Preparation and characteristic of Ag nanoparticle modified expanded graphite for enhancing paraffin phase change material properties

Ag nanoparticles are a promising additive for enhancing the thermal conductivity of PCMs. In this study, a series high thermal conductive shape-stable composite phase change materials PCMs were prepared by absorbing the Paraffin (PW) into the Ag nanoparticles modified expanded graphite (Ag@EG). SEM and EDS results proved that Ag nanoparticles were uniformly modified onto EG. The XPS results for Ag@EG indicated that the valence state of Ag in the EG was mainly zero. The XRD and FT-IR results of Ag@EG/PW indicated that the composite PCMs (CPCMs) have good chemical compatibility. The PW capacity in all CPCMs reached upon 60% with the latent heat in the range of 124.4-112.2 J/g. The thermal conductivity of 3.9-AEP reached 3.98 W/m/K which was enhanced by 1890.0% and 170.3% compared with PW and 0-AEP, respectively. All CPCMs possessed good thermal stability and thermal reliability after 200 thermal cycles. This indicated that the form-stable composite PCMs of Ag@EG/PW were good candidate materials for thermal energy storage in solar energy storage systems.