Three-dimensional porous graphene-like sheets synthesized from biocarbon via low-temperature graphitization for a supercapacitor

Biocarbons are difficult to graphitize even at 3000 degrees C. In this study, three-dimensional porous graphene-like sheets (3DPGLS) were directly synthesized from biocarbons at 900 degrees C. Potassium carbonate was utilized as a catalyst to release graphite microcrystals from the crosslinked sp(3) carbon atoms in the hard carbon phase, and subsequently recrystallized them to form graphene layers. The as-obtained 3DPGLS showed a high purity and low defect density, and possessed high conductivity (32.14 S cm(-1)) and specific surface area (1506.19 m(2) g(-1)). Without conductive additives, the capacitance of 3DPGLS reached 91.15 F g(-1) at a current density of 0.2 A g(-1) acting as a two-electrode symmetrical supercapacitor electrode material in an organic electrolyte. 85.1% of the initial capacitance was maintained after 5000 cycles at a current density of 0.1 A g(-1).