Mechanically robust and highly compressible electrochemical supercapacitors from nitrogen-doped carbon aerogels

Abstract

Macroscopic, free-standing and flexible three dimensional porous carbon aerogel holds great potential for supercapacitor design but is often hindered by their inherent hydrophobicity, structure-derived fatigue failure and weak elasticity. In this study, a strong and flexible nitrogen-doped carbon aerogel is prepared by direct pyrolysis of bamboo cellulose nanofibers /melamine/graphene oxide hybrid aerogel, which features the characteristics of being catalyst-free, cost-effective and of small environmental footprint. The obtained monolithic carbon aerogel is constructed by welding amorphous carbon nanofibers and graphene nanoplatelets together into a hierarchical carbon-graphene architecture, demonstrating outstanding microstructure-derived resilience and mechanical strength. It is capable to undergo at least 40% reversible compressive deformation and the maximum compressive strength reaches 29.3 kPa. Impressively, due to the unique carbon-graphene architecture together with the hydrophilicity resulted from nitrogen-doping, the carbon aerogel exhibits an excellent specific capacitance of 225 F/g at a current density of 0.25 A/g as well as high energy and power densities of 31.25 Wh kg−1 and 12.9 kW kg−1, respectively. Furthermore, after 100 compression-release cycles, the fully recovered carbon aerogel still maintains great capacitive performances, indicating its superior mechanical durability and electrochemical stability.