物理化学学报 >> 2025, Vol. 41 >> Issue (3): 100025.doi: 10.3866/PKU.WHXB202404024

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石墨烯厚膜热扩散系数与微观结构的关系

白天琦1,2,†, 黄坤3,4,†, 刘法辰1,2, 时若晨1,5, 任文才3,4, 裴嵩峰3,4,*(), 高鹏1,2,5,6,7,8,*(), 刘忠范6,9,*()   

  1. 1 北京大学物理学院, 电子显微镜实验室, 北京 100871
    2 北京大学前沿交叉学科研究院, 北京 100871
    3 中国科学院金属研究所, 沈阳材料科学国家研究中心, 沈阳 110016
    4 中国科学技术大学材料科学与工程学院, 沈阳 110016
    5 北京大学量子材料科学中心, 北京 100871
    6 北京石墨烯研究院, 北京 100095
    7 量子物质科学协同创新中心, 北京 100871
    8 北京大学轻元素量子材料交叉平台和轻元素先进材料研究中心, 北京 100871
    9 北京大学化学与分子工程学院, 分子科学国家研究中心, 北京 100871
  • 收稿日期:2024-04-17 修回日期:2024-06-13 录用日期:2024-06-17 发布日期:2024-12-14
  • 通讯作者: Email: pgao@pku.edu.cn (高鹏)sfpei@imr.ac.cn (裴嵩峰)zfliu@pku.edu.cn (刘忠范)
  • 作者简介:

    †These authors contributed equally to this work.

  • 基金资助:
    国家自然科学基金(T2188101); 国家自然科学基金(52125307); 国家自然科学基金(52021006); 国家自然科学基金(52273240)

Nanoscale Mechanism of Microstructure-Dependent Thermal Diffusivity in Thick Graphene Sheets

Tianqi Bai1,2, Kun Huang3,4, Fachen Liu1,2, Ruochen Shi1,5, Wencai Ren3,4, Songfeng Pei3,4,*(), Peng Gao1,2,5,6,7,8,*(), Zhongfan Liu6,9,*()   

  1. 1 Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
    2 Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
    3 Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
    4 School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China
    5 International Center for Quantum Materials, Peking University, Beijing 100871, China
    6 Beijing Graphene Institute, Beijing 100095, China
    7 Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
    8 Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University, Beijing 100871, China
    9 National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
  • Received:2024-04-17 Revised:2024-06-13 Accepted:2024-06-17 Published:2024-12-14
  • Contact: Email: pgao@pku.edu.cn (Peng Gao)sfpei@imr.ac.cn (Songfeng Pei)zfliu@pku.edu.cn (Zhongfan Liu)
  • Supported by:
    the National Natural Science Foundation of China(T2188101); the National Natural Science Foundation of China(52125307); the National Natural Science Foundation of China(52021006); the National Natural Science Foundation of China(52273240)

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摘要：

电子元件集成度的快速提升对器件热管理提出了更高的要求。石墨烯凭借其出色的导热性能成为备受关注的材料之一。目前制备高热导率石墨烯厚膜的主流方法是将氧化石墨烯组装成膜再还原，尽管前人的研究取得了突出成效，但截止目前仍未能完全理解石墨烯膜内部缺陷结构对热导率的具体影响机制，这将限制热导率的进一步提升，达到或超过1500 W·m-1·K-1。在氧化石墨烯膜的热还原过程中，不可避免地会形成一些孔洞结构，通过降低整体密度的方式降低热导率。热扩散系数作为决定热导率大小的另一因素，孔洞对其影响因素却尚未被研究过。在这里，我们定义了包含孔洞的石墨烯膜材料特有的本征热扩散系数，并通过多种电子显微学方法、热扩散系数的测试和有限元模拟，详细研究了石墨烯厚膜的本征热扩散系数与微观结构之间的关联。我们旨在阐明孔洞对热扩散系数以及热导率的影响方式和作用机制。研究结果揭示了不同尺寸和数量的孔洞对热扩散系数的影响，发现密集小孔洞结构可使热扩散系数降低39.4%，而同等面积的单一大孔洞结构对热扩散系数的降低仅约16.1%。通过三维重构获得的统计结论也与计算结果完全匹配。其内在机制是密集小孔洞结构的存在对原有传热路径的破坏更为严重，而单一大孔洞结构的这一作用则相对较弱，只是降低了整体密度从而降低热导率。此外，研究发现面外结晶性对热扩散系数有显著影响，进一步增进了对影响热扩散系数的微观机理的认识。通过阐明这些机制，我们的研究加深了对石墨烯厚膜微观结构与热学性能关联的理解，为生产超高热导率的石墨烯厚膜提供了重要信息，也为下一代电子器件热管理解决方案提供了有效策略。

关键词: 石墨烯厚膜, 本征热扩散系数, 单一大孔洞, 密集小孔洞, 面外结晶性

Abstract:

The rapid advancement in the integration density of electronic components has led to a pressing need for effective thermal management solutions. Among the promising materials in this regard, graphene stands out due to its exceptional thermal conductivity properties. Currently, the production of ultra-high thermally conductive thick graphene sheets primarily involves the reduction of graphene oxide. However, despite significant progress, the impact of defects on thermal properties remains inadequately understood, limiting the achievement of thermal conductivity exceeding 1500 W·m-1·K-1. During the preparation process of reduced graphene oxide-based graphene sheets, hole structures are inevitably formed, reducing the overall density and thus decreasing thermal conductivity. However, the influencing factors on thermal diffusivity, one of the determining factors of thermal conductivity, have not been reported. Thus, we defined the intrinsic thermal diffusivity specific to materials with internal holes and further investigated the correlation between the intrinsic thermal diffusivity of thick graphene sheets and microstructure through various electron microscopy characterization, thermal diffusivity measurements, and simulations. We aim to elucidate the factors and mechanisms affecting the thermal diffusivity and hence thermal conductivity. Our research reveals subtle insights, particularly regarding the impact of holes of different sizes and quantities on thermal diffusivity. Notably, our simulation results show that a real dense-small-holes structure in graphene sheets can reduce thermal diffusivity by 39.4%, more than twice the reduction caused by a single-large-hole structure (16.1%). Statistical conclusions obtained through three-dimensional reconstruction also perfectly match these computational results. We emphasize that the presence of dense-small-holes structures disrupt the original high-speed heat transfer paths more severely, while the effect of single-large-hole structures are relatively weaker, primarily reducing overall density and thus thermal conductivity. Additionally, we found that the out-of-plane crystallinity has a significant impact on thermal diffusivity, further enhancing our understanding of microstructural factors affecting thermal diffusivity. By elucidating these mechanisms, our findings make significant contributions to the technological advancement of producing ultra-high thermally conductive thick graphene sheets. A deeper understanding of the interaction between microstructure and thermal performance brings hope for the development of next-generation electronic device thermal management solutions. Through continued research in this field, we anticipate further improvements in the performance and efficiency of graphene thermal management systems, ultimately driving innovation in electronic device design and manufacturing.

Key words: Thick graphene sheets, Intrinsic thermal diffusivity, Single large hole, Dense small holes, Out-of-plane crystallinity