Simultaneously tuning the hierarchical porous structure and graphitization degree of biomass derived carbon for supercapacitors

In this study, a series of biomass derived carbon with tunable hierachical porous structure and graphitization degree are prepared through biomass dehydration treatment combined with a one-step activation-graphitization process. Studies have shown that when the mass ratio of activator, graphitizing agent and dehydration precursor is 1:0.5:1, the derived carbon (GHPPC1-0.5) has an excellent hierarchical porous structure and a suitable graphitization degree. This unique microstructure brings it outstanding electrochemical performance, typically, the GHPPC1-0.5 possesses the superior specific capacitance (434 F g⁻¹) and rate performance (74% capacitance retention at 20 A g⁻¹) in three-electrode systems. The GHPPC1–0.5 based symmetric supercapacitors are assembled in aqueous electrolyte and organic electrolyte, respectively, and they both exhibit excellent energy density (28.8 and 70.5 Wh kg⁻¹) and acceptable cycling stability (7.8 and 14.4% loss over 5000 cycles). The above positive results herald the superiority of the biomass derived carbon preparation strategy proposed in this study.