Preparation and characterization of high-enthalpy inorganic hydrated salt phase change materials based on sodium silicate precursor

Phase change materials (PCMs) exhibit a promising application as a heat storage medium in battery thermal management. However, the flammability, low thermal conductivity, and leakage problems of organic PCMs constrain the development. In this study, a novel strategy based on inorganic hydrated salt with natural nonflammability was proposed. Sodium acetate trihydrate and disodium hydrogen phosphate dodecahydrate composite materials (SAT-DSP) were synthesized without affecting the properties. The prepared SD@SiO2 with sodium silicate as the precursor, while SAT-DSP as the core material, possessed the dual heat storage performance of phase transition and thermochemical heat storage. The SiO2 shell with a dense surface successfully realized the encapsulation of SAT-DSP, and the combined effect of heterogeneous nucleation and mesoporous confinement effectively inhibited the phase separation of phase change materials. The optimal ratio of SD@SiO2 was determined through a comprehensive analysis of morphology, thermal stability, and thermal storage properties. The heat storage density was up to 509.18 J g(-1) with a phase transition temperature of 78.78 degrees C. It improved the chemical instability and leakage of hydrated salts and centralized the dehydration process of SAT-DSP to achieve rapid response. Even after continuous heating on a 120 degrees C heating platform for 30 min, the surface temperature of SD@SiO2 was maintained within a safe range (< 65 degrees C). This inorganic phase change material exhibited considerable potential for application in battery thermal runaway protection.