Scalable Manufacturing of Graphene Nanocomposites for Electronic Devices

Downing, Julia Rocio

doi:https://doi.org/10.21985/n2-1894-yk62

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Scalable Manufacturing of Graphene Nanocomposites for Electronic Devices

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Nanomaterials present an exciting landscape of innovation at length scales below 100 nm, wherein controllable synthesis and materials metrology have led to tunable structure-property relationships and next-generation products. The disruptive field of nanotechnology is poised to capitalize upon the exotic chemistry and physics of these nanomaterials to enable more efficient energy storage and conversion, advanced sensors, faster computation, and life-saving medical treatments. Since 2004, graphene has upended the field of materials science as the first two-dimensional nanomaterial to be discovered. Owing to its mechanical robustness, high electrical conductivity, and processability, it is broadly applicable to many consumer electronics including batteries, sensors, photovoltaics, conductive coatings, and structural composites. However, graphene has yet to be commercialized successfully owing to poor quality control on the industrial scale, energy-intensive synthesis and processing, and high specific production cost. To this end, this thesis centers around scalable manufacturing of graphene while maintaining high quality, low defect density, and optimal performance in downstream for electronic devices. By leveraging methodologies from materials science, chemical and process engineering, mechanical engineering and beyond, this thesis augments gram-scale production of graphene nanocomposites that are shown to be highly versatile and compatible with a plethora of energy storage devices and additively manufactured electronics. Automation of a continuous-flow shear-mixing process enables unprecedented high-volume production of a liquid-phase exfoliated graphene and ethyl cellulose nanocomposite. Subsequently, a major bottleneck in post-synthetic separation of shear-mixed graphene is addressed with the adaptation of cross-flow filtration (CFF), an entirely flow-based alternative to dead-end processing techniques, to the graphene and ethyl cellulose system. Major improvements to specific production costs and environmental impacts of graphene production using CFF are validated through life cycle analysis and technoeconomic analysis, leading to highly conductive, printed graphene films. Shear-mixed graphene and ethyl cellulose is also shown to improve electrochemical performance in lithium-sulfur batteries when coupled with metal-organic frameworks, forming a ternary nanocomposite slurry that improves sulfur utilization, mitigates polysulfide shuttling, and improves electrical conductivity. Overall, these results demonstrate that graphene nanocomposites obtained through novel manufacturing and processing techniques are an inexpensive, energy-efficient route for consumer-scale implementation in nascent energy storage technologies. Furthermore, good compatibility of the graphene nanocomposites with additive manufacturing techniques results in high-quality printed electronic-grade conductive films. Although novel manufacturing and processing techniques are demonstrated here with graphene, further optimization and nanoscale studies of the dynamics of post-graphene 2D nanomaterials may lead to their implementation on the industrial scale using these techniques. In summary, the advent of continuous, scalable manufacturing strategies for graphene established in this thesis has the potential to catapult nanomaterials research into the next age of consumer electronics, where they can have considerable impact on grand challenges in energy, computing, and healthcare.

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