以钴基MOFs为前驱体定向合成碳包覆氧化钴/氮掺杂石墨烯复合材料及其储锂性能研究

The development of new composite method and controllable preparation method is the forefront of the challenge to further improve the energy density and rate performance of anode for lithium-ion batteries. Based on our previous work, the project will directly design the controllable growth cobalt based metal-organic frameworks (Co-MOFs) as precursor. The nitrogen source will be added in the combination of Co-MOFs and graphene oxide, while the pyrolysis way will be effectively controlled to realize the directional synthesis of carbon-coated cobalt oxide/nitrogen- doped graphene composites. The chemical composition, microstructure and multistage morphology of each step product will be carried on detailed tracking and characterization. The lithium storage properties of series of composites will be comprehensively evaluated and compared by these key indicators such as the specific capacity, coulomb efficiency, cycle performance and rate capability. Firstly, we will directionally select Co-MOFs with chemical characteristics (different category of ligands, network and porous structure), explore the in-situ growth regularity of the selected Co-MOFs on graphene oxide sheets, and then clarify the correlation of the pyrolysis conditions of Co-MOFs and the microstructure of target product (multiple composites). The controllable effect of the chemical composition and microstructure of composite material on the corresponding energy density and rate capability will be further elucidated. The research results will provide the demonstration for controllable preparation novel anode for high-performance lithium-ion batteries.

发展新的复合方式及可控制备方法是进一步提升锂离子电池负极材料能量密度和倍率性能的前沿挑战。本项目在前期工作基础上拟以定向设计可控生长的钴基金属-有机框架(Co-MOFs)为前驱体，通过与氧化石墨烯结合，导入氮源和有效控制热解方式，定向合成碳包覆氧化钴/氮掺杂石墨烯复合材料。通过对产物的化学成分和多级形貌进行详实跟踪和表征，从比容量、库伦效率、循环性能和倍率性能等关键指标综合评估和对比系列复合物的储锂性能。探究定向选择的不同类别配体、网络和多孔结构等化学特征的Co-MOFs与氧化石墨烯原位生长上的规律性，探讨Co-MOFs热解条件与目标产物多元复合材料微结构的相关性。进一步探索复合材料化学组成和微结构对能量密度和倍率性能的调控效应，进而为新型高性能锂离子电池复合负极材料的可控制备提供实例。

基于钴基金属-有机框架(Co-MOFs)的新型复合材料的设计和可控制备是提升锂离子电池负极材料电化学性能的关键，已成为当今化学、材料、工程和环境等交叉学科的研究热点之一。本项目以含氮或含氧类别的配体定向设计了可控生长的系列MOFs材料为前驱体，通过与氧化石墨烯或其他碳类材料结合，使用有效的可控热解方式，定向合成钴基化合物与石墨烯复合材料，主要涉及其导电性和稳定性的改进、电反应活性位点的增加和复合材料的结构与电化学性能之间的构效关系等相关研究。通过这些工作的开展，开发了基于MOFs后合成修饰的系列电化学材料，提出了复合材料之间相互作用与性能的关系新机理，探索钴基簇合物的热解反应机理，建立了利用石墨烯复合、金属掺杂、原位生长、表面改性等策略定向合成特定电化学材料的新方法。并极大创新了MOFs基材料的复合方式和丰富了锂离子电池中电极材料和电催化材料的种类。这些工作的开展为获得具有应用价值的MOFs基复合材料提供了重要的技术支持和理论参考。目前该研究已取得了系列研究成果，在包括Nano Energy, Chem. Eng. J., Angew. Chem. Int. Ed., Science Bulletin和Electrochim. Acta等国际著名期刊发表SCI论文11篇，且1篇论文入选ESI高引论文，申请发明专利4项，并在项目资助下，现已培养或协助培养硕士研究生7名。