电纺纳米碳纤维的结构控制、掺杂改性及其超级电容性能

Electrospun carbon nanofibers (ESCNFs) are suitable for the application of supercapacitors due to the material form of free-standing membrane, small diameter, and absence of agglomeration. However, good supercapacitive performance has not been attained currently for the conventional ESCNFs because of their low specific surface area. This project attempts to improve the supercapacitive performance of the ESCNFs greatly by the structure control and modification through doping. NH3 is applied during carbonization to decrease the diameter of the ESCNFs due to its etching reactivity with carbon. Growth of the graphene-like structure is caused by the carbon-containing active radicles generated from the reaction of NH3 with carbon during carbonization, which will be enhanced by introducing appropriate amount of CH4. Doping modification of the ESCNFs is carried out by selecting appropriate precursor and subsequent surface treatment. The specific surface area of the ESCNFs will increase with the decrease of their diameter. The exposure of the graphene edges will greatly increase the ability to attract ions. Doping generates additional pseudocapacitance, promotes ion adsorption, and improve the wettability. It is expected that the supercapacitive performance of the ESCNFs will be imcreased greatly by the combined effects of the above factors. The mechanism of doping modification and structure control of the ESCNFs will be revealed and their process will be established. The ESCNFs with high supercapacitive performance will be obtained by this research.

电纺纳米碳纤维（ESCNFs）具有优越的自支撑膜形式，直径细小，不会团聚，适于超级电容器应用。但由于常规ESCNFs比表面积小，目前尚未获得良好的超级电容性能。本项目研究通过ESCNFs的结构控制和掺杂改性实现其超级电容性能的大幅度提高。利用NH3对碳的刻蚀反应性通过在NH3中碳化前躯体纤维实现其直径的减小；碳化过程中NH3与碳反应产生的含碳活性基团导致类石墨烯结构在纤维表面生长，通过引入适量CH4可以强化这种类石墨烯的生长。通过选用合适的前躯体及后续处理实现ESCNFs的掺杂改性。直径的减小增加比表面积；裸露于表面的类石墨烯边缘可以大大提高离子的吸附能力；掺杂产生额外赝电容，并促进离子的吸附及改善润湿性。通过以上各因素的共同作用可望大幅度提高ESCNFs的超级电容性能。本项目将揭示ESCNFs掺杂改性和结构控制的机制并建立其工艺，获得高性能ESCNFs超级电容器电极材料。

本项目研究电纺纳米碳纤维的结构控制、掺杂改性及其超级电容性能，根据申请书提出的研究计划开展了研究工作，实现了预定的研究目标，取得了较大的研究成果。研究了电纺纳米碳纤维的制备，建立了超细电纺纳米碳纤维的可控制备工艺，制备出平均直径11nm的纳米碳纤维，在纳米碳纤维表面生长了石墨烯结构，并揭示了其生长机制。研究了纳米碳纤维的掺杂，测定了使用不同的氮源、氮源浓度和碳化温度对掺杂氮的浓度和类型的影响，获得了氮掺杂的优化工艺。建立了一种对纳米碳纤维表面进行功能化处理的电化学方法，发现电化学处理可以有效实现表面功能化，提高电化学性质。在纳米碳纤维表面生长了MnO2活性材料，在双电层电容的基础上复合了赝电容，有效提高了纳米碳纤维的性能。测定了超级电容性能，研究了纤维结构与超级电容性能的关系，包括纤维直径、表面石墨烯结构、掺杂浓度、掺杂类型及表面功能化对超级电容性能的影响，获得了超级电容性能的控制工艺，超级电容器能量密度最高达到29.1 Wh/kg。基于纳米碳纤维的二氧化锰纳米纤维所制备的超级电容器能量密度达到41.1Wh/kg。本项目所取得的多项性能指标处于本领域先进水平。本项目一共发表SCI收录论文14篇，申请专利4项。毕业博士生3名，硕士生2名。