118 / 2021-11-10 20:37:58

3D Conductive Cellulose Nanofiber Carbon Aerogels with the Desired Pores for Supercapacitors

cellulose nanofiber; conductive carbon aerogels; hierarchical pores; supercapacitors

Carbon aerogel has the advantages of good chemical stability of carbon material, high electrical conductivity and adjustable pores, specific surface area of carbon aerogel, making it an excellent matrix material. However, due to the limitation of its microscopic structure, carbon aerogel as electrodes still have problems with low capacitance ratio, poor cyclic stability and so on. In this work, cellulose nanofiber was chose as raw material, which was mixed with oxidation graphene and ZIF 67 in water to directional freeze drying in liquid nitrogen. Next, cellulose nanofiber based porous carbon aerogel was obtained by carbonization at high temperature. The high temperature reduction of graphene increased the conductivity of the material, as well as the carbonization of ZIF67 in the high temperature formed N-doped Co nano-graphite carbon. In addition, the Co metal catalyzed the graphene sheet to form nano-molecular sieve so as to form hierarchical porous 3D conductive carbon aerogel, which not only has a high specific surface area, but also form hierarchical pores. The cellulose nanofiber-based porous carbon composite aerogel has the high specific capacitance of 294.7 F g-1 when the current density is 1 A g^-1. More notably, symmetric supercapacitors composed with cellulose nanofiber -based porous carbon aerogel has an excellent specific capacitance of 84.3 F g^-1 at A current density of 0.5 A g^-1, high energy density of 10.1Wh kg^-1 and outstanding power density of 180W kg^-1. What's more, the capacitive retention rate can reach 82% after 10000 charge-discharge cycles. In this work, the preparation method of cellulose nanofiber-based carbon aerogel provides a new idea for the application of cellulosic biomass materials in the field of new energy.