Progress of research on phase change energy storage materials in their thermal conductivity

In recent years, phase change materials (PCM) have become increasingly popular for energy applications due to their unique properties. However, the low thermal conductivity of PCM during phase change can seriously hinder its wide application, so it is crucial to improve the thermal conductivity of PCM. In this paper, the thermal conductivity mechanism of PCM (basic thermal conductivity, phonon thermal conductivity and channel thermal conductivity) and thermal conductivity prediction models (nano-type and foam-metal type) are systematically discussed from a microscopic perspective, providing a theoretical basis and a validation model for the study of thermal conductivity of PCM. In addition, we review three specific approaches to improve PCM from a macroscopic perspective: addition of nanoparticles, embedded foam structures, and addition of external fields. Finally, it is concluded that the specific approaches to improve the thermal conductivity of PCM all proceed to enhance the different thermal conductivity mechanisms of PCM, and future research directions to improve the thermal conductivity of PCM are proposed in response to this conclusion.