具有客体诱导突变性质的LIBs负极材料Guest@MOF的构筑及其储锂机制

How to improve the conductivity and specific capacity of metal-organic framework (MOF) is a key scientific problem for its application in efficient electrochemical energy storage systems. This project takes the fabrication of anode materials for lithium-ion batteries (LIBs) with high conductivity, stability and capacity as the research target. The guest with redox activity and π electron conjugated effect is introduced into the pores of activated host MOF with intrinsic lithium-storage abilities to construct Guest@MOF materials with hierarchical pores. The structural and physical characterizations, together with electrochemical properties and lithium-storage mechanism will be carried out to determine the relationships between various parameters (composition, microstructure, conductivity, porosity and stability) and lithium storage properties. The high-performance anode materials for LIBs will be obtained by adjusting and optimizing the structure and physical parameters of composites. The strong chemical bonding interaction and electronic coupling effect between the host framework and guest molecules in Guest@MOF can simultaneously improve the conductivity and stability of materials and produce guest-induced emergent properties. The interpenetrated and hierarchical pores provide fast channels for electron transportation and ion diffusion. The framework with rich nitrogen- and oxygen-functional groups affords numerous active sites for the adsorption of lithium ions, and facilitates the enhancement of specific capacities. The project might provide experimental evidence and theoretical guidance for the development of high-performance anode materials for LIBs.

如何提高金属有机骨架(MOF)的导电性和比容量是其应用于高效电化学储能系统亟需解决的关键科学问题。本项目以寻找兼具高导电性、高稳定性和高比容量的锂离子电池(LIBs)负极材料为目标，以具有本征储锂性能的活化MOF为主体，引入具有氧化还原活性和π电子共轭效应的客体，构筑具有多级孔结构的Guest@MOF新材料；结合结构测定、物性表征、电化学性能和储锂机制研究，探讨该类材料的组成、微结构、导电性、多孔性和稳定性等与其储锂性能之间的关系；通过调变和优化材料的结构和物性参数，获得高性能LIBs负极材料。Guest@MOF中主客体间强的相互作用可同时提高材料的导电性和稳定性，并可能产生客体诱导突变性质；相互贯通的多级孔结构为电子传输和离子扩散提供快速通道，富含N、O官能团的MOF为锂离子的吸附提供大量活性位点，有利于提高材料的比容量。本项目研究将为高性能LIBs负极材料的研发提供实验依据和理论指导。

锂离子电池（LIBs）具有高比能量、低成本和环境友好等特点，被认为是当前极具潜力的锂二次电池，如何提高金属有机框架（MOF）的导电性和比容量是MOF应用于高效电化学储能系统亟需解决的关键科学问题之一。本项目围绕MOF应用于LIBs负极时存在的关键问题开展研究工作，主要采用溶液浸渍、溶剂热和自组装等方法，通过对MOF主体进行硫化、与导电基底（碳布CC、石墨烯量子点GQDs、石墨烯泡沫GF和石墨烯气凝胶GA）复合以及引入具有氧化还原活性和π电子共轭效应的有机配体等手段可控构筑MOF及MOF基材料。通过本项目的研究，获得了11类集高导电性、高稳定性和高比容量于一体的LIBs负极材料，包括：CuS@Cu-BTC、ZnS@ZIF-8 (ZnS/NC)、Cu-TCNQ、Cu-BHT、Cu-BTC、CoFe-MOF (CoFeP)、Fe-MOF@CC (Fe2O3@CC)、ZIF-8@GQDs (NC@GQDs)、M-MOF@GF (MOx@GF) (M = Cu, Fe, Co, Ni)、CoM-MOF@GA (CoMOx@GA) (M = Fe, Co)和FeCo-MOF@GA (FeCoSe2@GA)。考察了上述电极材料的物相组成、结构特征、微观形态、导电性、多孔性和稳定性等，探讨了不同条件（硫化时间、MOF结构、导电基底种类和复合量以及各组元之间的协同作用）与电极材料电化学性能之间的内在联系，揭示了影响该类LIBs负极材料储锂性能的关键因素。本课题的实施与完成为新型高性能MOF及MOF基LIBs负极材料的开发和应用提供了实验依据和理论指导。