Partially reduced graphite oxide as an electrode material for electrochemical double-layer capacitors.

Partially reduced graphite oxide was prepared from graphite oxide by using synthetic graphite as precursor. The reduction of graphite oxide with a layer distance of 0.57 nm resulted in a reduction of the layer distance depending on the degree of reduction. Simultaneously the amount of oxygen functionalities in the graphite oxide was reduced, which was corroborated by elemental analysis and EDX. The electrochemical activation of the partially reduced graphite oxide was investigated for tetraethylammonium tetrafluoroborate in acetonitrile and in propylene carbonate. The activation potential depends significantly on the degree of reduction, that is, on the graphene-layer distance and on the solvent used. The activation potential decreased with increasing layer distance for both positive and negative activation. The resulting capacitance after activation was found to be affected by the layer distance, the oxygen functionalities and the used electrolyte. For a layer distance of 0.43 nm and with acetonitrile as the solvent, a differential capacitance of 220 Fg(-1) was achieved for the discharge of the positive electrode near the open-circuit potential and 195 Fg(-1) in a symmetric full-cell assembly.