Three-dimensional hierarchical porous carbon/graphene composites derived from graphene oxide-chitosan hydrogels for high performance supercapacitors

Graphene-based material, featured with high electrical conductivity, large surface area and good cycling performance, has been considered as one of the most promising materials for supercapacitor. In this work, three-dimensional hierarchical porous carbon/graphene composites (3DHCG) have been synthesized from lyophilized graphene oxide-chitosan (GO-CS) composite hydrogels by the combination of direct carbonization and chemical activation processes. The resulting graphene-based composite has been able to construct a hierarchical pore network with randomly opened macropores and micropores, facilitating fast diffusion to the interior surfaces during rapid charge/discharge process. When compared with the pure carbon, the synthesized 3DHCG composite exhibits remarkably enhanced specific capacitance of 320 F g(-1) at a current density of 1 A g(-1) in 6 M KOH solution, meanwhile maintaining excellent rate performance (with the capacity retention of 70% at 20 A/g) and outstanding cycling stability (96% retention after 2000 cycles). The improved electrochemical performances of graphenebased materials represent an alternative promising candidate for the application as supercapacitor electrodes. (C) 2015 Elsevier Ltd. All rights reserved.