Abstract:

Solid-liquid phase-change materials (PCMs) are abundant in variety and have relatively high latent heat, thus making them important working media for latent heat storage systems. Combining solid-liquid PCMs with porous supporting materials is an effective way to improve their application performance and service life. Metal-organic frameworks (MOFs) is a new kind of porous material, which has advantages of large specific surface area, high porosity, adjustable pore size and surface properties, thereby making them promising supporting materials for solid-liquid PCMs. This paper thoroughly reviewed the MOF-based composite PCMs. Specifically, the composite PCMs directly employing the MOFs as the supporting materials, the composite PCMs employing the MOFs derived porous carbon materials as the matrices, and the composite PCMs employing the hybrid materials prepared by in-situ growing MOFs on thermally conductive matrices as the carriers, are introduced respectively. The strong capillary force generated by the microporous structure of MOFs had a strong fixation effect on the solid-liquid PCMs. Synthesizing the MOFs with large pore sizes or modifying the MOFs to adjust its interactions with the PCMs are useful to increase the loadings of the PCMs and thus the latent heat of the obtained composite PCMs. Carbonizing the MOFs at high temperatures to obtain MOFs derived porous carbon materials could enlarge the pores of the MOFs, and the accompanying nitrogen and phosphorus doping could enhance the hydrogen bonding between the supporting materials and PCMs, all of which helped to acquire the composite PCMs with high loadings and latent heat. The in-situ growing MOFs on thermally conductive matrices to build a continuous heat transfer network could effectively enhance the thermal conductivity of the obtained composite PCMs. The thermal conductivity of the composite PCMs could be further increased by employing the hybrid materials prepared by carbonizing the in-situ growing MOFs thermally conductive matrices as the carriers. In the end, it is pointed out that the types of MOFs and phase-change materials used in MOF-based composite phase-change materials, the influence of the interaction between MOFs and phase-change materials on the heat storage performance, and the stability of MOFs after compounded with phase-change materials needed further exploration in the future. Besides, developing multifunctional materials by combining the catalytic and detection functions of MOFs with the heat storage and temperature control functions of phase-change materials was also one of the future development directions.

Key words: latent heat storage, phase change, metal organic frameworks (MOFs), composites, heat conduction, surface modification

摘要：

固-液相变材料的品种多且潜热大，是潜热储热技术的重要工作介质。因其存在的液相泄漏问题，现阶段常将此类相变材料与多孔载体复合以提升相变材料的应用性能及使用寿命。金属有机骨架（MOFs）是一种新型多孔材料，具有高比表面积、高孔隙率以及孔径和表面性质可调控等优势，将其用作相变材料的载体具有潜在的发展前景。本文对MOF基复合相变材料的研究进行了全面综述，详细介绍了以MOFs为载体、以MOFs衍生多孔碳为载体和以MOFs原位生长于高导热基体所得复合材料为载体而制得的多种复合相变材料。MOFs的微孔结构所产生的强毛细管力对固-液相变材料有很强的固定作用；制备较大孔径的MOFs或者对MOFs进行修饰以调节MOF与相变材料间的相互作用，都有利于提高相变材料的负载率，从而提升复合相变材料的潜热；对MOFs进行高温碳化处理得到MOFs衍生多孔碳能有效解决MOFs孔径过小的问题，并能通过对其进行氮掺杂或磷掺杂来增强载体与相变材料间的氢键作用，从而获得具有高负载率和相变潜热的复合相变材料；为了增强MOF基复合相变材料的导热性能，先将MOFs原位合成在高导热基体上以利用高导热基体提供连续的传热网络，可以有效提升复合相变材料的导热系数。将原位生长在高导热基体上的MOFs进行高温碳化处理可以得到MOFs衍生多孔碳与高导热基体的复合材料，将其作为载体可以进一步增强复合相变材料的导热性能。文中最后指出，今后对于MOF基复合相变储热材料所用MOFs和相变材料的种类、MOFs与相变材料间相互作用对储热性能的影响、MOFs与相变材料复合后的稳定性等方面还需进一步探索，将MOFs的催化、检测等功能与相变材料的储热控温功能相结合制备多功能材料也是未来的发展方向之一。

关键词: 潜热储热, 相变, 金属有机骨架, 复合材料, 热传导, 表面修饰