Ionic and Electronic Conductivity of Graphene Oxide Thin Films and Flowable Suspensions for Electrochemical Flow Capacitors and Redox Flow Batteries

Graphene oxide in aqueous suspension has multiple promising applications as novel nanocomposite electrodes in free-standing film and flowable electrodes for energy storage applications such as redox flow batteries. From the nanomaterial level, interactions between suspended aqueous graphene oxide particles can be used to assemble thin film electrodes or as flowable particle suspension electrodes. Using layer-by-layer self-assembly, 3D electrodes of graphene oxide films are created from all solution based aqueous spin coating techniques. Noble metal salt solutions were spin coated in between sequential graphene oxide layers. The electrostatic interaction of the noble metal complexes and the oxygenated functional groups at the edge and basal plane on graphene oxide help control 3D spacing of graphene films preventing aggregation from self-stacking and loss of surface area. This platform synthesis procedure can be utilized to produce scalable free-standing film graphene oxide electrodes with controlled 3D spacing and with enhanced conductivity from the presence of the noble metals. In addition to free-standing film electrodes, graphene oxide suspensions were electrochemically characterized at different particle loadings as flowable electrodes. Materials characterization techniques such as Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) are used to study the particle size, morphology, and surface elemental composition. Electrochemical techniques such as impedance spectroscopy and cyclic voltammetry are used to study electronic and ionic conductivity and electrochemical surface area. Both the SEM imaging and electrochemical testing confirmed the fabrication of thin films with similar resistivity and conductivity to industry produced chemical vapor deposition films. The free-standing graphene oxide-noble metal cluster thin films were characterized for their potential application as stationary porous electrodes used in electrochemical flow capacitors or batteries. In addition to free-standing film testing, analysis of EIS plots for aqueous graphene oxide solutions demonstrates the potential for suspensions as flowable electrodes. These diverse applications in static and flow from aqueous graphene oxide suspensions show promising application before integration as electrodes into energy storage applications such as flow batteries and flow capacitors.

^*Contact: Dr. Enoch Nagelli, Email: enoch.nagelli@westpoint.edu