State-of-the-art review of mitigation techniques and performance enhancement methods of phase change materials for thermal energy storage technology.

While investigating fossil fuel alternatives, phase change materials (PCMs) are promising for thermal energy storage (TES) applications because of their high renewable energy storage density, constant phase transition temperature, affordable pricing, non-toxic nature, etc. However, several limitations, including liquid leakage, phase separation, supercooling, low thermal conductivity, and unalterable melting temperature, offer a challenge in their utilization. While numerous studies have addressed these issues, there is no universal solution for PCM challenges. Customized strategies are required to mitigate each drawback. This review paper provides a comprehensive summary of the mitigation techniques and enhancement methods employed and their influence on the thermophysical characteristics of these materials. Strategies to reduce supercooling involve incorporating nucleating agents, seeding, and microencapsulation. Eutectic PCMs with alterable melting temperatures can be designed to enable the use of a specific PCM in various applications. Shape-stabilized PCMs effectively prevent liquid leakage, which utilizes multiple support materials. Additionally, incorporating thickening agents to mitigate phase separation and enhanced heat transfer strategies through various methods, including nanomaterial additives, porous mediums, microencapsulation, and uniform heat transfer, are deeply discussed. The insights provided in this paper are valuable for selecting reliable PCMs and determining appropriate performance improvement methods to achieve optimal thermal performance in PCM-based TES systems. Furthermore, the article also proposes essential directions for the future advancement of PCMs.