Linking Encapsulation, Thermal Transport and System Performance in Thermal Energy Storage Using Phase Change Materials

ABSTRACT Phase change materials (PCM) are widely investigated for thermal energy storage (TES) because of their high latent heat capacity and their potential to improve energy efficiency in solar‐energy systems, buildings and electronics. This review examines recent progress through three interconnected research directions: (i) encapsulation strategies and shell stability considerations; (ii) nanostructure‐enabled shape‐stabilized PCM (SSPCM) and their associated thermal‐transport mechanisms and (iii) widely adopted modeling approaches for describing melting and solidification under realistic boundary conditions. The review covers inorganic, organic and eutectic PCM and discusses representative thermophysical performance ranges including latent heat capacities of 120–240 kJ·kg −1 , thermal conductivity (TC) enhancement through graphene and boron nitride (BN) fillers by approximately 3–10 times and cycling stability of up to 2000 thermal cycles reported for optimized polymer‐shell systems. Applications in solar thermal storage, building energy management and electronics cooling are analyzed to demonstrate how material‐level engineering influences system‐level thermal performance, including area‐normalized thermal gain (0.3–1.4 kWh·m −2 ·day −1 ), PCM mass‐specific storage capacity (100–200 kJ·kg −1 ) and heat‐flux handling capability in electronics (10–40 W·cm −2 ). In addition, the review discusses practical engineering challenges associated with large‐scale manufacturing, cost, thermal reliability, material compatibility and long‐term operational stability. Unlike many existing reviews that separately discuss encapsulation methods, nanostructure enhancement or thermal modeling, this work provides a design‐oriented perspective linking material engineering, thermal transport behavior and system‐level TES performance. The reported performance metrics are discussed as comparative indicators, while acknowledging the influence of varying operating conditions and boundary parameters among different studies.