A review of phase change materials: Selection, degradation, and materials compatibility

As concerns about climate change and excess energy requirements intensify, thermal energy storage (TES) systems have emerged as a promising solution by enabling the storage of excess heat. One of the technologies uses phase change materials (PCMs), which have appeared as an alternative to enhance the performance of renewables (i.e., solar, geothermal) by acting as thermal storage batteries. This paper presents a comprehensive review of latent heat TES systems, emphasising the critical criteria for selecting PCMs used in these applications. Additionally, the categories of the available PCMs are presented. This review also discusses their thermal stability over time, as PCMs can experience performance degradation due to repeated heating and cooling cycles or prolonged exposure to high temperatures. Furthermore, the paper highlights the importance of compatibility between PCMs and structural materials, summarising the interaction of various metals and alloys, and polymers in contact with different PCMs. Compatibility could ensure the long-term operational reliability of TES systems. The paper further presents the challenges and considerations for the large-scale deployment of PCM-based TES systems.