碳纳米纤维耦合石墨-膨润土基复合相变材料的构筑与储热性能协同强化

Mineral-based phase change composites is an important research direction of preparation of high performance solar thermal storage materials with low cost. It is still a main difficulty in developing advanced mineral-based phase change composites to attain simultaneously enhanced thermal conductivity and energy storage capacity. Aiming at preparation of high performance mineral-based phase change composites, the aligned carbon nanofibers are in-situ growthed on the surface of flake graphite by chemical vapor deposition, and the bentonite will be bonded to the top of carbon nanofibers. The bentonite and flake graphite are coupled by carbon nanofibers. And then, the supports with obvious thermal storage characteristics will be synthesised. The phase change materials are loaded to support and phase change composites based on coupled graphite-bentonite by carbon nanofiber will be constructed. The strengthening interfacial coupling of carbon nanofibers with mineral will be realized by analysis interfacial characteristics. Effects of supports on phase transition behaviour of phase change materials will be explored by characterizing structure and performance, and relationship between structure and property will be expressed. The synergistic strengthening mechanism of thermal storage capacity and thermal conductivity by carbon fiber will be revealed on microstructural-level. In this research, one-dimensional carbon nanofibers is used to enhance thermal storage characteristics of two-dimensional mineral, and three-dimensional net structure with dual function of thermal transfer path and storage space will be obtained. It is hopeful to significantly enhanced thermal conductivity and energy storage capacity. This project attempting to offers us a new way to explore manufacturing technology and theoretical basis for high performance solar thermal storage materials.

矿物基复合相变材料是低成本、高效太阳能储热材料的重要研究方向，大幅度同时提高其储热容量与导热系数是目前的主要难点。本项目采用化学气相沉积法在鳞片石墨表面原位定向生长碳纳米纤维，通过化学键合将膨润土结合至碳纳米纤维顶端，耦合石墨与膨润土，合成储热特征明显的支撑基体，再装载相变功能体，构筑碳纳米纤维耦合石墨-膨润土基复合相变材料；分析界面特征，阐明碳纳米纤维与膨润土界面强化耦合机理；表征结构与性能，探究支撑基体对相变功能体相变行为的影响，明确构性关系；从微结构层面揭示碳纳米纤维对储热容量与导热系数协同强化的机制。本项目利用一维碳纳米纤维增强二维矿物的储热特征形成三维网络结构，可实现传热通道和储存空间的双重功能，有望大幅度同时提高储热容量与导热系数，以期为高效太阳能储热材料的制备提供新思路和理论基础。

矿物基复合相变材料是低成本、高效太阳能储热材料的重要研究方向，大幅度同时提高其储热容量与导热系数是目前的主要难点。本项目对天然鳞片石墨表面改性、层间剥离并考察其对储热性能的影响；采用化学气相沉积法在鳞片石墨表面生长碳纳米纤维，通过化学键合将改性膨润土结合至碳纳米纤维顶端，耦合石墨与膨润土，合成储热特征明显的支撑基体，再装载相变功能体，构筑矿物耦合基复合相变储热材料。通过以上研究，提出了石墨表面改性强化储热性能的新方法，改性后基体表面含氧官能团增多，与相变功能体之间能够形成稳定桥连；揭示了石墨层间剥离强化储热性能的机制，通过研究层间剥离程度对储热性能的影响，验证得到石墨剥离程度越高、装载容量越大，从而建立了剥离层厚与复合材料储热性能之间的关系；实现了碳纳米纤维耦合石墨和膨润土，合成了储热特征明显的矿物耦合支撑基体，形成的三维网状结构为相变功能体提供更多存储空间，耦合行为能够减少界面热阻，矿物耦合基体的导热系数为4.595 W m-1 K-1，阐明了界面耦合强化机理；利用矿物耦合支撑基体装载相变功能体构筑了高效矿物耦合基复合相变储热材料，实现了储热性能协同提升，揭示了碳纳米纤维对储热容量与导热系数协同强化的机制。本项目挖掘了并提升了矿物的储热特征，阐明了石墨表面、层间、界面与储热性能之间的关系，实现了储热性能的调控与强化，丰富了储热矿物材料研究体系，为高效储热材料的制备提供了新思路和理论基础。