Supercapacitors have the potential to replace Li ion batteries as the next-generation electrical energy storage technology in demanding applications due to their high power density and excellent cycling stability. Graphene-based supercapacitor electrodes are very attractive because they feature high surface area, high electrical conductivity, and chemical inertness; however their capacitance is limited by their low density of states at the Fermi level (ca. 1 e^- per 100 C atoms). To overcome the current charge storage limitations of graphene-based supercapacitors, researchers at Lawrence Livermore National Laboratory have developed an all-carbon composite graphene/fullerene supercapacitor combining the high charge storage capacitance of fullerenes (up to 6 e^- per C₆₀) with the high electrical conductivity of 3D mesoporous graphene macro-assemblies (GMAs) (Figure 1).

Fig. 1: Fullerene-grafted 3D graphene bulk material.

Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant 17-ERD-017. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. IM Release Number LLNL-ABS-741683.