A novel CFRP composite with bi-directional high thermal conductivity via quantum dots modified filler and electrodeposited Cu modified carbon fiber

Carbon fiber-reinforced polymer (CFRP) composite has low through-plane thermal conductivity (TC < 0.6 W/(m∙K)) due to the directional arrangement of carbon fibers (CFs) and low TC of resin, which seriously limits actual application. It is an effective method to improve TC by loading fillers and constructing continuous thermal conductive networks in the resin matrix. However, low surface roughness of CF causes poor interface performance, and inherent intervals among CF riveting points restrict the enhancement of through-plane TC. The preparation of CFRP composite with bi-directional high TC is still an enormous challenge. In this work, a novel CDs-EG/EP-CF@Cu composite with carbon dots (CDs) modified expanded graphite (EG) and Cu-modified CF is prepared by multilayer lamination and hot-pressing coupling method, where EG is utilized to construct 3D thermal conductive networks, CDs is employed to improve EG-epoxy interface compatibility and Cu-modified CF by electrodepositing is exploited to optimize the interface and construct nano-scale roughness. Results show that CDs-EG/EP-CF@Cu composite exhibits high bi-directional TC (8.75 W/(m∙K) through-plane TC and 36.97 W/(m∙K) in-plane TC). Besides, our composite exhibits excellent thermal responsiveness, electrical conductivity (18320 S m⁻¹), electromagnetic interference shielding (86.52 dB), and mechanics properties. This work provides a novel method to prepare bi-directional high TC CFRP composites.