锂电金属极片/石墨烯界面共轭π键的构建及其热传导机制研究

High-performance lithium-ion batteries require more stringent heat dissipation. Conducting heat through the electrodes is a feasible way to improve the heat-dissipating of the battery system. Graphene has an excellent thermal conductivity and electron mobility. However, the metal / graphene formed by simple composite has poor heat dissipation capability. Conjugated π-bond is formed by the interface between graphene and metals due to the ultra-high electron mobility of graphene, in which the bridge is built for delocalized electron. At the same time, electron is being brought into full play on heat-conduction between graphene and metals and the thermal conductivity is improved. Through the implementation of this project, the effect of the construction of π-bond on heat conduction by the interface between graphene and metals is clarified, the effect law between the flow direction of electron and the interface heat conduction is revealed, and a new theoretical basis for the application of graphene on the interface heat conduction of composite is provided, which ultimately promotes the application and development of graphene in the field of heat conduction. In addition, the implementation of this project opens up a new direction for the heat dissipation of graphene in the lithium-ion battery system. Meanwhile, the problem of thermal resistance of graphene / metal interface is solved, which can be used as reference for solving similar problems of composite.

高性能锂离子电池对散热提出越来越高的要求。通过正负金属极片进行散热是提高电池系统散热的可选方法。石墨烯具有极高的导热能力，然而，依靠简单的复合形成的金属/石墨烯的散热能力很低。项目通过有机共轭小分子化合物的桥接，在石墨烯和金属界面间构建共轭π键，为π电子在石墨烯和金属间建立桥梁通道，发挥电子在石墨烯/金属极片间界面热传导的作用，提高石墨烯/金属复合物的界面热传导和电传导性能。通过改变共轭小分子基团性质，达到对π电子传输过程的调控，影响其热传导和电传导机制。通过本项目的实施，阐明共轭π键的建立对石墨烯/金属极片界面热传导和电传导的影响机制，揭示共轭π电子的传输过程对石墨烯/金属极片界面热传导和电导率之间的影响规律，为石墨烯在复合材料界面热传导和电传导领域的应用奠定理论基础，为石墨烯在锂离子电池系统的散热开辟一个新的方向。通过石墨烯/金属界面热阻问题的解决，为复合材料同类问题的解决提供借鉴。

高性能电子器件对散热提出越来越高的要求。通过对发热体的表面进行涂覆导热材料是电子器件散热的可选方法。石墨烯具有极高的导热能力，然而，依靠简单的复合形成的金属/石墨烯的散热能力很低。项目通过有机共轭小分子化合物的桥接，在石墨烯和金属界面间构建共轭π键和σ键。共轭π键的构建为π电子在石墨烯和金属间建立桥梁通道，发挥π电子在石墨烯/金属极片间界面热传导的作用；σ键的构建为声子在石墨烯和金属之间建立桥梁通道，促进声子的热传导作用。通过同时发挥声子和电子在石墨烯和金属之间的作用，共同提高Cu/石墨烯复合材料的导热性能。.我们分别通过乙炔苯胺、苯硫酚和苯胺对石墨烯进行功能化，在石墨烯和Cu之间构建共轭π键，在σ键的基础上发挥π电子的热传导作用。100℃时，乙炔苯胺改性石墨烯/Cu复合材料的导热系数为497 W·m-1·K-1，分别比Cu基体和未改性的材料高1.61倍和1.3倍。苯硫酚改性石墨烯/Cu复合材料的导热系数为500.6 W·m-1·K-1，比Cu基体提高42.6%。苯胺改性石墨烯/Cu复合材料的导热系数达到506W·m-1·K-1，分别比Cu基体和未改性材料高44.2%和30.8%。在此基础上，我们利用吸电子的苯甲酸分子和供电子的苯酚分子改变石墨烯的电子结构。BA-Gr/Cu复合材料和PH-Gr/Cu复合材料的导热系数分别达到453W·m-1·K-1和508W·m-1·K-1。与此同时，我们采用硅烷偶联剂在Cu和氧化石墨烯之间构建共价键(Cu-O-Si-O-C)，以降低热阻和减弱界面的声子散射。所得材料在50℃和150℃时的导热系数分别达到415.2和361.9 W·m-1·K-1。