基于原位制备单离子导体功能涂层的金属锂负极保护

Due to it's high specific capacity and low reduction potential, lithium metal is considered to be an ideal anode material for high energy lithium batteries. However, uncontrollable lithium dendrite formation on the lithium anode during the charge and discharge processes is an urgent problem to be solved. Single ion conducting polymer electrolytes (SIPEs) significantly retarded the formation of lithium dendrite. However, their low room-temperature ionic conductivity values have limited practical application. In this project, commercial liquid electrolyte will be used as lithium ion conductor, the thin SIPEs functional layer will be placed on the surface of the Li metal to prevent the formation of lithium dendrite from it's roots. Size-controllable functionalized SIPEs willed be designed, ionic conductivity, lithium ion transference number and mechanical property of the SIPEs will be characterized and systematical structure-performance relationships will be summarized by combining the experimental test with first principle study. The microporous ion transport channels will be controllably constructed during fabrication of three dimensional SIPEs films via in-situ polymerization. Then the prepared thin film will be laminated with lithium foil by decal transfer technique, the effect of microstructure on interfacial properties will be characterized and the microscopic mechanism of lithium dendrite inhibition shall be revealed by combining the experimental synthesis with computational molar dynamic modeling, electrochemical characterization, stability measurements and battery performance evaluation. This project will allow rapid Li+ transport and stable Li electrodeposition, safety of lithium metal will therefore be significantly improved. The proposal is of great reference value to the development of other metal anode batteries.

锂金属具有高理论比容量及低电势等特点，是理想高能锂电池负极材料，然而充放电过程中锂枝晶生长是亟需解决之难题。单离子传导聚合物电解质可显著延迟锂枝晶形成，但低的室温离子电导率限制其实际应用。本项目采用商业电解液传导锂离子，以单离子导体为锂负极功能涂层，从根源抑制锂枝晶生长。设计尺寸可控功能型单离子聚合物，通过第一性原理计算，结合实验测试，研究聚合物的离子传输效率、锂离子迁移数和机械性能，总结微观结构与电解质性能之间的构效关系；通过原位聚合手段制备高稳定性三维电解质薄膜，采用印花转移技术将薄膜与锂片复合；结合分子动力学模拟、电化学表征、稳定性测试和电池性能评估，研究离子传输通道和薄膜厚度对离子电导率、锂离子迁移数、离子传输速率、机械性能等界面性能的影响规律，揭示锂枝晶抑制的微观机制。本项目同步实现高效锂离子传导和稳定锂电沉积，提升锂金属电池安全性，对其他金属负极电池发展亦有参考价值。

本项目围绕研究目标，按照具体研究方案，设计合成了具有单离子传导特性的聚合物材料，系统研究了其作为不同功能结构的电化学行为，揭示了单离子传导特性与抑制金属枝晶生长和阻挡多硫阴离子穿梭的作用机制。根据关键科学问题，取得了一系列列的研究进展，完成了既定的目标。主要成果可简单概括为四点：(1)单离子传导聚合物用作电解质隔膜，能够有效抑制锂枝晶的生长，同时提高锂金属电池循环性能；(2)系统研究了具有刚柔并济结构的单离子传导聚合物材料用作锂金属负极人工SEI涂层，对锂金属电池综合性能影响；(3)研究单离子传导聚合物材料用作锂硫电池隔膜修饰层，抑制多硫阴离子穿梭效应的作用；(4)将研究思路拓展到其他体系电池中，研究单离子导体对金属枝晶抑制的普适性，为设计高安全，高比能储能装置，提供研究基础。三年来，在项目资助下共发表9篇学术论文，包括Journal of Membrane Science(1)、Journal of Alloys and compounds(1)、Energy Technology(1)、Fuel(1)、其他文章5篇。积极参加国内学术会议。在本项目资助下，指导硕士研究生4人次，其中1人获得硕士学位。