Facile fabrication and structure control of SiO2/carbon via in situ doping from liquefied bio-based sawdust for supercapacitor applications

Porous SiO2-Carbon composites with excellent electrochemical performance were fabricated from liquefied biobased sawdust via a simple in situ doping approach. Morphologies and pore textures of the samples were controlled effectively by doping with SiO2 and optimizing carbonization temperature. The morphologies of SiO2 Carbon composites from carbonization between 700-900 degrees C changed from bump-like to coral-like, to a network-like structure, and the pore textures changed from a disordered to an ordered structure. Benefitting from specific morphologies and pore textures, the large specific surface areas (538-780 m(2)/g) of the SiO2-Carbon composites exhibited excellent electrochemical performance for supercapacitors. Remarkably, the reticular-like SiO2-Carbon composites with an ordered porous structure at carbonization 900 degrees C revealed a high specific capacitance (260 F/g), energy density (23.1 wh/kg) and power density (640 w/kg) at a current density of 1.6 A/g in 1 M KOH electrolyte, as well as a good rate performance and stability (with capacitance retention above 97 % after 5000 cycles). Especially, the capacitance is around 1.4 times and 1.3 times higher than that of the undoped carbon and SiO2-Carbon carbonized at 700 degrees C, respectively. The results indicate that SiO2-Carbon composites should be a promising candidate for capacitive application, and the excellent capacitance is attributed to the contribution of pseudo-capacitance from the SiO2 doping and double layer capacitance from the special pore textures. This work provides a simple way for full utilization of biomass waste for supercapacitor material.