CMF基双金属氧化物-石墨烯复合负极材料的可控构筑及电化学协同储锂机制研究

Metal oxides are a kind of very promising lithium-ion battery (LIBs) anode materials. However, metal oxides suffer from low conductivity and large volume change during charge-discharge cycles. This project will design and prepare hollow/porous bimetal oxides-graphene nanocomposites to fully improve the lithium storage performance of metal oxide anodes, in which the hollow/porous nanostructure can alleviate the volume change of the electrodes during charge-discharge cycles, graphene can enhance the conductivity and structural stability of the electrodes, and the synergistic effect between different metals can improve the electrochemical performance of the materials. The cyanometallic framework (CMF) compounds are selected as the precursors for hollow/porous bimetal oxides. To achieve the hollow/porous bimetal oxides-graphene nanocomposites, the CMF compounds will first be combined with graphene oxide to form composite precursors through in-situ synthesis or self-assembly methods. With the following heat treatment process, hollow/porous bimetallic oxide-graphene nanocomposites are prepared. The modulation method of metal oxide hollow/porous nanostructures in the composites will be systematically studied, the key factors affecting the combination modes of metal oxides and graphene will be investigated, and the controllable synthesis rule will be revealed. On this basis, the lithium storage properties of the composite materials will be systematically studied by electrochemical methods. The relationship between the composition and structure of the composite system and the lithium storage properties will be investigated in detail. With the assistance of electrochemical in-situ spectroscopy techniques, the electrochemical synergistic lithium-storage mechanism of the composite materials will be clarified. It is expected that the study in the project can lay experimental and theoretical basis for the development and application of high-performance metal oxide-based LIBs anode materials.

金属氧化物是一类极具发展潜力的锂离子电池负极材料，但其存在电导率低以及充放电过程中体积变化大等问题。本项目以全面提升氧化物基负极性能为基本目标，以中空/多孔双金属氧化物-石墨烯复合材料为研究对象，拟利用中空/多孔结构克服充放电循环中电极材料的体积变化，利用石墨烯提高电极的导电性和结构稳定性，利用双金属协同改善材料的电化学性能。选择氰合金属框架（CMF）化合物为前驱体，通过原位合成或自组装方法与氧化石墨烯形成复合前驱体，再通过热处理等手段构建新型的中空/多孔双金属氧化物-石墨烯复合材料。系统研究复合体系中氧化物中空/多孔纳米结构的调制方法，探寻影响氧化物与石墨烯复合方式的关键因素，揭示可控合成规律。在此基础上，系统研究材料的储锂性能，考察复合体系的组成、结构与储锂性能的关系，结合电化学原位谱学技术揭示复合体系的电化学协同储锂机制，为高性能氧化物基负极的研发和应用提供理论和实验依据。

本项目针对金属氧化物负极体积膨胀大、导电性能差的不足，从微纳结构设计和组份调控两方面共同提升氧化物负极的储锂性能。项目选择基于 [Ni(CN)4]2-、[Fe(CN)5NO]2-、[M(CN)6]3/4- （M = Fe, Co）和 [M(CN)8]4- （M = Mo, W）等构筑基元的氰合金属框架化合物 (CMF) 为前驱体，用简单的热处理方法构建了多种具有中空/多孔结构的双金属氧化物，并通过原位合成方法构筑了系列双金属氧化物（合金）与石墨烯（rGO）的复合材料，包括ZnO-NiO蛋黄-壳结构微球，具有核壳、中空和分级结构的Fe0.8Mn1.2O3多面体，Fe2O3-MoO3多孔八面体，含有氧空位的Fe2WO6分级多孔八面体，CoWO4/Co3O4分级结构核壳八面体，具有石墨烯包裹结构的Co3O4-CoFe2O4@rGO，含氧空位的SnO2-x-Fe2O3/rGO，以及NiFe-NiFe2O4/rGO、Mn3O4-Fe3O4/rGO、Ni-NiO-MoO2/rGO、Zn2Mo3O8/ZnO/rGO、FeWO4/Fe2O3/rGO、ZnWO4/ZnO@C/rGO等复合材料，实现了对材料组成和微纳结构的可控合成。系统研究了材料作为锂离子电池负极的储能性能，阐明了材料组成和微纳结构与储锂性能的关系，揭示了电极在循环过程中的电化学重构现象及复合体系的电化学协同储锂机制。发现双金属协同能够有效改善材料的电化学性能、中空/多孔结构能够有效缓解充放电循环中电极材料的体积变化、引入石墨烯能够有效提升电极的导电性和结构稳定性。并通过 [W(CN)8]4- 引入重元素钨解决了中空/多孔材料体积比容量低的问题，实现了超高的体积容量。研究成果已在SCI源期刊发表学术论54文篇，申请国家发明专利8件，获授权5件，培养研究生11人。研究成果对于高性能氧化物基负极材料的开发和应用具有重要的指导作用。