Thermal conductivity improvement of composite carbon foams based on tannin-based disordered carbon matrix and graphite fillers

•Disordered carbon–graphite composite carbon foams were prepared.•Graphite filler improved the thermal conductivity by one order of magnitude.•Smaller graphite particles were shown to be the best for that purpose.•These materials meet the requirements for seasonal thermal storage applications.

Carbonaceous porous matrices were prepared from a tannin-based resin by physical foaming, having improved thermal properties by addition of various kinds and various amounts of graphite fillers. The resultant composite carbon foams presented much higher thermal conductivity, making them suitable for hosting phase-change materials with the aim of using them in seasonal storage applications. These materials were investigated in terms of porous structure, thermal and mechanical properties. It was shown that, unlike what was a priori expected, smaller particles were far more suitable for getting conductive, strong and porous matrices. The smaller were the particles, the better were the results. These findings were explained and justified, making such biomass-based composite carbon foams interesting and cheap candidates for thermal storage applications.

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