Advanced encapsulation strategies for high-temperature molten salt: Synthesis methods and performance enhancement

Abstract

In the pursuit of a global paradigm shift in energy structure and carbon neutrality objectives, high-temperature thermal energy storage technologies have garnered significant attention due to their high efficiency and cost advantages. Latent heat storage utilizing molten salts demonstrates notable advantages including high energy density and isothermal phase change characteristics, playing crucial roles in industrial waste heat recovery, renewable energy utilization, and energy supply-demand balance regulation. Nevertheless, practical implementation is hindered by critical limitations, primarily molten salt leakage and equipment corrosion. Encapsulation technology has emerged as an effective mitigation strategy, enhancing system safety and longevity. This review systematically examines the latest advancements in molten salt encapsulation technology, focusing on three primary methods: melt infiltration, capsule method, and mixed sintering. Moreover, this review summarizes the impact of encapsulation strategies on molten salt phase change materials (PCMs) performance, including thermophysical properties, mechanical characteristics, cycling stability, and economic viability. Additionally, emerging research directions such as biomimetic design, multifunctional composite materials, and industrial waste utilization are extensively explored, highlighting their applications and potential advantages in molten salt encapsulation. Finally, the technical characteristics and advantages of encapsulated molten salts were analyzed across various configurations, including heat exchangers, finned systems, and cascaded phase change material (PCM) systems. The work aspires to inspire more innovative research, thereby driving technological breakthroughs in high-temperature energy storage applications of molten salt composite PCMs.