Thermal conductivity of 3-dimensional graphene papers

The thermal conductivities of low-defect 3D graphene materials synthesized by CVD processes have been investigated experimentally. The materials investigated were prepared using pure Ni powdered catalyst (giving graphene paper, GP, so called because the bulk structure is a paper, with a 3-dimensional interconnected graphene microstructure), or nickel/polymer catalyst (giving polymer-assisted graphene paper, pGP, or, with double-thick nickel/polymer catalyst, pGP×2), all with and without additional compression. Room-temperature thermal conductivity of the graphene materials generally increased with increasing density, with values as high as 40 W m−1 K−1 and specific thermal conductivity of up to 220 mW m2 kg−1 K−1, although the porosity was quite high (~90% or higher). We show that larger graphene flakes and higher density lead to better intrinsic thermal conductivity. For compressed pGP×2, we investigated the temperature-dependence of the specific thermal conductivity, and found a broad maximum from T ~ 270 to 330 K, at a value of 230 ± 20 mW m2 kg−1 K−1.