基于液相氧化策略的煤基二维纳米炭片构筑及其超级电容器性能研究

As an abundant mineral resource, coal has been used in many crucial fields such as energy, chemical engineering, and materials production. However, the traditional coal utilization ways are not only with high energy cost and low value-addition, but also with serious environmental pollution and resource waste. Thus, these ways are not in accordance with the strategy of sustainable development. Aiming at the clean and high value-added utilization of coal resource, in this project, we proposed a simple approach for design and preparation of coal-based advanced supercapacitor electrode materials based on liquid phase oxidation strategy. The aromatic building blocks in the coal will be effectively separated by means of depolymerization of the coal macromolecules using oxidation. Several coal-based two-dimensional carbon nanosheets will be then prepared by "bottom-up" re-assembly using the separated aromatic building blocks. By designing and adjusting the microstructure, pore-size distribution, chemical composition, crystallinity, and surface properties, it will be as far as possible to improve the gravimetric/volumetric capacitance, rate performance, and cyclic stability of the coal-based two-dimensional carbon nanosheets. The relationship between coal precursors, the liquid phase oxidation routes, the physicochemical properties of the products and their electrochemical performance will be put forward. Our results will provide a new and simple strategy for the design and preparation of advanced coal-based energy storage materials, and promote the clean and effective utilization of coal resources.

煤炭资源储量丰富且廉价易得，已被广泛应用于能源、化工、材料等关键领域。但是传统的煤炭使用方式不仅能耗高、经济附加值低，且污染和浪费严重，不符合国家可持续发展的战略要求。申请课题面向煤炭资源的高附加值清洁利用，开展基于液相氧化剪切策略的煤基高性能超级电容器电极材料制备研究。拟通过对煤炭大分子结构的液相氧化剪切，使其高度交联结构解聚，分离提取共轭稠环芳烃结构基元，并依据“自下而上”定向组装构筑的思路，对煤炭大分子的微观结构进行重构，通过对产物微纳结构、孔道分布、共轭程度、缺陷密度、表面状态的调控，制备一系列具有高质量/体积比容量、优异倍率性能和循环稳定性的煤基二维纳米炭片。揭示煤炭前驱体性质及液相氧化途径与产物物性及其储能性能之间的内在联系，开发煤基二维炭材料的设计和构建新策略，丰富发展煤基电化学储能材料的设计和应用内涵。

煤炭资源储量丰富且廉价易得，已被广泛应用于能源、化工、材料等关键领域。但是传统的煤炭使用方式不仅能耗高、经济附加值低，且污染和浪费严重，不符合国家可持续发展的战略要求。本项目以煤炭资源高附加值利用和煤基先进炭材料研发为目标，开展了基于液相氧化剪切策略的煤基功能性炭材料的结构设计和电化学储能应用研究。通过液相氧化使煤炭大分子解聚，成功分离煤炭结构基元——煤基石墨烯量子点和超小纳米炭片。明晰了煤炭前驱体性质与液相氧化方法对产物性质的影响规律。通过工艺优化，实现了煤基石墨烯量子点的克量级制备。首次提出“破而后立”的结构设计理念，以煤基石墨烯量子点为结构基元，通过“自下而上”模板诱导组装方法制备了煤基层次化纳米炭片和硼氮共掺杂纳米炭片，打通了煤炭大分子微纳结构可控设计的路径。为解决炭材料用于超级电容器时体积性能不佳这一关键问题，提出贯通超微孔结构设计思路，通过机械压实和整体活化，平衡了大比表面积和高密度之间的矛盾竞争关系，获得了兼具高质量/体积/面比容量、优异倍率性能和循环稳定性的超微孔炭。为了进一步开拓炭材料在致密储能方面的设计思路，通过简单球磨策略制备了一系列缺陷石墨烯组装体，发现炭材料的本征缺陷结构也是高效电容储能位点，明晰了其电容储能行为和机理。进而将炭材料的缺陷储能扩展至电化学储钠中，获得了综合性能优异的钠离子电容器负极材料。利用煤基石墨烯量子点的丰富边缘官能团和高结晶的内核，在活性炭内部构筑整体导电网络，显著提升了其储能容量和电化学动力学性质。进而提出整体力/电双增强网络的构建策略，获得了具有高比表面积、高机械强度、高柔性、高导电性的“四高”炭纤维织物。本项目的实施，提出了“破而后立”的设计新思路，打通了液相氧化和“自下而上”定向构筑的软化学策略，为煤炭资源的有效利用提供新的思路，也为高性能超级电容器炭基电极材料的设计提供了理论支撑。