-term cycling stability (270 h). Co/CoO@NWC also shows distinguished catalytic activity and stability in all-solid-state ZABs. The inherent layered porous and pipe structures of wood are well maintained in catalytically active carbon. The different hydrophilicity of carbonized wood and Co/CoO endow abundant TPBs for battery reaction. The Co/CoO located on TPB provides main active sites for oxygen reactions. The inherent pipe structures of wood carbon and the interaction between Co/CoO and NWC effectively prevent nanoparticles from aggregation. The design and preparation of this monolithic electrocatalyst contribute to the broad-scale application of ZABs and promote the development of next-generation biomass-based storage devices.