Photo-to-thermal conversion and energy storage of polyethylene glycol/copper sulfide composite PCMs

In order to improve the energy storage performance of polyethylene glycol (PEG), copper sulfide (CuS) was introduced into PEG to endow the function of photo-to-thermal conversion. A series of novel PEG/CuS composite phase change materials (PCMs) were prepared by melt blending method with polyethylene pyrrolidone (PVP) employed as a stabilizer. Results of the dispersion stability experiment and 100 thermal cycles test showed that 2 wt% PVP can effectively improve the stability of PEG/PVP/CuS composite PCMs. And the CuS nanoparticles were uniformly dispersed in the PEG through physical action with the help of PVP. DSC results showed that the melting enthalpy of PEG/PVP/CuS composite PCM is as high as 171.8 J/g, 164.0 J/g, and 156.2 J/g when the content of CuS is 2 wt%, 6 wt%, and 10 wt%, respectively. Thermal cycling test and TGA results demonstrated that PEG/PVP/CuS composite PCMs have excellent reliability and stability. The photo-absorption property of PEG/PVP/CuS composite PCM increases to the range of 0.44–0.852, 0.938–1.533, 1.335–2.462 respectively within the addition of 2 wt%, 6 wt%, 10 wt% CuS in the radiation range of 300–900 nm. And the photo-to-thermal conversion efficiency of PEG/PVP/CuS composite PCMs was tested up to 87.36%. Therefore, the prepared PEG/PVP/CuS composite PCMs show remarkable potential in solar thermal utilization applications.