基于自修复静电屏蔽效应构筑固态电解质及其抑制锂枝晶生长机制研究

固态电解质是高能高安全固态锂离子电池的关键材料，其实际应用却受制于界面接触性差、离子电导率低和锂枝晶生长的问题。本项目拟采用聚合物和锂镧钛氧(LLTO)构建三维网状结构固态电解质膜，通过物理掺杂、化学接枝引入金属阳离子或极性基团，实现基于静电屏蔽效应的固态电解质与锂金属界面的自修复与锂枝晶的控制生长。通过第一性原理计算结合表征技术研究金属阳离子、极性基团、聚合物的种类、含量和反应条件对固态电解质微观结构、缺陷和表面特性的影响规律，建立基于自修复静电屏蔽效应的聚合物/LLTO复合膜的可控制备方法；以研制的聚合物/LLTO复合膜组装固态锂离子电池，通过分子动力学模拟结合原位电化学测试和表征技术研究固态电解质膜微观结构与宏观力学性能、电化学性能的本质联系及锂离子传输机制，揭示自修复静电屏蔽效应抑制锂枝晶生长的机理。项目成果为新型固态电解质的设计合成及其在固态锂离子电池中的应用提供理论指导。

Solid-state electrolytes are the core components of solid-state lithium-ion (Li-ion) batteries with high energy capacity and safety, but their practical application is severely hampered by large interfacial resistance, low Li-ion conductivity and uncontrollable dendrite growth. In this proposal, we will fabricate three dimensional (3D) network structured polymer/LLTO composites with metal cation doping or polar groups grafting, which can force uniform lithium deposition and mitigate dendrite growth via self-healing electrostatic shield. First-principles combined with characterization technologies, are used to explore the influence of cation, polar group and polymer’s varieties, contents and reaction conditions on the microstructure, defect and surface property of the solid-state electrolyte. The controllable preparation methods of 3D network structured polymer/LLTO solid-state electrolyte based on self-healing electrostatic shield will be established. The essential relationship between microstructure and macroscopic mechanical properties and electrochemical performance as well as the mechanism of Li-ion transport will be investigated by the molecular dynamics simulation, in-situ scanning electrochemical technique and in-situ electrochemical impedance spectroscopy. The mechanism of dendrite-free solid-state electrolytes and Li-ion battery based on self-healing electrostatic shield is revealed. This research will provide theoretical basis and experimental guidance to the design and synthesis of novel solid-state electrolytes and their application in Li-ion batteries.