Graphene Oxide Self-Assembled with a Cationic Fullerene for High Performance Supercapacitor Applications

Abstract

Supercapacitors, with promising high power densities and long cycle life, have attracted considerable attention due to their widespread applications in electric vehicles and high power appliances. Currently, carbon based porous materials such as activated carbon, activated carbon fibers, carbon aerogels, graphene, etc., are popularly used as electrode materials for supercapacitor applications. Graphene oxide (GO), an intermediate in the graphene synthesis from graphite, laden with oxygen functionalities behaves much like the quinone/hydroquinone redox switching process and has been exploited as a pseudocapacitor. However, the inevitable partial stacking occurring in GO, reduce surface area exposure to the electrolyte, thus substantially affecting the pseudocapacitive response. In the present work, we present a new strategy to prepare a cationic fullerene (CFU) intercalated graphene oxide (GO-CFU) composite. In an aqueous solution, positively charged CFU was electrostatically aligned with oppositely charged GO. The CFU behaving as a spacer between GO layers, suppress the GO stacking and expose basal plane oxygen functionalities with electrolyte more effectively. XRD analysis of GO-CFU shows that the (001) and (002) plane of GO is shifted negatively (by 2q of 1 and 1.2o, respectively) which validates the intercalation of CFU into GO layers. The prepared composite was subjected to supercapacitor performance evaluation studies. It was found that specific capacitance of the composite reached 357 F g-1 at 0.4 A g-1 current density in 1 M H2SO4. During 5000 charge/discharge cycles at 5 A g-1, the capacitance of the GO-CFU composite increases slightly (4% increase in GO-CFU vs. 4% decrease in GO), which validates the effectiveness of a self-assembly strategy for high performance supercapacitor applications.