▎ 摘　　要

Biomass-derived graphene-like material is a promising candidate for supercapacitor electrodes, while it is critical to controllably convert biomass into structure-tunable graphene. Herein, few-layer graphene-like biochar (FLGBS) was successfully fabricated from waste biomass in molten carbonate medium. Molten carbonate acted as the effective cat-alyst for graphitizing and the liquid medium for microcrystal relinking to achieve the rearrangement of carbon struc-ture. It was found that the stacking of graphene layer and formation of porous structure were influenced by the volume of reaction medium and biomass pre-carbonation. Namely, increasing the dosage of molten K2CO3 was in favor to form few layer-type graphene structure, but excess dosage could destroy the nanopore structure to expand the aperture. In addition, pre-carbonation at high temperature impeded the exfoliation of graphene layers. When FLGBSs were applied to fabricate conductive additive-free electrode, they displayed a superior supercapacitor performance (up to 237.4 F g-1 at 0.5 Ag-1). This excellent performance should be attributed to the large specific surface area, hierarchical pore structure and graphene-like structure. In short, this work could help to get insights into the structural evolution of biomass carbon to graphene-like biochar in molten carbonate medium and achieve the tailoring of microstructure for further application in energy storage.