Interface-mediated extremely low thermal conductivity of graphene aerogel

Abstract

Due to the ultra-high thermal conductivity () of graphene, graphene-based materials are expected to be good thermal conductors. Here, however, we uncovered extremely low  of ultralight graphene aerogels (GAs). Although our GA (~4 mgcm-3) is about two times heavier than air (~1.2 mgcm-3), the  (4.7×10-3-5.9×10-3 W•m-1 •K-1) at room temperature (RT) is about 80% lower than that of air (0.0257 W•m-1 •K-1 at 20 °C). At low temperatures, the GA's  reaches a lower level of 2×10-4 4×10-4 W•m-1 •K-1. This is the lowest  ever measured to our best knowledge. The mechanism of this extremely low  is explored by studying the temperature variation of GA's , thermal diffusivity (α) and specific heat (c p) from RT to as low as 10.4 K. The uncovered small, yet positive /T reveals the dominant interface thermal contact resistance in thermal transport. For normal materials with thermal transport sustained by phononphonon scattering, /T always remains negative. The study of c p suggests highly disordered and amorphous structure of GAs, which also contributes to the ultralow . This makes the GA a very promising thermal insulation material, especially under vacuum conditions (e.g. astronautics areas).

3D Thermally Cross‐Linked Graphene Aerogel–Enhanced Silicone Rubber Elastomer as Thermal Interface Material

“…Compare to SR (0.23 W m −1 K −1 ), the TC of gGA/SR reaches 1.26 W m −1 K −1 increased by 448%. Moreover, the TC enhancement by per weight graphene (TCE per wt%) is as high as 896% which is much higher than the results in published literature as listed in Table S4 (Supporting Information). This is mainly determined by the 3D continuous high thermal conductive graphene framework, which provides fast paths for thermal conduction.…”

Tailoring Graphene Oxide‐Based Aerogels for Efficient Solar Steam Generation under One Sun

“…First, GO aerogels, with intentionally introduced multiwalled carbon nanotubes (MWCNTs), can enable broadband and efficient solar absorption (≈92%). Second, the intrinsic low thermal conductivity (<0.05 W m −1 K −1 ) of aerogels enables desirable heat localization for steam generation. Third, by addition of biocompatible sodium alginate (SA), GO aerogels demonstrate good hydrophilicity with water contact angle up to 74°.…”

“…Surface area measured by N 2 adsorption is found to be ≈125 m 2 g −1 (Figure S2, Supporting Information). The porous microstructures and defects on RGO sheets provide aerogels excellent thermal insulating properties, quick vapor escape as well as channels for liquid supply. The density of pressed RGO‐SA‐CNT aerogels is around 8 mg cm −3 , which allows the aerogels free‐floating on the top surface of water.…”

Advanced Materials for High‐Temperature Thermal Transport

“…The distinct feature of the superinsulators can be found in the density‐dependent behavior at a fixed temperature. Each mechanism of heat conduction follows the relation with the density where C 1 , C 2 , and C 3 are a constant. The negligible contribution of the κ solid leads to the increasing κ eff with the lower density.…”