复合固态电解质有机-无机界面离子传导机理研究

All-solid-state-lithium-batteries is one of the best strategies to solve the energy density and safety problem, which relies on the development of solid state electrolytes. Solid polymer electrolytes (SPEs) is one of the most promising electrolytes because of its light weight, flexibility, and machinability. However, the low ionic conductivity at room temperature inhibits its further application. Introducing the inorganic fillers and building the composite interface is an effective approach to increase it ionic conductivity. However, the ionic transport mechanism in the polymer-ceramic interface is still unknown. Through well-controlled fabricating the well-aligned and continuous polymer-ceramic interfaces in composite solid electrolytes, and the high resolution, in-situ, and real time characterization of the polymer segments configuration and Li+ spatial distribution using synchrotron radiation X-ray diffraction, solid lithium NMR spectrum, neutron reflection, and neutron depth analysis, this study will quantitatively analyze the impacts of interfacial geometries, the length and function groups of polymer segments, the density and anionic species of lithium salt, and the dielectric, interfacial space charge layer effect and Lewis acid-base characteristics of ceramic phase to the interfacial microstructures and local compositions, and further illustrate the ion transport paths and kinetics along polymer-ceramic interfaces, and their correlations with interfacial microstructures. This study aims to model the ion transporting process in in composite solid electrolytes, reveal the mechanism of fast ion transport along polymer-ceramic interfaces, develop the novel strategy to improve the ionic conductivity, and in turn carry out a fundamental and technical basis for the development and application of light-weight, highly-conductive, and processable polymer-ceramic composite solid electrolytes.

面向兼具超高能量密度和本征安全性的下一代可充电电池发展需求，全固态锂电池是最具潜力的技术路线之一，而固态电解质材料技术是实现全固态锂电池的重要基础。在各类固态电解质材料中，聚合物固态电解质因其较轻的质量密度、优异的柔韧性和良好的工艺兼容性等优势，最具实际应用的潜力。目前，聚合物固态电解质技术的主要挑战在于其室温离子电导率较低。通过引入无机填料形成有机-无机杂化界面，是提高聚合物基固态电解质离子电导率的最有效手段。然而，有关杂化界面离子传导及其增强机制的机理分析尚不明确，无法有效支撑高性能聚合物复合固态电解质的理性设计和技术进步。本项目通过在复合固态电解质中构建可控的、规则排布的、连续的有机-无机界面，结合高分辨、原位、实时的技术（例如TEM、同步辐射X射线衍射、固态锂核磁共振谱、原位实时中子反射和中子深度分析等），对聚合物链段结构与锂离子分布表征，定量分析有机-无机界面几何结构、聚合物链段长度、官能团种类、锂盐浓度与其阴离子种类、界面空间电荷层、无机相介电特性及其表面Lewis酸碱性等对界面微观结构和局部成分的影响机制，阐明有机-无机界面处的离子输运路径、动力学及其与微观结构的关联关系、探明有机-无机界面有效复合的材料结构、相结构以及微观结构的设计路线。本研究旨在构建复合固态电解质锂离子输运过程的物理模型，揭示有机-无机界面处离子快速输运的新机理，建立提升复合固态电解质离子电导率的新机制，为轻质、高导、且兼容现有电池工艺的聚合物基复合固态电解质实用化奠定理论与技术基础。

面向高比能高安全锂电池以固态电解质替代易燃的有机电解液成的发展需求，针对固态电解质室温离子电导率低的关键瓶颈问题，本项目发展了提高有机-无机复合固态电解质离子电导率的新途径。通过深入探索有机-无机复合固态电解质有机-无机界面处的聚合物链段分子结构与排布状态、锂离子分布情况，揭示了杂化界面离子传导机理。通过调控复合电解质无机相微观结构与聚合物分子结构，构建锂离子快速传输路径，开发出了室温离子电导率达到10-3 S cm-1固态电解质材料。共发表SCI论文11篇，申请发明专利4项，研究成果有望带动聚合物基复合固态电解质材料技术突破，支撑可实用化的下一代高比能量、高安全固态锂电池技术发展。