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

创新的热管理解决方案，以应对不断增加的发热挑战，对于未来更高功率、更紧凑和超轻量化的电子产品至关重要。目前最先进的材料，如用于高功率电子设备热管理的柔性石墨薄膜，由于制造成本高昂，成本效益不高。石墨烯是以六角形晶格键合的单层碳原子，是最薄、最坚固的材料之一，也具有内在的特殊导热性能。由单层石墨烯纳米片组装而成的宏观石墨烯结构，为有效的热管理提供了巨大的潜力。然而，将二维石墨烯纳米片可伸缩地组装成三维宏观结构存在关键挑战，这通常伴随着热性能的显著降低。为了找到解决这些关键挑战的解决方案，该奖项支持基础纳米级制造科学，即有效地将石墨烯纳米片组装成大规模三维架构，这些架构旨在以经济高效的方式设计性能。这些组装的宏观结构具有高度的灵活性、机械坚固性和非凡的导热性能，释放了石墨烯作为纳米级热管理先进材料的巨大商业潜力。该项目的成果将造福美国经济和社会。该项目通过整合研究和教育，并吸引未被充分代表的群体参与，产生协同的教育和推广影响。该项目将开发创新的方法，整合两种成熟的工业工艺，即电喷雾沉积和卷对卷加工，以制造具有突破性热性能的柔性石墨烯纸。本研究将通过实验建立电喷雾沉积和组装石墨烯纸的工艺-组织-性能关系。为了改善性能，将进行组装后高温热处理和机械压实，以优化微观结构和石墨烯板材对齐。一种改变游戏规则的方法是使用电喷雾沉积从无缺陷的石墨烯直接制造石墨烯纳米片。宏观的石墨烯结构将获得优异的性能，而不会受到传统高耗能高温退火剂的影响。这种将二维纳米薄片组装成三维功能结构的可扩展和低成本的方法，将对石墨烯以外的其他二维单原子层材料的功能结构的可控组装和设计产生更广泛的影响。

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.