Formation of hierarchical 3D cross-linked porous carbon with small addition of graphene for supercapacitors

In the present paper, starch was used as raw material to prepare carbon material with low-temperature hydrothermal route and hierarchical three-dimensional cross-linked porous carbon was successfully synthesized with the help of a small amount of graphene for high-performance supercapacitors. It's found that presence of graphene is a crucial condition for the formation of 3D porous carbon and graphene acts as a skeleton in the porous carbon. This kind of carbon material exhibited very high surface area of 1887.8 m(2) g(-1) and delivered excellent electrochemical performance. Its specific capacitance can reach 141 F g(-1) at 0.5 A g(-1) and more importantly, after 10,000 cycles 98.6% of initial specific capacitance can be maintained. To explore the practical application of the 3D porous carbon, an asymmetric supercapacitor coin-type device was assembled with 3D porous carbon and graphene as electrode materials in organic electrolyte. The constructed device exhibited high energy density of 48.5 Wh.kg(-1) at a power density of 1.5 kW kg(-1) and still maintains 39.625 Wh.kg(-1) under the high power density (15 kW kg(-1)). These results will promote the rapid development of 3D porous carbon prepared by low-temperature route and the application in supercapacitors. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.