SYNTHESIS OF GRAPHENE FIBERS FOR USE IN SUPERCAPACITORS
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Date
2015-09-28
Authors
Lathankan, Rasenthiram
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Publisher
University of Waterloo
Abstract
Graphene a recently discovered form of carbon that has become an important material in the world of electrochemical storage due to a number of intriguing properties. Graphene exists in many different forms in different dimensionalities such as graphene foams and graphene paper. However in the 1 dimension graphene has only been recently explored in the form of graphene fibers. Graphene fibers are a cost effective, mechanically flexible, highly shapeable fiber that employs the properties of graphene. Wet spinning can be used to synthesize graphene oxide (GO) fiber, which is later then converted in graphene fibers (rGO) via chemical reduction. This project found that using large flake graphene oxide of concentration greater than 8mg/mL, a syringe needle size of 150 μm, a pump rate of 0.5-1 mL/min, a coagulation bath of 5% NaOH/Methanol will produce robust graphene oxide fibers. Capacitance of graphene fiber can be as high as 2000 mF/cm3. In order to further improve the strength of graphene fibers the wet spinning method was modified with a coaxial spinneret to add another polymer to coagulate along with graphene oxide. Chitosan was added to the coaxial spinneret to produce a chitosan-core graphene oxide fiber. It successfully produced long strands of chitosan-core graphene fibers up to about 1 meter in length. Chitosan core GFs were structurally improved compared to standalone graphene fiber, albeit it having a few discrepancies. The chitosan core was rendered a poor electrode for fiber-based supercapacitors.
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Keywords
supercapacitors, graphene, graphene fiber, supercapacitor, wet spinning, flexible supercapacitor