基于木质素磺酸盐衍生石墨烯量子点/石墨烯水凝胶的柔性超级电容器电极

Abstract

The emerging flexible supercapacitor has drawn great attentions, challenges still exist in the search for renewable, stable electrode materials. In this work, biomass lignosulfonates (LS) from waste liquor of sulfite pulping were used to produce graphene quantum dots (GQDs) by a two-step method. The LS-derived GQDs were synthesized with a large number of N, S, O-containing functional groups, which can participate in Faradaic reactions to provide improved pseudo capacitance and enhance structure stability of the supercapacitor electrode. Thus, the functionalized GQDs were used to decorated graphene hydrogels (GH-GQD). As expected, the prepared flexible GH-GQD electrode has excellent electrochemical performance and stability. It exhibits an impressive specific capacitance of 452 F g-1 at a current density of 0.5 A g-1, which is nearly double than that of pure GH (231 F g-1). Moreover, the GH-GQD electrode has a high cycle stability (89.0% capacitance retention after 10000 charge/discharge cycles) and mechanical flexibility (93.3% capacitance retention when bent to 180°). This study broadens the high-valued utilization of biomass waste and provides new ideas for the development of renewable and environment-friendly flexible energy storage devices.