Thermal transport measurement of three-dimensional graphene powders for application in energy devices

Three-dimensional graphene (3DG) has drawn much attention as a great potential electrode material for its extraordinary properties. However, the heat dissipation involved in the electrochemical reactions or Joule heating during the continuous charge-discharge cycles has become a critical challenge, which significantly affects the performance. In this work, we report the first experimental measurement on the thermal transport properties of 3DG powders under different temperatures and compressive stresses by using the laser flash method. High temperature and stress dependence of thermal transport in 3DG powders were observed from the measurements. The thermal diffusivity and thermal conductivity increase significantly from ~1.52 mm2/s to ~4.90 mm2/s and ~0.40 W/(m·K) to ~1.29 W/(m·K), respectively, with the temperature increment from 25°C to 120°C, corresponding to about 320% enhancement. Besides, we found the thermal conductivity quickly increases at the beginning and then gradually reaches to a saturation value of ~0.65 W/(m·K) with the increase of compressive stress. We proposed the temperature/stress-dependent thermal transport properties resulting from the reduction of thermal contact resistance, which dominates the thermal transport of porous material. These results provide useful guidelines for thermal design and benefit for effective thermal management of 3DG-based energy devices.