Sb doped Al-Si/AlN composite phase change material with improved thermal conductivity and reliability

The propensity for leaks in high-temperature molten alloys greatly restricts their extensive use in storing high-temperature thermal energy. In tackling this matter, the research concentrates on Al-Si/AlN composite phase change materials (PCMs), incorporating the modifier Sb to significantly improve their heat conduction and thermal steadiness. The results reveal that incorporating Sb alters the Si phase from a bulk form to an elongated one, simultaneously triggering the creation of an Al-Si@Al₂O₃ core-shell configuration. This structural optimization reduces free electron scattering and extends the mean free path of electrons, thereby improving the thermal conductivity of the material. It was established that the ideal fraction of Sb mass is 0.6 %, where the thermal conductivity of the Sb-altered Al-Si/AlN composite PCMs attains 49.5 W/(m·K), marking a 15.2 % enhancement over the original Al-Si/AlN composite PCMs, with a latent heat of 351.5 kJ/kg. Additionally, the creation of the Al₂O₃ shell led to the altered materials showing remarkable thermal stability across 200 high-temperature thermal cycles, resulting in less than a 4 % decrease in latent heat post-cycle and no leakage detected. The study offers not just an innovative approach for creating advanced Al-Si/AlN composite PCMs but also broadens their use in storing thermal energy at high temperatures.