Opportunities in thermal energy storage: Where phase change materials meet aerogels

Thermal energy storage (TES) is a key enabler for improving energy efficiency and supporting the integration of renewable energy systems. Among available TES technologies, phase change materials (PCMs) are attractive due to their high latent heat storage capacity and near-isothermal operation. However, their practical application is limited by inherent drawbacks such as low thermal conductivity, leakage during phase transition, and insufficient long-term stability. Aerogels, with their ultralow density, high porosity, and tunable surface chemistry, have emerged as highly effective scaffolding materials to overcome these limitations. This review presents a comprehensive and systematic assessment of PCM–aerogel composite systems, covering material fundamentals, fabrication strategies, thermophysical and multifunctional properties, and application-oriented performance. Key composite formation routes, including vacuum impregnation, sol–gel encapsulation, emulsion-based methods, electrospinning, and 3D printing-assisted architectures, are critically analyzed with respect to thermal conductivity enhancement, latent heat preservation, cycling durability, and shape stability. A performance-oriented framework and standardized cross-comparison approach are introduced to enable meaningful evaluation across diverse composite systems. The review further surveys representative applications in solar energy systems, electronics and battery thermal management, building energy efficiency, and functional textiles. Finally, remaining challenges related to scalability, cost, and testing standardization are discussed, and future research directions are outlined, highlighting the role of bio-based aerogels, hierarchical porous architectures, and multifunctional fillers in advancing the practical deployment of PCM–aerogel composites.