碳基多级孔相变材料的多层次匹配组装与热特性强化

Phase change material (PCM) is a core factor in the development and application of energy storage technology, and it plays a crucial role in the exploring new energy sources and improving of energy utilization. Based on the research and development of hierarchical carbon-based phase change composites, this project puts forward an idea of multi-level synergistic and enhanced assembly design based on the matching effect of the hierarchical porous carrier- phase change core material, aiming to overcome the shortcoming that porous carriers cannot improve the phase change performance due to the single pore size structure. It is planned to start with the phase change process and the heat transfer performance where typical carbon-based micro/nano-porous matrix supports organic and inorganic core materials. The research is trying to explore size effect and rules of relevant thermal parameters, such as specific heat, thermal conductivity, latent heat, melting point. Moreover, the role of the coupling between the confined space size effect of micro/nano pores and the interfacial effect of carrier-core materials in the phase change heat transfer is obtained. Then the research will effectively extract match factor groups which have a significant effect on the phase change process and thermophysical properties, such as the topological structure of the carriers, the carrier-core interaction force and the modifiers outside the carriers. This study will achieve a rapid and directional design of hierarchical-pore carbon-based composite PCM with good loading, high energy storage density and high thermal conductivity.

相变材料是储能技术发展和应用的核心因素，在开发新能源、提高能源利用中起着至关重要的作用。本项目以研发多级孔碳基相变复合材料为出发点，针对现有多孔载体因孔径结构单一而无法进一步提升相变性能的现状，提出基于多级多孔载体-相变芯材匹配效应的多层次协同强化组装设计思路。拟以典型碳基微、纳多孔基体负载有机、无机芯材的相变过程和蓄传热性能为出发点，尝试探究比热、热导率、潜热、熔点等相关热物理参数的尺度效应及递变规律，获得微纳米孔受限空间效应和载体-芯材界面效应的耦合对相变蓄传热的作用机制，并有效提取载体拓扑结构、载体-芯材相互作用力及载体外加修饰基等参数中对相变过程、物性产生显著影响的匹配因子组，最终实现“固载性好、高储能密度以及高热导率”的多级孔碳基复合相变材料快速、定向设计。

本项目按照预期目标，从实验和模拟相结合的方法获得相变芯材在碳基纳米受限空间内的相变热输运机制及热物性，提出基于多级多孔载体-相变芯材匹配效应的多层次协同强化思路，最终构筑微纳米能源材料的实验制备-结构表征-热特性测试-微观模拟的研究体系，从而指导光-热-力学性能协同强化的多级孔碳基复合相变材料的匹配设计与可控制备。.通过研究，实现了碳基多孔骨架（介孔碳、多级孔碳HPC、膨胀石墨、石墨烯泡沫、金刚石泡沫）与普适中低温相变材料（聚乙二醇、赤藓糖醇、硝酸钠）的匹配组装、结构表征、物性测量及分子动力学模拟分析。探究了碳受限空间内聚合物的结晶行为，探讨了极性官能团对复合材料蓄传热特性调控的规律；阐明了多级孔道强化相变热特性的机制，明晰了多级孔骨架-芯材界面热输运机理；分析了不同种类及不同维度纳米颗粒掺杂下骨架-芯材-纳米颗粒复合体系的相变热特性；通过3ω测试平台和扫描热显微镜测量了复合材料的热导率，搭建了复合相变材料宏观蓄传热及光热转换的测试平台并进行循环蓄放热试验，验证并评估复合材料的实际应用性能。重要结论有：1）通过孔道表面修饰改性可改善骨架对芯材结晶相变的限制，芯材的负载量与官能团极性密切相关，而骨架与芯材间的相互作用不仅与材料本身及官能团的极性有关，还受孔径，孔体积等因素的影响。2）在多级孔骨架中，小孔的强界面作用能利于对芯材的吸附和束缚、大孔提供更大容积并缓解芯材的附壁不相变，通过化学模板衍生的多级孔碳复合材料的负载量及结晶率＞90%。3）结构-热一体化的碳纳米管与骨架通过范德华力作用形成二次网络，碳纳米管作为导热增强填料和定形骨架的功能兼收并蓄，复合材料热导率较纯芯材提升118%；而界面处形成化学键合可使界面热导提升高达30倍，由泡沫铜表面生长的金刚石泡沫复合材料的热导率较金属有机骨架衍生的多级孔碳复合材料提升一个量级（＞1W/m·K）。4）高导热纳米颗粒的引入能够使太阳光迅速通过骨架内部的三维热输运网络，大大提升复合相变材料的储热-光热转换效率（达90%）。本研究为设计一类革新性的快速响应-高导热-高存储密度的多级孔碳基复合相变材料提供指导。