可拉伸聚合物电解质、硫化物复合电解质及电极界面修饰

Lithium metal batteries are attracting more and more attention due to the ultra-high theoretical capacity and the lowest theoretical potential of lithium metal anodes. However, the interface incompatibility between traditional liquid electrolyte and lithium metal anodes seriously hinders the development of lithium metal batteries which is manifested from different aspects such as the continuous side reactions, growth of lithium dendrites, significant volume change and unstable interphase, resulting in capacity decay and coulombic efficiency reduction as well as safety hazards..Although solid-state electrolytes show great advantages in terms of safety and electrochemical window compatibility, yet there are also a series of technical challenges. For example, the solid/solid interface can stabilize the cathode electrolyte interphase and inhibit the anode volume change. However, new interfacial problems occur such as low interfacial ion diffusion, large interfacial resistance, and heterogeneous interface stress. Hence, the interface optimization and the inherent property of the solid-state electrolyte are core problems for all solid-state lithium batteries..Aiming at the interface problems mentioned above of solid state lithium batteries, this project proposes a novel design of a kind of stretchable flexible polymer solid-state electrolyte and polymer-sulfide composite electrolyte, which can achieve multiple advantages including high ionic conductivity and high mechanical properties, so that it can well match with both high voltage cathode materials and high reactive lithium metal anodes at the same time, therefore improving the cycling stability, energy density and safety issues. Concretely, this new solid-state electrolyte utilizes two main properties i.e. the flexibility of the polymer electrolyte which can ameliorate the interface contact and the stretchable self-healing property which means the original structure can be restored when the structure is damaged by the interface stress. Overall, the ingenious design will make great contributions to reveal the fundamental mechanism of the interface between solid-state electrolyte and electrode materials as well as provide valuable theoretical basis and practical experience for excellent polymer solid-state electrolyte.

金属锂电池由于锂负极具有较高的理论容量、最低的理论电势而受到广泛关注。但在液态电解质中，锂负极与电解质界面持续发生副反应，生长锂枝晶，造成电池容量衰减和库伦效率降低，存在安全隐患。.固态电解质为锂电池的商用化提供了可能，但也面临新的技术挑战：一方面，固/固界面能够稳定正极界面，抑制锂负极的体积膨胀，另一方面也存在界面离子互扩散、界面阻抗、界面应力等问题。因此，对于全固态锂电池而言，核心关键一在于界面的调控与优化，二是固态电解质本身的性质。.针对固态电池中正负极材料与固态电解质的界面匹配性、固/固界面的稳定性、界面处的离子传导率、界面阻抗等关键科学问题，本项目提出设计并制备可拉伸离子导电弹性体聚合物电解质以及聚合物-硫化物复合电解质，使之兼具高离子电导率、高剪切模量，并通过先进的原位表征技术，结合理论计算和电化学测试，系统地研究界面阻抗、离子传输、界面应力与电解质结构之间的构效关系。

本项目以研发新型电解质为目标，从固态电池正负极材料与固态电解质的界面问题入手，创造性提出高盐浓度聚合物电解质和三维交联网络结构的聚合物界面材料。结合电化学测试手段和原位表征技术，对新型电解质的多级结构、界面性能与电化学性质进行系统研究，具有重要的学术前沿和产业实用价值。.1.设计一系列基于离子导电弹性体的新型聚合物固态电解质及聚合物—无机氧化物复合电解质，使之兼具高离子电导率、高剪切模量、宽电化学窗口，匹配高电压正极材料和金属锂负极。包括三方面：（1）采用光引发聚合法和功能性单体设计高盐浓度离子电导弹性聚合物电解质。（2）以液体电解液作为溶剂，功能性单体通过热引发或开环聚合进行原位聚合制备可拉伸的离子导电弹性体。（3）为了与上述目标聚合物电解质匹配、组装全固态金属锂电池，通过杂原子掺杂的超级多孔碳电化学预嵌锂制备多孔碳复合锂碳负极。.2.针对固态电池正负极的界面问题，系统研究新型离子导电弹性体聚合物-无机电解质复合电解质制备及性能研究、目标复合电解质与高电压型正极材料（钴酸锂正极材料）的界面匹配性能。.3.针对正负极界面失效机理进行系统研究。针对磷酸铁锂-石墨电池中所涉及到的正极界面失效原因进行分析，为其他高电压型正极材料的界面失效分析提供研究思路。针对高容量锂离子电池界面改性提出有效的改性策略，制备一类三维交联网状结构的聚合物界面材料，有效地改进界面失效问题。该三维交联网状结构的聚合物被证明具有更佳的机械性能，能更好地改善界面接触，提高界面稳定性，缓释界面应力-应变，抑制充放电过程中出现的体积膨胀。该项研究能够与电极材料紧密接触，有效降低界面阻抗，实现正负极界面良好的兼容性，对正负极界面的修饰具有不可替代的优越性。