全固态锂电池固体电解质的关键问题

This project aims at developing high safety, high performance and long-term cycle stability solid state electrolytes and all-solid-state lithium rechargeable batteries that are used for power and energy storage batteries. The project will focus on the garnet-type solid state electrolyte, Li7La3Zr2O12 (abbreviated as LLZO). Novel, facile and highly efficient preparation methods toward nano-sized LLZO electrolytes will be developed for scalable production. Effects of ion doping on the ionic conductivities of LLZO will be studied to understand the impact of ionic crystalline occupation on the conductivities, and thereafter, the relationship between the structures and conductivities will be intensively understood. The mechanism of surface and interfacial defects that are responsible for the ionic transfer will be studied. Variable LLZO particles ranging from nanoscale to microscale with ionic conductivities greater than 10-3 S/cm at room temperature will be achieved via structural control and interfacial engineering. Polymer/LLZO composite electrolytes with excellent mechanical properties, high ionic conductivities and good interfacial flexibility will be further developed. On the basis of these studies, the compatibilities of solid state electrolytes with cathode and anode materials will be investigated to understand the key factors that affect the ionic transfer between electrolyte/electrode interfaces, on which a model of ionic transfer across the interface will be established. Finally, high performance and safe all-solid-state lithium rechargeable batteries will be assembled, which will provide theoretical and experimental basis for future applications.

本项目旨在解决动力和储能电池的安全性问题，发展高安全、高性能及长效稳定的固体电解质材料和全固态锂电池体系。着重研究石榴石型结构的锆酸镧锂Li7La3Zr2O12（LLZO）固体电解质。探索新颖、简易和高效的纳米LLZO固体电解质的宏量制备方法；研究离子掺杂对电导率的影响，揭示离子在不同晶格的占位对电导率的影响规律，深入理解结构与电导性能的关系；研究材料表面及界面化学缺陷对离子输运的作用机制，从而通过结构调控和界面工程获得室温离子电导率大于10-3 S/cm、颗粒尺度从纳米到微米量级可调的LLZO粉体材料。进而与聚合物电解质结合，开发出机械性能优、离子导电率高、界面柔韧性好的复合电解质。在此基础上，研究与固体电解质相匹配的正极和负极材料，揭示影响锂离子在电解质/电极界面传输的关键因素，建立界面离子的传输模型。最后构建高安全高性能的全固态锂电池，为将来的实用化提供理论基础和实验依据。

全固态锂电池是储能器件的学科前沿，也是新能源汽车、安全储能等产业的未来增长点。其中固体电解质性能的提升及固体电解质/电极界面是全固态锂电池的关键科学问题。开发了高离子电导率锆酸镧锂（LLZO）固体电解质粉体固相及燃烧合成技术，实现了LLZO颗粒尺度从纳米到微米的可控制备。深入研究了其结构与电导性能的关系，以及对空气的稳定性。设计了具有双三维导电网络结构的新型聚合物/陶瓷复合固体电解质，开发了超薄高陶瓷含量复合电解质膜卷对卷制备技术，突破了复合电解质膜制备的技术瓶颈。阐明了自外而内解决锂金属枝晶生长、体积变化的机制，开发了热熔融灌输法制备三维亲锂集流体复合锂负极的实用新方法。通过构筑聚合物软界面层、纳米无机过渡层解决了LLZO固体电解质与电极材料间的界面兼容问题；结合高温共烧和界面组分调控的方法制备复合正极，实现了高安全、高能量密度全固态锂电池制备并成功转化应用。研究成果不仅为高性能固体电解质和固态电池设计和制造提供了新思路，而且受到国内外同行广泛引用和充分肯定，以及效仿和跟踪。发表SCI论文113篇，IF>10论文51篇，ESI高被引10篇，热点论文2篇。受邀在Nat. Rev. Mater.，Joule等撰写综述。申请专利20项（授权8项），部分成果已经在企业转化和应用。主办2次全国学术会议并多次在国际会议上作邀请报告。项目组成员入选国家杰青、青年长江和泰山学者。获省部级一等奖1项。