High Thermal Conductivity of Carboxyl-rich Carbon/Polyethylene Glycol Composites for Enhanced Photothermal Conversion and Latent Heat Storage

Main observation and conclusion Polyethylene glycol (PEG) as phase change material (PCM) and carboxyl-rich carbon (RHTC) with different carboxyl content was introduced to prepare RHTC/PEG composites. The composites have high thermal conductivity, photothermal conversion ability, and improved the phase change enthalpy of the system. The microstructure and thermal properties of the samples were analyzed by various characterization methods. RHTC promoted the benign growth of PEG crystallinity (110.0%), influenced the phase change enthalpy of PEG, and improved the latent heat storage capacity of composites. The non-leakage loading of PEG in the composites can be as high as 97 wt%, and the actual phase change enthalpy is 10.7 J/g higher than that of pure PEG, 10% higher than the theoretical value. Owing to the heat storage bridge formed between PEG and RHTC, the thermal conductivity of the composites was up to 0.51 W/mK, which was 99.4% higher than that of PEG. Besides, the introduction of environmentally friendly and low-cost RHTC gives the composites excellent photothermal conversion capability, and its photothermal conversion energy storage efficiency is as high as 90.1%. These results prove that the prepared composites are promising potential candidates in the field of thermal storage and thermal management systems.