Recent advances in phase change materials for thermal energy storage-a review

The research on phase change materials (PCMs) for thermal energy storage systems has been gaining momentum in a quest to identify better materials with low-cost, ease of availability, improved thermal and chemical stabilities and eco-friendly nature. The present article comprehensively reviews the novel PCMs and their synthesis and characterization techniques for improving the properties and long-term storage capabilities. They include eco-friendly PCMs based on wood and tree fruit oils, microPCMs, nanoconfinement of organic PCMs, metal organic PCMs, bio-based PCMs, metal organic framework (MOF) PCMs and form-stable PCMs with gelators. The novel approaches such as cryogenically treated microencapsulated PCMs and treating them with photo-switching dopants to improve the properties are also presented. This review provides the useful insights about recent advances in the field of PCMs. The phase change slurries can effectively improve the thermal performance of photovoltaic/thermal systems. The thermal conductivity of PCMs can be enhanced significantly by PCM slurries, MOFs, exfoliated graphite nanoplatelets and composite PCMs. Optical control of PCMs by doping them with azobenzene dopants is found to be the most promising technique to improve the thermal stability and long-term storage capacity of PCMs. Cyclic cryogenic treatment by liquid nitrogen followed by heat treatment of PCMs can improve the latent heat, thermal and chemical stabilities significantly. The insightful information presented in this article can serve as an important tool for the researchers in the field of PCMs research to further innovate the technology in different applications such as thermal management of buildings, solar energy storage and cryogenic storage etc.