Nano-Engineered Organic Solid-Solid Phase Change Materials for High-Efficiency Thermal Energy Storage in Renewable Systems: A Review

Abstract

Thermal Energy Storage (TES) plays a critical role in enhancing the efficiency and sustainability of renewable energy systems. Among TES technologies, Phase Change Materials (PCMs) are widely used due to their high latent heat storage capacity. However, conventional solid-liquid PCMs suffer from leakage, structural instability, and volume expansion, limiting their practical applications. Organic solid-solid PCMs offer a promising alternative by maintaining their structural integrity while undergoing phase transitions. Recent advancements in nanotechnology have further enhanced the thermal properties of organic solid-solid PCMs, improving thermal conductivity, phase transition temperature control, and energy storage efficiency. This study explores the nano-engineering of organic solid-solid PCMs by incorporating nanomaterials such as metal oxides (TiO2, CuO, Al₂O₃, ZnO), carbon-based nanomaterials (graphene, carbon nanotubes), and metallic nanoparticles (Cu, Ag). These Nano-Engineered Organic Solid-Solid PCMs (NEOSS-PCMs) exhibit superior thermal performance, making them ideal for applications in solar energy storage, passive building temperature regulation, and electronic thermal management. Composite and nano-encapsulation techniques are investigated to improve stability and prevent degradation. This highlights recent advancements, key challenges, and future research directions in the development of high-efficiency nano-engineered organic solid-solid PCMs for TES in renewable energy systems.