Scalable Assembly of Flexible and Thermally Conductive Graphene Paper Macroscopic Structures for Effective Thermal Management in Electronic Devices

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Innovative thermal management solutions to address ever-increasing challenges of heat generation are critical for future higher power, more compact and ultra-lightweight electronics. Current state-of-the-art materials such as flexible graphitic films for thermal management of high power electronics are not cost-effective since they are expensive to manufacture. Graphene, a single layer of carbon atoms bonded in a hexagonal lattice, is one of the thinnest and strongest of materials, and also displays intrinsically exceptional thermal conductivity. Macroscopic graphene structures, assembled from single layer graphene nanosheets, offer immense potential as advanced materials for effective thermal management. However, key challenges exist for the scalable assembly of two-dimensional graphene nanosheets into three-dimensional macroscopic structures, which is usually accompanied by a significant reduction of the thermal properties. To find solutions to address these key challenges, this award supports fundamental nano-scale manufacturing science of effectively assembling graphene nanosheets into large-scale three-dimensional architectures that are designed for performance in a cost-effective manner. These assembled macroscopic structures are highly flexible, mechanically robust and exceptionally thermal conductive, unlocking the enormous commercial potential of graphene as advanced materials for nano-scale thermal management. The results from this project will benefit the US economy and society. This project has synergistic educational and outreach impacts through integration of research and education and engaging participation of underrepresented groups.This project will develop innovative approaches of integrating two well-established industrial processes of electrospray deposition and roll-to-roll processing for manufacturing flexible graphene papers with breakthrough thermal properties. The research will establish process-microstructure-property relationships in electrospray deposited and assembled graphene papers through experimentation. Post-assembly high temperature annealing and mechanical compaction for microstructural optimization and graphene sheet alignment will be performed in order to improve properties. A game-changer is the direct manufacturing of the graphene nanosheets from defect-free graphene using electrospray deposition. Superior properties will be achieved in the macroscopic graphene structure without the penalty of traditional energy-intensive high temperature annealing. The scalable and cost-effective approach developed in assembling two-dimensional nanosheets into three-dimensional functional architectures will have a broader impact on controllable assembly and design of functional architectures of other two-dimensional single atomic layer materials beyond graphene.