Ionic, Organic and Strong Electrolytes with Graphene on Metal Oxide Composite Electrodes for Supercapacitors

This paper reports a scalable prototype supercapacitor using metal oxides and graphene oxide and an ionic liquid electrolyte. Our novel approach to combining pseudocapacitance and electric double layer capacitance in a tri-layered composite electrode, promises to increase the energy density of the device, without sacrificing the high power density attributed to it. Solutions of KOH, acetonitrile and the ionic liquid 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMIm-BF4) are used in manufacturing our devices, with more focus on the ionic liquid. These room temperature molten salts are predicted to function better as an electrolyte under extremely low temperatures. This paper presents the scalable synthesis of composites of reduced graphene oxide (rGO) on MnO2 nanowires and Co3O4 nanorods. We employ a modified electrophoretic deposition process which produces uniform layers of rGO on our metal oxide enhanced electrodes. The capacitor devices are assembled in a sandwich style which closely resembles commercial electric double layer capacitor (EDLC) devices.