大倍率高能量密度双电层电容器用煤系层次孔炭电极的研究

For a practical improvement of supercapacitor energy density as well as rate capacity, further researches are suggested hereby starting from elaborate structure construction. Considering of material surface wettability and feasible energy usage estimated on a whole synthesis route comparing with those from graphene, coal tar pitch-derived material were particularly chosen to be precursors because they are composed of polycyclic aromatic hydrocarbons (PAHs) with wide size distribution, similarly to graphene in chemistry. Using non-template method, hierarchical graphitic nanoporous carbon with a rough surface is suggested to be synthesized. Different ways are supposed to take in charge of the creation of pores in a different range. For the sake of reasonable electrical conductivity necessary for high energy density, surface defects are to be lessened by deactivation of a selected function group. Also, thermodynamic factors are supplementary for surface defective structure control. More efforts are intended to make on the relationship of electrochemical performances with such special structure containing shallow micropores, mesopores and macropores fabricated by the aid of amphipathic property of water-dispensible carbons, herein refered as the basic building block of nanoporous carbon as electrode material. Chemistry and structure of coal-derived precursor are important in the formation of carbonaceous electrode material and thereof electrochemical performance as an electrode in a supercapacitor. Breaking and formation of conjugated sp2 C-C bonds(basal plane) or sp2 C-H bond (edge) are important in this chemistry and thus need to be emphasized on. All the attempts are applicable to the nanoporous carbon related field, especially design, controllable synthesis, and functionalization of porous carbon.

为了进一步提高双电层电容器的能量密度，必须对电极材料的结构进行设计和优化。本项目将选择富含各种尺度的稠环芳烃的煤系衍生物为原料，采用非模板法，提出了"三种孔径三种构建"方式，可控合成具有"浅微孔型层次结构"的层次孔炭电极材料，组装具有大倍率和高能量密度的双电层电容器。系统研究基于官能团保护机理的材料表面缺陷控制机制以及热动力条件下的缺陷修复；探讨两亲性多孔炭材料中浅微孔、中孔、大孔的构建与调变机制，阐明材料的结构及其调变与高能量密度和大倍率特性之间的构效关系，考察"浅微孔型层次结构"在高能量密度和大倍率储能二者兼备方面的优势；探讨在构建高比表面多孔结构的过程中，煤系原料自身的化学、结构特性与所得多孔炭的表面缺陷（非sp2 杂化结构）、粗糙特征之间的内在联系。本项目将为高性能储能用多孔炭材料的结构设计、可控制备和功能化调控提供理论支持和依据。

针对双电层电容器的短板--能量密度，围绕合理设计多孔炭电极材料的结构开展了系列的研究工作。选择富含稠环芳烃的煤系衍生物为原料，采用非模板法，提出了“三种孔径三种构建”方式，可控合成具有“浅微孔型层次结构”的层次孔炭电极材料，获得了大倍率EDLC性能和可与石墨烯类材料匹敌的高能量密度。内容主要包括：（1）采用化学复合的方法构建具有“浅微孔层次结构”的三维立体多孔C/C复合材料，兼顾高导电（连续完美的六元环炭网络）与全生命周期内的高性能（梯级多孔特性）；（2）形成高导电纳米多孔C/C复合材料的制备工艺技术，保证材料本身具备足够高的导电率，将传统电极中的（炭+粘结剂+导电剂）三元固固界面简化为（C/C复合物+粘结剂）两元固固界面，促进全寿命周期内储能性能的稳定发挥；（3）提高炭材料中的sp2杂化碳原子比例并减少表面官能团，构建了高耐电压多孔C/C复合材料，在TEABF4/PC电解液（3 V耐受电压）和离子液体EMIMBF4电解液（3.5 V耐受电压）中获得了出色的EDLC电化学性能；（4）采用富含稠环芳烃的煤系两亲性炭材料构建了二维纳米炭片，并组装了多孔炭材料，在离子液体EMIMBF4电解液中20 A g-1电流密度下质量比电容高达157.8 F g-1，倍率特性C20/0.05高达86.7%，同时在超大功率密度下（17.5 kW kg-1）其能量密度仍能达到67.1 Wh kg-1。本项目深入探讨了多孔炭材料中浅微孔、中孔、大孔的构建与调变机制，阐明了材料的结构及其调变与高能量密度和大倍率特性之间的构效关系，考察了“浅微孔型层次结构”在高能量密度和大倍率储能二者兼备方面的优势，并探讨了在构建高比表面多孔结构的过程中煤系原料自身的化学、结构特性与所得多孔炭的表面缺陷之间的内在联系，为高性能储能用多孔炭材料的结构设计、可控制备和功能化调控提供理论支持和依据。