Multiple structure graphite stabilized stearic acid as composite phase change materials for thermal energy storage

This paper used 3 types of graphite with different physical structures as the porous matrix to prepare composite phase change materials (PCMs), and investigated their photo-thermal conversion performance and application in battery thermal management. Multiple structure graphite minerals, including microcrystalline graphite (MG), scale graphite (SG), and expanded graphite (EG) were used as porous matrix, while stearic acid (SA) acts as the phase change material. The vacuum impregnation method was applied to prepare SA/MG, SA/SG, SA/EG, and SA/MG1, and SA/EG1was/were prepared by the ethyl alcohol method. Results show that the thermal conductivities of all composite phase change materials were 10.82 to 22.06 times higher than that of the pure SA. Thermogravimetric (TG) analysis showed that the loadages of SA were 43.61%, 18.74%, and 92.66% for SA/MG, SA/SG, and SA/EG respectively. The load rates of SA were 18.98% and 18.88% for SA/MG1 and SA/EG1, respectively. For the 3 types of graphite materials of different dimensions, the BET (Brunauer, Emmett, and Teller) surface area determines the maximum load of SA. The Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) results indicated that there was good compatibility between the SA and the supports. The SA/EG1 has better thermophysical properties in heat energy storage and release process. The thermal infrared images show that SA/EG1 has higher sensitivity to the temperature changes. SA/EG1 has better photo-heat conversion performance than SA/SG and SA/MG1 attributed to the multilayer structure of EG. SA/EG has better thermal management performance in the Li-ion batteries discharge process.