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A novel solid-to-solid phase change composite brick was prepared by combination of polyurethane (PU) and pitch-based graphite foam (PGF). The carbonaceous support, which can be used for mass production, not only greatly improves the thermal conductivity but promote electro-to-heat conversion efficiency of organic phase change materials (PCMs). Our composite retained the enthalpy of PCM and exhibited a greatly reduced supercooling temperature. The novel composite was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The enthalpy of polyurethane has increased about 8.6% after infiltrating into graphite foam. The composite was very stable during thermal cycle test, and the electro-to-heat conversion efficiency achieves to 85% at lower voltages (1.5–1.8 V), which can vastly reduce energy consumption. The as-prepared composite was used in a wear layer to test its performance comparing with normal fabric.

Owing to the high energy density of phase change materials, latent heat storage systems have been an effective strategy for the improvement of energy efficiency. The severe limitations of their extensive application are the potential leakage and low thermal conductivity. Herein, we developed a facile dual-encapsulation method to solve the abovementioned problems in the phase change composite composed of octadecanol, a high thermal/electrical conductive macroporous graphite foam and a thin waterborne polyurethane (WPU) film. After dual-encapsulation, the thermal conductivity of the composite was 20 times higher than that of pure phase change material (PCM) octadecanol. As a result, the composite exhibited a reduced supercooling degree and rapid thermal energy charging behaviors, as well as electro-to-heat conversion ability. This study gives a new perspective for the synergistic enhancement of both the thermal and electric conductivity of functional PCMs for thermal energy storage and conversion.

Organic phase change materials (PCMs) have exhibited many promising potentials for thermal energy conversion and storage, but they are still confronted with many technical bottlenecks for practical application, such as low conductivity, leakage during phase transition process, and lack of functionality. In this article, a highly-efficient electro/photo to heat conversion system of polyurethane@graphite foam (PU@GF) phase change composites was successfully fabricated through in situ polymerization of polyethylene glycol (PEG) in GF. The obtained PU presents solid–solid phase transition behavior that is different from the solid–liquid phase change of original PEG, which can prevent PU from leakage even if it was loaded in micrometer pores in the GF during application. On the other side, PU can improve the thermal stability and decrease the overcooling degree of the composites in effect. Excellent conductive network was provided by the GF, with which the light absorption and thermal conductivity of the composites were enhanced dramatically. Consequently, the solid–solid phase change composites can effectively store electricity or sunlight energy. The electro-heat storage efficiency of the composites can exceed 80% at 1.2 or 1.4 V, meanwhile, the photo-heat storage efficiency can close to 67% under simulated solar illumination. This result presents the highest efficiency for electro-to-heat conversion by PCMs techniques driven by a quite low voltage up to now, and will give rise to a new expectation of functional PCM application for energy conversion and storage.

Phase transition is a natural phenomenon happened around our daily life, represented by the process from ice to water. While melting and solidifying at a certain temperature, a high heat of fusion is accompanied, classified as the latent heat. Phase change material (PCM) has been widely applied to store and release large amount of energy attributed to the distinctive thermal behavior. Here, with the help of nanoporous materials, we introduce a general strategy to achieve the binary eicosane/PEG4000 stuffed reduced graphene oxide aerogels, which has two ends with different melting points. It's successfully demonstrated this binary PCM composites exhibits thermal rectification characteristic. Partial phase transitions within porous networks instantaneously result in one end of the thermal conductivity saltation at a critical temperature and therefore switch on or off the thermal rectification with the coefficient up to 1.23. This value can be further raised by adjusting the loading content of PCM. The uniqueness of this device lies in its performance as a normal thermal conductor at low temperature, only exhibiting rectification phenomenon when temperature is higher than a critical value. The stated technology has broad applications for thermal energy control in macroscopic scale such as energy-efficiency building or nanodevice thermal management.