高效锂空气电池用石墨烯/酞菁基MOFs复合空气电极的构建及其性能研究

In recent years, lithium-air battery has received increasing attention as a new battery system for its ultra-high energy density. Performance of porous electrodes is essential for lithium-air battery. However, there are still some problems for porous electrodes up to now, such as low catalytic efficiencies, small specific surface areas and pore clogging during charge/discharge process. Thus, they cannot meet the demand of practical applications. The project intends to assemble phthalocyanine compounds with excellent catalytic activities into metal organic frameworks (MOFs) with large specific surface, and further composited with graphene that has ultra-high conductivity, to build porous graphene/phthalocyanine-based MOFs composite electrodes for lithium-air battery. Two kinds of in-situ technologies will be used for preparing the composites. The molecular compositions, pore sizes and structures of the composites will be controlled to enhance their "bifunctional" catalytic efficiencies, and to further improve their electrochemical performance. The effect of the compositions and ratios of raw materials, the pH, and concentrations on the compositions, structures and morphologies of composites will be discussed. The catalytic activity and electrochemical performance of the composites will be analyzed to investigate the relationship between the compositions, structures and catalytic activities. The catalytic mechanism of the composites as porous electrodes will be systematically summarized. The project aims to explore facile and controllable ways for synthesizing graphene/phthalocyanine-based MOFs composites, to provide a theoretical basis for the design and development of new and efficient porous air electrodes, and to give new thoughts for the catalytic properties of MOFs.

锂空气电池是近年来广为关注的一种超高能量密度的新型电池体系。多孔电极的性能对锂空气电池至关重要。目前多孔电极存在催化效率低、比表面积较小、孔道易堵塞等问题，难以满足需求。本项目拟将具有良好催化活性的酞菁化合物组装到比表面积大的金属有机框架（MOFs）材料上，并与超高导电性的石墨烯复合，构筑多孔石墨烯/酞菁基MOFs复合材料，用于锂空气电池多孔电极。拟采用两种原位复合技术，通过调控其分子组成、孔径、孔结构等，提升其“双功能”催化效率，改善电池的性能。考察原料的组成、配比、pH值、浓度等对复合材料的组成、结构和形貌的影响；分析其催化活性及电化学性能表现，揭示组成、结构和催化活性之间的构效关系；探索其作为多孔阴极的催化机理。本课题旨在探索简易可控的合成石墨烯/酞菁基MOFs复合材料的技术路线，为设计和开发新型高效的多孔空气电极提供理论基础，同时为MOFs的催化研究提供新思路。

本项目以石墨烯基材料与MOF材料相结合为基础，探索了石墨烯基材料、MOFs基材料及两者复合材料作为电极在空气电池、锂离子电池、钠离子电池等储能领域的电化学反应机理，主要的结论如下：（1）首先采用石墨烯基MOF材料作为多孔电极进行了探索研究，通过调控试验参数如不同溶剂和比例、配位中心金属离子、配体等，改变MOF、酞菁化合物及石墨烯基材料的类型、形貌、尺寸，得出了材料类型、尺寸、形貌和电化学性能之间的构效关系；（2）利用MOFs自模板法获得具有多级多孔结构的过渡氧化物@碳复合材料，如Fe3O4@C、Co3O4@C-N、MnO@C-N和二维MnO@C等复合材料，对其进行了储锂性能研究，并探讨了不同MOFs结构、形貌、尺寸、反应条件对复合材料的结构、形貌、尺寸和电化学性能的影响机制。（3）合成具有电化学可逆性的MOF材料，并研究其储锂机制，探讨MOF的中心金属原子、配体的类型、结构及电化学活性位点和电化学特性参数如电压平台、比容量及循环稳定性等的构效关系，并得出其电化学反应机制。（4）以石墨烯基材料为基础，研究其作为钠离子、锂离子存储材料的可行性，并探讨电化学反应机理。通过调控其维度、形貌、尺寸并与其它半导体、有机多电子体、二维材料复合，研究其对钠离子的传输与迁移、界面电化学反应以及对钠离子存储/脱出的可逆反应速度的影响。本项目的实施对将MOFs发展为一种新型高效的储能材料提供一定的理论指导，为石墨烯基MOF材料在储能领域的实用化提供一定的技术支撑。该项目在执行期间，共发表的研究论文12篇，其中SCI收录9篇，作为第一作者、通讯作者或者共同通讯作者8篇；申请专利26篇。授权发明专利5项，培养硕士研究生4名。参加国际国内学术会议8次。