Designing synthesis of porous biomass carbon from wheat straw and the functionalizing application in flexible, all-solid-state supercapacitors

Porous biomass carbon materials were successfully synthesized from wheat straw by a citric-acid-crosslinking and KOH-activating method. Structural characterization results indicate that the as-obtained biomass carbon materials have hierarchical porous structure and high specific surface area. Electrochemical test demonstrates that the porous biomass carbon materials from wheat straw have the optimal super-capacitive properties when the quality of KOH is 5 times that of the carbonization product, i.e.: high specific capacitance of 294 F g−1, superior rate performances of 200 F g−1 at 10 A g−1 and excellent cycle stabilization (97.6% of capacitance retention after 5000 cycles). More importantly, porous biomass carbon from wheat straw with the optimal performance was assembled into flexible, all-solid-state, symmetric supercapacitors. The assembled symmetric supercapacitors reveal high energy density (14 Wh kg−1 at 440 W kg−1 power density) and excellent cycle stability (only 4.3% capacitance loss after 8000 cycles). Meanwhile, the present full-cell supercapacitors manifest the remarkable flexibility, low-temperature resistance, and commercial value. Hence one can see that all-solid-state supercapacitors based on porous biomass carbon derived from wheat straw have great potential prospect in the field of portable and wearable electronic devices.