石墨微粉膨胀插层制备介孔碳/石墨烯复合体及氮硫化对其超电性能提高的作用机制

We intend to design and prepare the nitrogen and sulfur co-doping mesoporous carbon/graphene composites, which are applied for the supercapacitor electrode materials. In our work, the graphite powder is selected as carbon sources. Under the vacuum, we infuse the polymer monomer solution into the interlayer of expanded graphite. Then, nitrogen and sulfur co-doping mesoporous carbon/graphene composites are produced by the hydrothermal means and high thermal ammonia treatment process. The mesoporous carbon structure is in favor of the transmission and diffusion of reactant and products. The graphene can not only enhance the electrode material conductivity, but also can improve the stability of mesoporous carbon materials. Meanwhile, nitrogen and sulfur co-doping can further improve the pseudocapacitance property and electrochemical activity. The changes of surface chemical environment and valence state could be investigated by the X-ray absorption spectroscopy. The further investigation about the interaction within the electrode material components is need by the theoretical calculation and electrochemical measurement. moreover, we should understand the mass transfer and diffusion process in the mesoporous structure.The content and style of nitrogen and sulfur element within composite are studied for understanding the improvement of energy storage performance. We want to expound the relationship between the structure and the property, in order to promote the application of similar materials in energy storage field.

本项研究拟制备介孔碳/石墨烯的氮硫化复合电极材料应用于超级电容器领域。首先利用石墨微粉制备高硫膨胀石墨，采用真空辅助压力诱导、原位插层方法使聚合物单体原位插层高硫膨胀石墨层间，利用聚合物单体在膨胀石墨层间原位聚合力使膨胀石墨剥离，再经后续氮化处理，制得氮硫化介孔碳/石墨烯超级电容器电极材料。在上述复合材料中，介孔碳结构有利于传质与扩散，提高超级电容器比电容和能量密度；石墨烯有利于提高电子传输能力及介孔结构稳定性的提高；而电极材料的氮硫化进一步提高赝电容特性以及电化学活性。利用X射线吸收谱实时监测反应过程中电极材料表面化学环境、价态的变化；理论计算结合电化学测试结果，对超级电容器电极材料组分间相互作用以及储能特性进行研究；深入理解介孔结构中传质、扩散等电极过程本质，揭示电极材料氮硫共掺杂对超电储能特性提高的内在作用机制，为这类电极材料的合成提供坚实的理论和实验依据。

利用电化学能量存储与转化的超级电容器表现出充放电速度快、环境友好以及超长的循环寿命等优点，己经成为备受关注的研究热点之一，而影响超级电容器性能最核心因素是电极材料的性能。本项研究提出制备不同结构碳材料（二维石墨烯，多孔碳，生物质碳等）及碳基复合电极材料，首先，以廉价并且导电性能良好的膨胀石墨或石墨烯为基础，采用真空辅助压力诱导、原位插层、后续热处理等技术，制得石墨或石墨烯为基底的三维复合电极材料。石墨烯与多孔碳的有效结合促进各组分协同效应的发挥，石墨烯的引入不仅提高了复合结构的导电性，多孔碳结构的存在促进电荷快速传输以及电解液离子有效扩散，多孔碳与石墨烯的有效结合显著提高容量、倍率特性和循环稳定性。此外，从廉价易得的生物质出发，获得生物质碳电极材料，具有多孔结构的生物质碳有利于提高超级电容器比电容和能量密度；而客体材料的负载又进一步提高赝电容特性以及电化学活性。利用电化学测试技术表征电极材料表面化学环境、价态的变化，揭示超级电容器电极材料组分间相互作用以及储能特性的内在原理，理论计算结合实验表征，探讨材料结构及界面耦合作用对其性能的影响规律。阐明能量转化过程电解液分子及电子在电极内部的传质、扩散等电极过程的本质，为这类电极材料的合成提供坚实的理论和可行的技术路线。