Effect of intermolecular explosion on thermal conductivity in multi-graphene structures

Abstract

We have developed a technological process for obtaining compacted multi-graphene structures (CMGSs) with the thermal conductivity of 500 W/(m×K). We propose the “Soft” regime of graphite intercalation procedure, which yields conglomerates with alternating stacks of five graphene layers, while the “Standard” regime is characterized by the formation of alternating stacks of three graphene layers. X-ray diffraction analysis and transmission electron microscopy studies of Soft and Standard CMGS have shown that the thermal conductivity of these materials is limited by defect density, size distribution, and misorientation of nanocrystallites. The effect of micro-deformations and residual macro-stresses on thermal conductivity of CMGS is discussed. The Soft method facilitated the formation of CMGSs with a less disrupted internal structure, characterized by increased nanocrystallites and reduced misorientation angles relative to the Standard approach, resulting in a 38% enhancement in thermal conductivity. A refined model is proposed that incorporates these key structural factors governing heat transport in CMGSs. The proposed method made possible the preparation of CMGS-based material with a thermal conductivity 25% higher and with a density five times lower than those of copper. Our findings demonstrate that precise regulation of the intermolecular explosion parameters enables the design of lightweight, flexible carbon-based materials with engineered thermal conductivity characteristics for advanced thermal-management applications.