A novel low-energy and ultra-easy approach to preparing composite phase change material with high photo-/electro-thermal energy conversion and storage

Use of Phase Change Materials (PCM) for thermal energy storage has been a research hotspot in the field of energy storage. However, the development of composite PCM is always hindered by liquid leakage and poor photo-/electro-thermal conversion efficiency of PCM. In this work, inspired by the preparation of frozen tofu, a novel graphene foam (GF) was prepared by the method. Then polypyrrole (PPy) was successfully coated on the surface of GF by vapor phase deposition, to obtain GF@PPy. Finally, polyethylene glycol (PEG) was supported using GF@PPy, which effectively prevented the leakage of PEG, and successfully obtained a form-stable composite PCM (PEG/GF@PPy) with photo/electro-thermal conversion property. Research indicates that owing to the π-electrons in the molecular chain of PPy are freely movable, which endows PPy possess excellent electrical and thermal conductivity. It ultimately results in the introduction of PPy improve the thermal and electrical conductivity of composite PCM. It makes PEG/GF@PPy exhibit an effective electro-thermal conversion efficiency of 89.6 %. Moreover, PPy as an excellent photothermal conversion material, enhanced the photothermal conversion efficiency of PEG/GF@PPy up to 90.3 %. Finally, the composite PCM with photoelectric/electrical heat conversion property is applied to the field of thermotherapy. Comparison of popular thermotherapy products indicates that PEG/GF@PPy was able to provide longer duration of thermotherapy, up to 77.8 min. The strategy reported in this paper may assist in the preparation of composite PCM with high photo/electro-thermal conversion efficiency for use in the thermotherapy field.