Abstract:

Incorporation of graphene into sodium acetate trihydrate (SAT) is a common approach to enhance its thermal conductivity, but significant interfacial thermal resistance (ITR) is usually generated at the interface of composite phase change materials. Exploring the mechanism of interfacial thermal resistance formation and reduction methods were currently research hotspots. This study proposed a method to reduce the interface thermal resistance between SAT and graphene by introducing a copper layer. A molecular dynamics model of composite material was established and the properties of the composite material were analyzed in terms of thermal conductivity, thermal resistance, radial distribution function (RDF), mean square displacement (MSD), diffusion coefficient and phonon density of states (PDOS). The results demonstrated that the ITR in the composite materials was mainly caused by the reduction in low-frequency phonons and the increase of phonon scattering caused by a more disordered phonon distribution. The copper layer mitigated phonon disorder in the graphene/SAT composite, thereby reducing ITR and enhancing thermal conductivity. The present study can provide theoretical support for experimental analysis and guidance for decreasing the interfacial thermal resistance of composite materials and preparing high thermal conductivity composite materials.

Key words: molecular simulation, composites, interface, sodium acetate trihydrate, graphene, interfacial thermal resistance, phonon density of states

摘要：

在三水醋酸钠（SAT）中添加石墨烯是提高其热导率的常用手段，但复合相变材料的界面处通常会产生较大的界面热阻，探究界面热阻形成机理和消减方法是当前研究热点。本研究提出利用铜层降低SAT/石墨烯界面热阻方法，利用分子动力学建立复合材料模型，从热导率和热阻、径向分布函数（RDF）、均方位移（MSD）和扩散系数、声子态密度（PDOS）等方面分析复合材料的性质。计算结果表明，复合相变材料界面热阻的产生是由于低频声子占比减小，且声子分布更加紊乱，增加了声子散射；铜层能降低石墨烯/SAT复合材料声子的紊乱程度，从而减小界面热阻，增强材料导热性能。本研究可为实验分析提供理论支撑，对降低复合材料界面热阻、制备高导热复合材料有指导意义。

关键词: 分子模拟, 复合材料, 界面, 三水醋酸钠, 石墨烯, 界面热阻, 声子态密度