单离子导体聚合物锂金属二次电池界面演化的电化学原位磁共振成像研究

Polymer single ion conductor is a promising electrolyte to institute the PEO-based electrolyte for rechargeable lithium metal batteries. Therefore, it is necessary for us to study the relationship between the structure and performance of the materials, as well as its impact on the Li/polymer interface layer (Li dendrite, Li and polymer surface) for lithium metal batteries systematically. In situ magnetic resonance provides the NMR signal in the time and space resolution of the object, which is a powerful method for understanding the information involving the evolution of Li dendrite, Li surface film, structure of electrolyte and cathode materials during the operation of lithium metal batteries. In the project, we will firstly build the in situ electrochemical MRI (in situ MRI) probe, which will be applied to study the polymer single ion conductor-based lithium metal batteries in combination with the solid-state NMR, SAXS, and TEM characterizations. The structure information such as the ionic transport path, pore structure and framework of the polymer as well as the properties such as mechanical property, ionic conductivity, lithium ion transference number, and the interface stability will be characterized for understanding the relationship of structure and properties of the polymer. Afterwards, stability of lithium morphology, Li surface film and polymer surface in the lithium metal batteries using the polymer single ion conductor with different structure will be further investigated for analyzing the influence of the microstructure of the material on the performance of lithium metal batteries. The research results of this project will provide an important theoretical and technical guide to the future development and research of polymer single ion conductor-based lithium metal batteries. The in situ MRI method will be further developed in the project, too.

鉴于聚合物单离子导体是替代PEO类电解质的重要电解质类型，深入研究该类材料的结构和性能关系以及对Li/聚合物界面(枝晶、锂表面膜和聚合物表面)的影响很有必要。原位磁共振成像可获取研究对象的时空分辨NMR信号，提供锂金属电池运行时锂枝晶、锂表面膜、正极和电解质结构和组分的演化信息。本项目拟首先构建电化学原位磁共振成像方法，并结合固体NMR、SAXS、TEM等详细表征单离子导体聚合物的离子传输通道和孔道结构等结构性质，分析材料的机械性能、离子导电率和锂离子迁移数和电化学稳定窗口等性能，深入理解材料结构和性能的关系，并以此为基础研究不同结构的单锂离子导体聚合物对锂/聚合物界面包括锂表面形貌和表面膜及聚合物表面稳定性的影响，指导该材料设计和制备，为构筑高性能聚合物单离子导体锂金属二次电池提供重要的实验数据和理论支持，并在此过程中进一步发展应用电化学原位磁共振成像技术。

本项目重点开展了电化学原位磁共振成像方法的构建，着重研究了钠/锂金属电极在循环过程中的枝晶、死钠/锂和固体电解质界面层的演化过程；项目在开展期间，还主动将固体核磁共振谱学技术应用在一些重要电池材料体系如氟化碳、红磷和P2型锰酸钠材料的研究中，扩大了课题的研究内容内涵和外延。本项目在国际学术刊物上正式发表SCI论文4篇，其中JCR一区期刊Nano Energy，Angewandte Chemie，Journal of Materials Chemistry A 各1篇，Frontier in Chemistry 1篇，取得了重要的研究成果。同时以课题为依托培养硕士研究生1名。

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