Renewable biomass-derived carbons for electrochemical capacitor applications

Biomass is rich,renewable,sustainable,and green resources,thereby excellent raw material for the fabrication of carbon materials.The diversity in structure and morphology of biomass are relevant in obtaining carbon materials with dif-ferent structures and performances.The inherent ordered porous structure of biomass also benefits the activation process to yield porous carbons with ultra-high specific surface area and pore volume.Besides,obtained biomass-derived carbons(BDCs)are hard carbon with porous morphology,stable structure,supe-rior hardness/strength,and good cycling performances when used in electro-chemical capacitors(ECs).The inherent N,S,P,and O elements in biomass yield naturally self-doped N,S,P,and O BDCs with unique intrinsic structures.In this paper,the synthesis approaches and applications of BDCs in ECs are reviewed.It shows that BDCs electrochemical performances are highly determined by their pore structures,specific surface areas,heteroatoms doping,graphitization degree,defects,and morphologies.The electrochemical performances of BDCs can further be improved by compositing with other materials,such as graphene,carbon nanofibers/nanotubes,transition metal oxides or hydroxides,and con-ducting polymers.The future challenges and outlooks of BDCs are also provided.