Graphene-doped carbon xerogel combining high electrical conductivity and surface area for optimized aqueous supercapacitors

A graphene doped carbon xerogel was synthesized by simply replacing the water (solvent) by an aqueous well-dispersed graphene oxide stable suspension in the precursor mixture used for the synthesis of the organic xerogel. During the carbonization of the organic xerogel, the graphene oxide sheets are reduced to graphene, which is embedded and well dispersed within the carbon xerogel matrix. Only a small minimum amount of graphene oxide is necessary to interconnect the graphene sheets throughout the carbon xerogel. This material has both a high porosity and an excellent electrical conductivity so that, when used as electrode in aqueous supercapacitors at high current density, it provides them with 25% more capacitance and 100% more power than the undoped carbon xerogels. The synthesis conditions, characteristics of the carbons and how these affect the electrical conductivity and performance of the materials in the supercapacitors are discussed.The authors gratefully acknowledge the financial support of the Ministerio de Economía y Competitividad of Spain, MINECO (Project CTQ2014-54772-P) and CTQ2013-44213-R), and Generalitat Valenciana for project PROMETEOII/2014/007)