Enhanced thermal conductivity of phase change materials with ultrathin-graphite foams for thermal energy storage

Abstract

For thermophysical energy storage with phase change materials (PCMs), the power capacity is often limited by the low PCM thermal conductivity (κ_PCM). Though dispersing high-thermal conductivity nanotubes and graphene flakes increases κ_PCM, the enhancement is limited by interface thermal resistance between the nanofillers, among other factors such as detrimental surface scattering of phonons. Here, we demonstrate that embedding continuous ultrathin-graphite foams (UGFs) with volume fractions as low as 0.8–1.2 vol% in a PCM can increase κ_PCM by up to 18 times, with negligible change in the PCM melting temperature or mass specific heat of fusion. The increase in κ_PCM, thermal cycling stability, and applicability to a diverse range of PCMs suggests that UGF composites are a promising route to achieving the high power capacity targets of a number of thermal storage applications, including building and vehicle heating and cooling, solar thermal harvesting, and thermal management of electrochemical energy storage and electronic devices.