基于锂基合金负极的大容量固态锂二次电池研究

Secondary batteries based on lithium metal anodes and solid electrolytes are considered as a very promising system of next generation energy storage due to their low cost, high safety and environment friendliness. This new system needs to be intensively studied from the aspects of the electrochemical reaction mechanism of the interface, the transport characteristics of bulk materials and the design optimization of materials. In this project, oxygen and sulfur are selected as the active materials of the solid-state batteries with lithium-based anodes. Besides, three typical interfaces of lithium/solid electrolyte, oxygen/solid cathode and sulfur/solid electrolyte are studied as research subjects. On this basis, further and intensive research will be conducted on the mechanism of charge transfer at the oxygen/catalyst interface and lithium ion transport of the solid-state lithium air batteries and the formation and decomposition mechanism of lithium sulfur on the surface of the electrolyte of the solid-state lithium sulfur batteries. Moreover, the project focuses on the ion migration problem and improvement of the solid-solid interface and the gel and polymer are introduced to reduce the interfacial resistance. Through the investigation of solid electrolyte, alloy anode, cathode catalytic materials and battery system design and optimization, this project will greatly raise the power, life and energy storage efficiency, laying a solid research foundation for the practical application of solid state lithium secondary battery.

基于金属锂负极和固体电解质的二次电池由于低成本、高安全和环境友好等优势被认为是极具希望的下一代储能体系。这种新型体系从界面电化学反应机理、体相物质输运特征、材料的设计优化等方面都需要做深入的研究。本项目选择氧和硫单质作为锂基负极固态电池的正极活性物质，以锂/电解质、氧气/固态正极和硫/固态电解质这三种典型的界面为研究对象。深入研究固态锂空气电池中氧气/催化剂界面电荷传递和体相锂离子迁移机制，以及固态锂硫电池电解质表面硫化锂生成和分解机理。重点关注固固界面离子迁移问题和改善方案，引入凝胶和聚合物以降低界面阻抗。本项目通过对固体电解质、合金负极、正极催化材料、及电池体系的优化设计和匹配，大幅提高固态锂二次电池的功率、寿命和储能效率，为固态锂二次电池的实用化打下坚实的理论研究基础。

本项目围绕基于锂基合金负极的大容量固态锂二次电池，从正极催化材料、固体电解质、合金负极、电极/电解质界面及电池体系的优化设计和匹配等方面开展了大量研究工作。（1）在锂空气电池正极催化剂研究方面：设计制备出多种三维多孔空气电极；提出了液固催化空气电极新机制；通过建立在线差分电化学质谱和原位拉曼增强光谱分析技术，阐明了正极/电解质多相界面的物质迁移机理；提出了锂空气电池副产物碳酸锂的分解机制；实现了基于氧化锂/过氧化锂转换的封闭锂空气电池。（2）在锂空气电池电解质研究方面：通过引入电解质添加剂优化电池反应动力学，并探究了电解质和负极材料的匹配机制；研究了高效熔融盐电解质在锂-二氧化碳电池中电化学行为；开发了组合电解质、去溶剂化电解质等拓宽电池的电化学窗口。（3）在合金负极研究方面：利用多孔负极结构，分别引入外界O2、电解液添加剂CO2保护锂负极；设计了高浓度多元盐电解液体系，提高金属锂负极的库伦效率；利用预处理法构筑稳定无枝晶的锂金属负极；以及开发出新型锂硅合金负极、铜硅纳米线复合负极。（4）在锂硫电池穿梭效应抑制研究方面：开发了高效催化剂提高多硫离子转化动力学；制备出多种多功能隔膜锚定多硫离子，改善电池稳定性；探究了硫化聚(丙烯腈)正极的固-固转化行为。（5）在全固态电池研究方面：开发了多种基于固态电解质LAGP的全固态电池；通过引入无机保护层、聚合物中间层等方式优化固态电解质/负极界面；设计制备了受太阳能驱动下可在超低温下稳定运行的全固态锂空气电池；提出了空气电极界面空间电荷层对于电池体系离子输运的影响；通过引入聚合物凝胶改进固态锂硫电池正极/电解质界面；以及开发出新型的全固态锂碘电池。通过以上研究，固态锂二次电池的功率、寿命和储能效率等性能得到大幅提高，为固态锂二次电池的实用化打下了坚实的理论研究基础。