Microsphere Structure Composite Phase Change Material with Anti‐Leakage, Self‐Sensing, and Photothermal Conversion Properties for Thermal Energy Harvesting and Multi‐Functional Sensor

Abstract

The low thermal conductivity and liquid melt leakage of phase change materials are long-standing bottlenecks for efficient and safe thermal energy harvesting. Although high thermal conductivity materials combined with phase change materials can address the thermal conductivity problem, ensuring no leakage and no reduction in latent heat in the meantime remains challenging. Here, a strategy to synthesize microsphere-structured phase change composites by encapsulating phase change materials in graphene via emulsion polymerization (no additional emulsifier) and chemical reduction is proposed. Multiple graphene sheets are connected to construct an efficient thermally conductive (increase 58.5 times in thermal conductivity) and electrically conductive network. The composite microspheres exhibit no leakage (<0.5%) and superior phase transition behavior after 1500 heating-cooling cycles, and sense external environments such as temperature changes and water drops falling, allowing them to be engineered into devices for temperature monitoring. In addition, it converts electrical energy into thermal energy to achieve rapid temperature increases. The incorporation of polydopamine improves the photothermal efficiency of the phase change microspheres and senses light irradiation, offering a promising route to extend the single source of thermal energy. This method provides new insight into the photothermal integration and intelligent sensing of phase-change materials.

High-Quality Anisotropic Graphene Aerogels and Their Thermally Conductive Phase Change Composites for Efficient Solar–Thermal–Electrical Energy Conversion

“…It is seen in Figure 5a that the DSC heating curves of paraffin wax and PPG phase change composites exhibit two endothermic peaks during the melting process. The small peak at ∼40 °C corresponds to a solid−solid transition from a crystalline phase to a rotating body phase, implying a transition from an ordered to a disordered phase, 8 while the large peak at ∼58 °C is related to the solid−liquid phase transition, where the paraffin molecules get rid of the rigid structure and turn into a weakly restricted state. 8 The similar pattern is also observed during the exothermic solidification process (Figure 5b).…”

“…As a type of important thermal energy storage medium, organic phase change materials (PCMs) have high energy density, narrow phase change temperature range, and no supercooling . The PCMs can reversibly store and release thermal energy via their phase transitions, which is beneficial for alleviating the mismatch between the demand and supply of thermal energy .…”

“…Thermal energy storage technology is a feasible strategy to improve the utilization efficiency of energy, 5 exhibiting broad application prospects in the utilization of solar energy 6 and waste heat. 7 As a type of important thermal energy storage medium, organic phase change materials (PCMs) have high energy density, 8 narrow phase change temperature range, 9 and no supercooling. 10 The PCMs can reversibly store and release thermal energy via their phase transitions, 11 which is beneficial for alleviating the mismatch between the demand and supply of thermal energy.…”

Phase Change Materials for Life Science Applications

“…This is an efficient and scalable technique that provides new insight into multi-functional PCMs, thermal energy harvesting devices, and intelligent sensing and smart application of PCMs. [20] Non-paraffin, organic PCMs, are esters, fatty alcohols, glycols, and FAs, for instance, 1-tetradecanol lauric acid, acetic acid, 1-dodecanol capric acid, 9-heptadecanone, oleic acid, acetamide, and phenylacetic acid. These materials have different properties, however, they all have a few common qualities, some advantageous and others unfavorable, such as huge fusion temps and no or restricted supercooling for FAs, and instability at high temperatures, low thermal conductivity, and inflammability.…”

“…This is an efficient and scalable technique that provides new insight into multi‐functional PCMs, thermal energy harvesting devices, and intelligent sensing and smart application of PCMs. [ 20 ]…”