Phase Change Materials Composite Based on Hybrid Aerogel with Anisotropic Microstructure

Abstract

Phase change materials (PCMs) can be thermally enhanced by reduced graphene oxide (rGO)/expanded graphite (EG) aerogel with anisotropic microstructure. An rGO/EG aerogel with anisotropic microstructure was prepared by directionally freezing aqueous suspensions of graphene oxide (GO) and EG, followed by a freeze-drying process and thermal reduction at 250 °C. The anisotropic microstructure of rGO/EG aerogel composite PCM was confirmed by scanning electron microscopy (SEM), thermal conductivity tests and infrared images. The thermal conductivity of PCMs increased remarkably with rGO/EG aerogel. Compared with the thermal conductivity of pure paraffin, it increased by about 50~300% in the longitudinal direction and increased by about 25–150% in the transversal direction. The enhancement of thermal conductivity was attributed to the improvement of the thermal pathway provided by rGO/EG aerogel and the decrease of the interfacial thermal resistance between PCM and fillers. Meanwhile, rGO/EG aerogel was combined with paraffin only by physical adsorption, and no chemical interaction occurs between them, leading to no effect on the phase change behavior. In addition, the addition of rGO/EG aerogel led to a slight increase in the latent heat of the paraffin in the composite PCM.

Thermal‐Conductivity‐Enhancing Copper‐Plated Expanded Graphite/Paraffin Composite for Highly Stable Phase‐Change Materials

“…PA has a large latent heat performance, but its thermal conductivity is extremely poor, and the thermal conductivity is generally 0.2–0.4 W/(m ⋅ K), [15,37] which greatly limits the application of PA as a phase change material. Its thermal conductivity can be enhanced by adding thermally conductive materials such as expanded graphite (EG), graphene, carbon nanotubes, carbon fibers, Cu mesh, Al foam, etc [16–23,38–39] . In this work, low‐cost EG is used as the supporting material and dominant thermal conductive material, and CPEG is used as the thermal conductivity enhancer to improve the thermal conductivity of PA. As shown in Figure 11, the thermal conductivity of the E10C0 composite is about 10 times higher than that of pure PA, indicating that the addition of EG significantly improves the thermal conductivity, which is consistent with the literature [1,24] .…”

“…The research on paraffin (PA)/expanded graphite (EG) composite phase change materials have attracted widespread attention because expanded graphite has the advantages of low cost, good pore structure ensuring large amount of paraffin adsorbed, and high thermal conductivity. [9][10][11][12] For example, by using 20 % EG as the thermal conductive material and supporting material, 80 % PA as the phase change material, Luo et al [12] successfully prepared a composite phase change material with good thermal conductivity, which successfully reduced the temperature from 77 °C to 43 °C for Li-ion battery operating at a rate of 3 C. To further improve the thermal conductivity, recent literatures have reported the research on adding thermal conductivity enhancing materials such as active carbon, [16] graphene, [17][18] carbon fiber, [19] multiwalled carbon nanotubes, [18] Cu mesh, [20] Cu foam [21]] , and Al foam [22][23] to the PA/EG composite phase change material. For example, Li et al [17] added graphene aerogels to the PA/EG composite phase change material, which increased the thermal conductivity by 300 %.…”

“…[9][10][11][12] For example, by using 20 % EG as the thermal conductive material and supporting material, 80 % PA as the phase change material, Luo et al [12] successfully prepared a composite phase change material with good thermal conductivity, which successfully reduced the temperature from 77 °C to 43 °C for Li-ion battery operating at a rate of 3 C. To further improve the thermal conductivity, recent literatures have reported the research on adding thermal conductivity enhancing materials such as active carbon, [16] graphene, [17][18] carbon fiber, [19] multiwalled carbon nanotubes, [18] Cu mesh, [20] Cu foam [21]] , and Al foam [22][23] to the PA/EG composite phase change material. For example, Li et al [17] added graphene aerogels to the PA/EG composite phase change material, which increased the thermal conductivity by 300 %. Wu et al [20] successfully prepared a PA/EG/Cu mesh composite phase change material with remarkable increased thermal conductivity.…”

Aerogels Meet Phase Change Materials: Fundamentals, Advances, and Beyond

“…In addition to single AGAs, Li et al 127 prepared anisotropic rGO/EG hybrid aerogels by directional freezing. The longitudinal thermal conductivity of the obtained composite PCMs was 0.79 W/m•K when the content of rGO/EG aerogels was 8.7 wt %, which was almost four times higher than pristine paraffin.…”

AlN micro-honeycomb reinforced stearic acid-based phase-change composites with high thermal conductivity for solar-thermal-electric conversion

“…Owing to the merits of excellent theoretical TC, high electric insulating performance, high mechanical strength, good reliability and chemical stability, [31][32][33][34][35] AlN ceramic is a promising TC-enhanced ller for improving the TC of phase-change composites. 5,36 Enlightened by the above-mentioned studies, the introduction of a vertically aligned and thermal-conductive AlN network constructed by freeze-casting into an organic phase-change matrix should be an effective method to strengthen the heat conduction of PCMs.…”