如何实现高效的热管理已经成为电子设备、能量转化与存储等器件发展中亟需解决的问题之一，这已成为业界共识。例如，手机、笔记本等移动电子设备日趋小型化与多功能化，使得功率密度增高，热负载增大，过高的温度将严重影响电子设备的运行速度和稳定性。自1991年碳纳米管被Iijima发现以来，碳纳米管优异的热学性质受到了人们的广泛关注与深入研究，此外，鉴于碳纳米管优异的化学稳定性和力学性能，碳纳米管材料被认为在热管理方面具有很高的研究及应用价值。How to achieve efficient thermal management has become one of the urgent problems to be solved in the development of electronics, energy conversion and storage devices, and this has become the industry consensus. For example, portable electronics such as mobile phones and laptops become increasingly compact and multifunctional, which leads to high power density and heat load. The excessive temperature will seriously affect the operating speed and the reliability of electronics. Since Carbon nanotubes (CNTs) were discovered by Iijima in 1991, their excellent thermal properties have received lots of attention and in-depth research. Due to the remarkable chemical stability and mechanical properties, CNT materials are considered to possess significant research and application values. 清华大学物理系、清华-富士康纳米科技研究中心研究团队发表综述文章，系统性地概述了碳纳米管材料在热管理方面的研究进展。该综述文章以单根碳纳米管的热学性质为出发点，介绍了碳纳米管基复合材料热导率的增强性能。详细分析与总结了顺排碳纳米管材料（顺排碳纳米管阵列、薄膜/巴基纸、纤维）的热导率大小及碳纳米管材料与基底间的接触热阻。展示了目前碳纳米管材料在被动散热（热辐射、自然对流以及相变散热）方面的研究进展。The research team of Department of Physics of Tsinghua University and Tsinghua-Foxconn Nanotechnology Research Center published a review article summarizing the progress of CNT-based materials in thermal management. This review article takes the thermal properties of a single CNT as a starting point, and then describes the progress of thermal conductivity of CNT-reinforced composites, aligned CNT materials (aligned CNT arrays, films/buckypapers, and fibers) as high thermal conductors, experimental and theoretical results of CNT-substrate interface resistance, and utilizations of CNTs in the passive heat dissipation (natural convection, heat radiation, and phase-change heat transfer).
Fig.1 The applications of CNT-based materials in thermal management
Fig.2 The high emissivity of CNT arrays and their applications in heat radiationFig.3 Natural convection heat transfer of CNT-based materials
Fig.4 The applications of CNT-based materials in the phase-change heat dissipation最后，通过对现有研究的综合阐述，本文针对碳纳米管材料在热管理中的研究方向以及发展趋势提出了几点看法：通过提高碳纳米管的质量并在增加其在复合材料中体积分数的同时维持碳纳米管较高的取向性，有望进一步提高碳纳米管复合材料尤其是热界面材料的热导率；仍需大量实验研究来进一步降低碳纳米管材料与基底间的接触热阻，完善碳纳米管与不同材料（金属、有机材料）间的接触热阻的理论解释及计算；碳纳米管材料的被动散热能力仍需进一步提高并且存在一定挑战，例如如何设计碳纳米管基吸液芯的结构以同时提供高毛细力和渗透率，如何实现碳纳米管基材料自然对流、热辐射以及相变散热的最佳结合等。本文希望通过对现有研究的概述与分析，进一步推动碳纳米管材料在热管理方面的研究与应用。Finally, based on the results reviewed here, we put some perspectives on CNT-based thermal management systems: (i) further thermal conductivity enhancements of CNT composites are promising in the future by simultaneously achieving the merits of large volume fraction, high CNT quality, and perfect CNT alignment in the composites; (ii) experimental studies on how to further decrease CNT-substrate interfaical thermal resistance (ITR) and theoretical works on ITR between CNTs and other substrates like metal and polymer are necessary to be done in the future; (iii) there remain several challenges in achieving better passive heat dissipation performance such as obtaining unique CNT wick structure to simultaneously provide high capillary pressure and large permeability, and how to achieve the best combination of natural convection, heat radiation and phase-change heat dissipation of CNT-based materials.Yu, W., Liu, C. & Fan, S. Advances of CNT-based systems in thermal management. Nano Res. (2021).DOI：10.1007/s12274-020-3255-1https://doi.org/10.1007/s12274-020-3255-1清华-富士康纳米科技研究中心坐落于清华大学校园内。中心大楼于2003年建成，建筑面积13000平米，拥有高等级的超净实验室、先进的微纳米制备和测试设备以及多个高水平的研究团队和宽松融洽的学术氛围。中心在范守善院士领导下，开展具备重要科学技术意义和产业应用前景的纳米科技研究，已取得多项拥有自主产权的科研成果。其中热传导研究组长期致力于纳米材料热传导基础与应用研究，目前已在Advanced Materials，Nano Letters, ACS Nano, Nano Energy等杂志发表论文100多篇，获得专利授权20多项。Tsinghua-Foxconn Nanotechnology Research Center is located on the campus of Tsinghua University. The center with a building area of 13,000 m2 was completed in 2003, possessing high-level ultra-clean laboratories, advanced micro and nano preparation and testing equipment, multiple high-level research teams, and a relaxed and harmonious academic atmosphere. Under the leadership of Academician Shoushan Fan, the center has carried out nanotechnology research with scientific and technological significance and industrial application prospects and has achieved many scientific research results with independent property rights. Among them, heat conduction research group has focused on the fundamental and applied research on heat transfer properties of nanomaterials. The group has published more than 100 papers in Advanced Materials, Nano Letters, ACS Nano, Nano Energy and, etc., and obtained more than 20 patents.