Multifunctional Zwitterionic Solid Polymer Electrolytes for High-Performance Lithium-Ion Batteries

锂离子电池（LIBs）由于其高能量密度、高工作电压和良好的循环性能，在便携式电子设备和电动汽车的最流行的能量存储系统中发挥了关键作用。然而，使用有机液体电解质的商用lib存在不可控制的副反应和严重的安全问题，如有毒液体电解质泄漏、电解质易燃性和热稳定性差。因此，用固体电解质代替液体电解质是非常必要的。在几种固体离子导体中，固体聚合物电解质（spe）具有优异的柔韧性、与电极的界面相容性、良好的可加工性、低成本和重量轻等优点，克服了陶瓷离子导体的局限性。然而，目前的spe往往存在机械强度和尺寸热稳定性差、电化学稳定性差、室温下锂离子电导率低等局限性。该研究将研究分子水平的设计原理，以建立离子导电聚合物的分子结构与spe的机械/电化学性能之间的关系。该项目将促进我们对下一代全固态锂离子电池多功能聚合物电解质设计原则的理解，并在开发可持续能源生产和减缓全球变暖的储能技术方面发挥关键作用。该项目将支持和培训两名研究生和几名本科生，并为高中学生和教师提供免费的实践研究经验，这将有助于将研究方法传播到更广泛的社区。该项目将使一系列具有优异电化学和机械稳定性的锂离子导电两性聚氨酯（zPU）电解质的分子水平设计成为可能。研究不同系留阴离子基团、系留正离子与阴离子基团之间的间隔剂长度以及聚合物骨架结构对聚合物电解质材料性能的影响。理论原子分子模型将用于研究锂盐的溶解和溶解以及锂离子在两性离子聚氨酯中的传输机制。将采用一套电化学表征方法结合理论分子模拟研究，系统地研究离子电导率、界面稳定性和电池充放电过程中的性能。提议的努力是围绕着聚合物化学家、分子模拟科学家和膜电化学家之间的合作，以推进对zPU spe相关性的理解。研究结果将用于设计具有最大电化学性能的下一代固态电池。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Lithium-ion batteries (LIBs) have played a key role in the most popular energy storage systems for portable electronic devices and electric vehicles, owing to their high energy density, high operating voltage, and good cycling performance. However, commercial LIBs with the organic liquid electrolyte are associated with uncontrollable side reactions and critical safety issues such as toxic liquid electrolyte leakage, flammability of electrolytes, and poor thermal stability. Therefore, replacing the liquid electrolyte with solid electrolytes is quite necessary. Among several solid ion conductors, solid polymer electrolytes (SPEs) can offer excellent flexibility, interfacial compatibility with electrodes, good processibility, low cost, and light weights that can overcome the limitations of ceramic ion conductors. However, current SPEs often encounter limitations such as poor mechanical strength and dimensional thermal stability, inferior electrochemical stability, and low lithium-ion conductivity at room temperature. The proposed research will study molecular-level design principles to establish relationships between the molecular structures of ion-conducting polymers and the mechanical/electrochemical performances of SPEs. This project will advance our understanding of the design principles of next-generation multifunctional polymer electrolytes for all-solid-state lithium-ion batteries and play a critical role in developing energy storage technologies for sustainable energy generation and global warming mitigation efforts. The project will support and train two graduate students and several undergraduate students, and complimentary hands-on research experiences for high school students and teachers will help to disseminate the research methods to a broader community.This project will enable the molecular-level design of a series of lithium ion-conducting zwitterionic polyurethane (zPU) electrolytes with excellent electrochemical and mechanical stabilities. The effect of different tethered anionic group, length of spacers between tethered cationic groups and anionic groups, and polymer backbone structure will be investigated to develop high-performance polymer electrolyte materials. Theoretical atomistic molecular modelling will be employed to investigate the dissolution and dissolution of lithium salts and lithium-ion transport mechanisms in zwitterionic polyurethanes. A suite of electrochemical characterization methods combined with theoretical molecular simulation studies will be employed to systematically investigate ion conductivity, interfacial stability, and battery performance during charging/discharging. The proposed effort is centered around a collaboration between a polymer chemist, a molecular simulation scientist, and a membrane electrochemist to advance understanding of the correlations of zPU SPEs. Results will be used to design next-generation solid-state batteries with maximum electrochemical performance.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.