Molten salt synthesis of hierarchical porous carbon from wood sawdust for supercapacitors

Molten salt synthesis is applied in the preparation of porous carbon under air atmosphere. Wood sawdust is used as the carbon source, and the molten salt containing KCl and KOH acts as structure-directing agent to tailor microstructure of porous carbon, making the resulting carbon have improved electrochemical performance. The function of molten salt is controlled by the cooperation of KCl and KOH in different compounding ratios. Benefiting from the open pore structure, the optimized carbon (CS-H3) shows the highest specific capacitance of 286 F g−1 in 1 A g−1, and the energy density reaches 5.63 W h kg−1 at a power density of 9213 W kg−1 in 6 M KOH. Furthermore, CS-H3 also displays an excellent cycle life of high capacitance retention of 99.8% after 10,000 cycles. This work provides a high-efficiency route to prepare hierarchical porous carbon from biomass, showing a promise in the industrial production.