Low thermal conductivity and corrosion problem of NaNO₃ salt-based phase change materials (PCMs) are regarded as two critical barriers for their applications in thermal energy storage. To address the above problem, a diatomite-based porous ceramic modified by CaCO₃ was firstly used to develop shape-stabilized NaNO₃ in this work. Particularly, contribution of modified diatomite-based ceramic on improving thermal conductivity of the composite was investigated. Compared with traditional diatomite-based skeleton, diatomite-based ceramic was found to contribute to a 129% higher thermal conductivity of composites, benefited by the generation of a dense and continuous skeleton that consisted of newly formed cristobalite phase with a higher thermal conductivity. While crack occurred on the composite with diatomite-based ceramic after 100 thermal cycles, resulting in the leakage of salt and the decrease of thermal conductivity. By contrast, diatomite-based ceramic modified by no more than 40 wt% CaCO₃ effectively avoided the crack of composites, exhibiting quite a stability in shape and thermal conductivity during 500 thermal cycles. The modified ceramic was shown to improve the thermal conductivity of loaded NaNO₃ by 118%, up to 1.22 W/(m·K) at 25 °C. The results also indicated that the modified ceramic hardly changed the phase transition temperature of NaNO₃, but decreased the latent heat of composites, while possessed a much higher capacity to load salt (57 wt% NaNO₃) than that of other porous ceramics. The composite with modified ceramic was demonstrated to have a good cycling stability in thermal properties as well, which performed a considerable potential in thermal energy storage.

NaNO ₃盐基相变材料(PCM)的低导热性和腐蚀问题被认为是其在热能存储中应用的两个关键障碍。针对上述问题，首次采用CaCO ₃改性硅藻土基多孔陶瓷开发形状稳定的NaNO ₃在这项工作中。特别地，研究了改性硅藻土基陶瓷对提高复合材料热导率的贡献。与传统的硅藻土基骨架相比，硅藻土基陶瓷的复合材料热导率提高了 129%，这得益于由新形成的具有更高热导率的方石英相组成的致密连续骨架的生成。而硅藻土基陶瓷复合材料经过100次热循环后出现裂纹，导致盐分泄漏，导热系数降低。相比之下，由不超过 40 wt% CaCO ₃改性的硅藻土基陶瓷有效避免了复合材料的裂纹，在500次热循环中表现出相当的形状稳定性和导热性。结果表明，改性陶瓷将负载的 NaNO ₃的热导率提高了118%，在 25 °C 时达到 1.22 W/(m·K)。结果还表明，改性陶瓷几乎没有改变NaNO ₃的相变温度，但降低了复合材料的潜热，同时具有比其他多孔陶瓷更高的载盐能力（57 wt% NaNO ₃）。具有改性陶瓷的复合材料在热性能方面也具有良好的循环稳定性，在热能储存方面具有相当大的潜力。