Advanced Phase Change Composite by Thermally Annealed Defect-Free Graphene for Thermal Energy Storage

Abstract

Organic phase change materials (PCMs) have been utilized as latent heat energy storage and release media for effective thermal management. A major challenge exists for organic PCMs in which their low thermal conductivity leads to a slow transient temperature response and reduced heat transfer efficiency. In this work, 2D thermally annealed defect-free graphene sheets (GSs) can be obtained upon high temperature annealing in removing defects and oxygen functional groups. As a result of greatly reduced phonon scattering centers for thermal transport, the incorporation of ultralight weight and defect free graphene applied as nanoscale additives into a phase change composite (PCC) drastically improve thermal conductivity and meanwhile minimize the reduction of heat of fusion. A high thermal conductivity of the defect-free graphene-PCC can be achieved up to 3.55 W/(m K) at a 10 wt % graphene loading. This represents an enhancement of over 600% as compared to pristine graphene-PCC without annealing at a comparable loading, and a 16-fold enhancement than the pure PCM (1-octadecanol). The defect-free graphene-PCC displays rapid temperature response and superior heat transfer capability as compared to the pristine graphene-PCC or pure PCM, enabling transformational thermal energy storage and management.

Graphene nanoplatelet-fly ash based geopolymer composites

“…Compared to monolayer graphene, graphene nanoplatelets (GNPs) are formed by several layers of graphene and are less prone to agglomeration and entanglement because of the increased thickness of up to approximately 100 nm [19]. By contrast to graphene oxide (GO), graphene nanoplatelets (GNPs) have emerged as a competitive, alternate material for graphene because thermal annealing or chemical treatment can eliminate functional groups on GO to produce GNPs [19,20]. Furthermore, in comparison with carbon nanotubes (CNTs) for which only one side of the atomic lattice contacts the matrix and the other side of the lattice faces into the center of the tube, both faces of graphene contact the matrix.…”

Nanoconfinement of phase change materials within carbon aerogels: phase transition behaviours and photo-to-thermal energy storage

“…57,58 When octadecanol was inltrated into this carbon aerogel, the phase change process was inuenced, due to a disturbance to the crystal structure of the PCM by the aerogel, which implied a novel strategy for altering the phase change temperature of PCMs. 57,58 When octadecanol was inltrated into this carbon aerogel, the phase change process was inuenced, due to a disturbance to the crystal structure of the PCM by the aerogel, which implied a novel strategy for altering the phase change temperature of PCMs.…”

High‐Performance Thermally Conductive Phase Change Composites by Large‐Size Oriented Graphite Sheets for Scalable Thermal Energy Harvesting

“…Introducing nanoscale or micron‐sized carbon materials as fillers is the most frequently used way to improve Κ PCM . Carbon nanomaterials, such as graphite nanoplatelets (GNPs), multilayer graphene (MLG), and graphene, are obtained by mechanically cleaving or chemically exfoliating the layered van der Waals (vdW) material of graphite flakes and generally have a high aspect ratio and ultrahigh intrinsic in‐plane TC ( Κ > 1500 W m −1 K −1 at room temperature) . The thermal conductivity enhancement (TCE, TCE = ( Κ comp – Κ PCM )/ Κ PCM ) is mainly dependent on the filler loading, interface thermal resistance between filler and PCM, and the geometric and dimensional properties of the filler including lateral size, thickness, and sheet orientation .…”

“…To investigate the size effect of the graphite sheet on the TCE, we first compared the TCs of different compressed graphite blocks made from WEG and WEG ultrasonically pulverized for 15, 30, and 60 min (named as 15‐WEG, 30‐WEG, and 60‐WEG). The ultrasonic treatment destroys the vdW interactions between adjacent GNPs and is generally used to further exfoliate WEG into individual GNPs or MLG . The average length and diameter of raw WEG are 2.2 and 0.5 mm, respectively (Figure S6, Supporting Information).…”