Nanoflake-Constructed Supramolecular Hierarchical Porous Microspheres for Fire-Safety and Highly Efficient Thermal Energy Storage

The leakage and fire hazard of organic solid–liquid phase change material (PCM) tremendously limit its long-term and safe application in thermal energy storage and regulation. In this work, novel nanoflake-fabricated organic–inorganic supramolecular hierarchical microspheres denoted as BPL were synthesized through the electrostatically driven assembly of poly(ethylene ammonium phenylphosphamide) (BP) decorated layered double hydroxides using sodium dodecyl sulfate as a template. Then the BPL was simultaneously utilized as a porous supporting material and flame retardant for polyethylene glycol to fabricate shape-stabilized PCM (BS-PCM). Benefiting from the structural uniqueness of the BPL microsphere, the BS-PCM possessed a high latent heat capacity of 116.7 J g–1 and excellent thermoregulatory capability. Moreover, the BS-PCM had no apparent leakage after a 200-cycle heating/cooling process and showed excellent thermal reversibility, superior to similar solid–liquid PCMs reported in recent literature. More interestingly, unlike flammable PEG, BS-PCM showed excellent fire resistance when exposed to a fire source. The unique BPL porous microsphere provided not only a microcontainer with high storage capacity for solid–liquid PCM, but also a fire resistant barrier to PEG, supplying a promising solution for highly efficient and fire-safe thermal energy storage.