Biomass-Derived Catalytically Active Carbon Materials for the Air Electrode of Zn-Air Batteries

Given the growing environmental and energy problems, developing clean, renewable electrochemical energy storage devices is of great interest. Zn-air batteries (ZABs) have broad prospects in energy storage because of their high specific capacity and environmental friendliness. The unavailability of cheap air electrode materials and effective and stable oxygen electrocatalysts to catalyze air electrodes are main barriers to large-scale implementation of ZABs. Due to the abundant biomass resources, self-doped heteroatoms, and unique pore structure, biomass-derived catalytically active carbon materials (CACs) have great potential to prepare carbon-based catalysts and porous electrodes with excellent performance for ZABs. This paper reviews the research progress of biomass-derived CACs applied to ZABs air electrodes. Specifically, the principle of ZABs and the source and preparation method of biomass-derived CACs are introduced. To prepare efficient biomass-based oxygen electrocatalysts, heteroatom doping and metal modification were introduced to improve the efficiency and stability of carbon materials. Finally, the effects of electron transfer number and H₂O₂ yield in ORR on the performance of ZABs were evaluated. This review aims to deepen the understanding of the advantages and challenges of biomass-derived CACs in the air electrodes of ZABs, promote more comprehensive research on biomass resources, and accelerate the commercial application of ZABs.