Biomorphic porous carbon derived from reed with enriched oxygen-functional groups for high-performance supercapacitors

Abstract

Biomass derived porous carbons have been widely used as remarkable supercapacitor electrodes. To investigate the effects of biomass pretreatment on structures and properties of derived porous carbons, we proposed baking-mediated carbonization method firstly and prepared reed-derived oxygen-doped porous carbons. The baking pretreatment is proved to protect the oxygen functional groups from escaping in the reed-derived porous carbons. The resultant OPC800-B2 bio‑carbon shows a large Brunauer-Emmett-Teller (BET) surface area of 1650 m2·g−1, especially with abundant oxygen functional groups of 9.63 at.%, which can promote the ion transportation and enhance the capacitive performance. As supercapacitor electrode, OPC800-B2 exhibits a specific capacitance of up to 336.4 F·g−1 at 1 A·g−1, greatly higher than that of OPC800 without using baking pretreatment. The symmetric two-electrode device assembled with OPC800-B2 in sodium sulfate (Na2SO4) electrolyte affords a superb energy density of 18.66 Wh·kg−1 at a power density of 450 W·kg−1. An excellent cycling stability of 93 % is also observed after 10,000 cycles. The outstanding electrochemical behaviors are attributed to the microporous features with sufficient oxygen-active functional groups caused by baking-mediated preparation engineering. This simple and non-polluting approach provides a feasible and cost-effective way to synthesize the functional biomass-derived porous carbons for energy applications.