Phase Engineered Composite Phase Change Materials for Thermal Energy Manipulation

Abstract Phase change materials (PCMs) present a dual thermal management functionality through intrinsic thermal energy storage (TES) capabilities while maintaining a constant temperature. However, the practical application of PCMs encounters challenges, primarily stemming from their low thermal conductivity and shape‐stability issues. Despite significant progress in the development of solid–solid PCMs, which offer superior shape‐stability compared to their solid–liquid counterparts, they compromise TES capacity. Herein, a universal phase engineering strategy is introduced to address these challenges. The approach involves compositing solid–liquid PCM with a particulate‐based conductive matrix followed by surface reaction to form a solid–solid PCM shell, resulting in a core‐shell composite with enhanced thermal conductivity, high thermal storage capacity, and optimal shape‐stability. The core‐shell structure designed in this manner not only encapsulates the energy‐rich solid–liquid PCM core but also significantly enhances TES capacity by up to 52% compared to solid–solid PCM counterparts. The phase‐engineered high‐performance PCMs exhibit excellent thermal management capabilities by reducing battery cell temperature by 15 °C and demonstrating durable solar‐thermal‐electric power generation under cloudy or no sunshine conditions. This proposed strategy holds promise for extending to other functional PCMs, offering a compelling avenue for the development of high‐performance PCMs for thermal energy applications.