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Oriented Graphene Based Electrochemical Supercapacitor
preprintsubmitted on 28.01.2019, 10:15 and posted on 28.01.2019, 21:41 by Jingxiao Lyu, Mohannad Mayyas, Osama Salim, Dewei Chu, Rakesh Joshi
Graphene has attracted substantial interest as potential carbon electrode material for energy storage applications. Yet, the utility of this material for these applications is governed by its stability and microstructure (i.e., surface area and porosity). Graphene can be prepared in controlled orientation by changing the surface chemistry of GO flakes in suspensions via reduction which causes the graphene to coagulate and self-assemble in specific patterns. Tuning the structure and porosity of oriented graphene is possible by varying the synthesis conditions. Herein, we report the growth of oriented graphene from a relatively small flake size GO suspension. The prepared electrode material demonstrated an excellent electrochemical performance with a supercapacitance value of 195 F g-1 at 1 mV s-1 and low real impedance with good stability and integrity after 4000 cycles of continuous charge-discharge in 1 M KOH electrolyte. This excellent performance is due to the unique architecture of the oriented graphene which comprises micro-slits and meso-channels among the sheets. The meso-channels were suggested to allow rapid diffusion of charge carriers and ions while the micro-slits increase more surface area for electrochemical interactions per unit volume. The observations reported herein create a new understanding of the structure-stability-performance trade-off in oriented graphene and layout the foundation for further investigations on their sustainable utilization in energy storage applications.