AQUEOUS BASED EXFOLIATION OF GRAPHENIC MICROSHEETS VIA BATCH AND CONTINUOUS COUETTE FLOW REACTORS
The next generation of energy storage devices must be capable of keeping up with the demand for high capacity and high performance, while minimizing their cost and environmental impact. Current global trends look towards the utility of such devices for electric vehicles, zero/low carbon energy sources and computational power. Graphene has risen to prominence, since its discovery in 2004, as a super material with superior electrical, mechanical, thermal and optical properties. This has led to its utilization of graphene in a variety of industries such as automotive manufacturing to semiconductors. A variety of methods for manufacturing graphene have been developed from bottom-up methods such as chemical vapor deposition to top-down methods such as mechanical exfoliation. However, these methods are limited in their ability to scale and produce high quality graphene, especially with low cost. Liquid phase exfoliation can be utilized as a means of effectively exfoliating high quality graphene in a scalable manner at relatively low cost. Taylor-Couette reactor systems consist of concentric cylinders with a fluid in the gap between them and a combination of inner and outer cylinder co and counter rotation. Graphene exfoliation via Taylor-Couette reactor systems is able to produce highly exfoliated and high-quality graphene via the high shear rates it produces in a localized gap.In this work we investigate the use of an outer cylinder rotating Taylor-Couette reactor system for graphene exfoliation in an aqueous environment. First, we examine the nature of curvature effects in the gap on the production of expanded graphite and few layer graphene (FLG). This resulted in effective expansion of graphite and exfoliation into FLG at thin gap conditions utilizing high shear rates in a laminar flow regime. Then we demonstrate the ability to exfoliate graphene in a continuous manner at high production rates and scalability of this process, while showing the efficacy of our exfoliated graphene in Li-Ion batteries and their ability to outperform commercial graphene. Finally, we explore the use of synthetic, natural and recycled graphite precursors in our exfoliation process explore the nature of graphene fiber composites and their novel thermos-responsive conductivity behavior.