Expanded graphite/graphene composites for high through-plane thermal conductivity

In view of the requirement of thermal management system in aerospace, heat-dissipating materials (HDMs) that possess exceptional thermal conductivity in the through-plane direction, especially for serving in harsh settings are immediately required. In the current work, an expanded graphite/graphene composite (EGC) by integrating graphene oxide (GO) into expanded graphite (EG) via a vacuum-assisted self-assembly method followed by compaction and graphitization was designed and constructed. The prepared EGC was endowed with remarkable thermal conductivity, whose through-plane and in-plane thermal conductivity achieved 18.6 and 129.9 W m−1 K−1, respectively with the optimized GO amount of 3.5 wt%. GO exhibited a pronounced bridging effect, facilitating the establishment of the phonon transmission "bridge" between the layers of EG. Notably, the "bridges" existed both within EG particles and among multiple EG particles, which dominated the thermal conductivity's augment in the composite. Moreover, the EGC demonstrated favorable compressive stress of 7.9 MPa at a 15 % strain ratio, exceeding that of EG.