Synthesis and Properties of Polyurethane/Coal-Derived Carbon Foam Phase Change Composites for Thermal Energy Storage

In this article, we used coal-derived carbon foam (CCF) as a skeleton material to encapsulate the solid-to-solid phase change material polyurethane (PU) to provide PU@CCF composites for functional applications. The obtained PU@CCF composites were characterized by field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and thermal conductivity measurements. The results illustrated that the most preferred ratio of polyethylene glycol (PEG-6000) to hexamethylene diisocyanate (HDI) to synthesize PU was 1 : 2 and the CCF skeleton prevented PU leakage during the phase change process. Compared with PEG-6000, the thermal conductivity of the PU@CCF composite was raised by 54%, its cycle thermal stability was remarkable after 2000 cycles, and its supercooling degree was lowered by more than 10 degrees C. For electro-to-heat energy conversion, the phase transition behavior of the obtained PU@CCF could be induced under an electron voltage as low as 0.8 V with 75% conversion efficiency at 1.1 V. This functional phase change composite realizes electric-heat conversion under the lowest loading voltage reported to date, providing an important benchmark for the preparation and functionalization of low-cost phase change composites.