Collaborative Research: Effect of Cyclic Mechanical Stress on Ionic Conduction in Composite Polymer Electrolytes for Solid-State Batteries

该基金将研究循环机械应力如何影响用于固态电池的陶瓷-聚合物复合电解质中的离子电导率。固态电解质作为传统有机液体电解质的安全替代品正受到越来越多的关注，传统有机液体电解质易燃且容易过热。为了平衡高离子电导率和机械韧性，已经开发了几种复合聚合物电解质。然而，随着循环次数的增加，固态电池的性能往往会下降。当锂离子在不同的电极之间来回移动时，在充放电循环中会产生内应力。虽然电极的降解已被广泛研究，但对电解质内的机械和微观结构变化知之甚少。这种知识的缺乏限制了美国各行业安全、高性能储能系统的全面发展，包括电动汽车、便携式电子设备和生物医学设备。更全面地了解分散的刚性颗粒如何影响聚合物复合材料的机械行为，可能会进一步促进燃料电池、光伏、生物材料和柔性电子等其他应用的进步。这项资助支持的合作将吸引并联系一所主要本科院校和一所授予博士学位的研究型大学的教职员工和学生，这两所大学都是为西班牙裔服务的机构。陶瓷聚合物电解质的力学行为特别有趣，因为它涉及刚性颗粒和粘弹性基体之间材料性能的巨大差异，机械应力和电化学离子传输之间的高度耦合相互作用，以及陶瓷颗粒和聚合物链之间界面上的功能临界空间电荷区域。该项目的核心假设是，限制电池远程性能的一个因素（如容量衰减）是复合材料微观结构的粘弹性重塑。该项目有三个目标：(1)确定复合材料微观结构如何影响机械行为；(2)相互关联的动态应力和器件级电化学性能；(3)确定纳米级接触应力如何影响界面离子传导。利用互补的宏观尺度和纳米尺度实验，本研究将开发、询问和验证力学性能、微观结构和电化学性能之间相互依赖的多物理场模型。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。

This grant will investigate how cyclic mechanical stress affects ionic conductivity in ceramic-in-polymer composite electrolytes for solid-state batteries. Solid-state electrolytes are receiving increasing attention as safer alternatives to conventional organic liquid electrolytes, which are flammable and prone to overheating. Several composite polymer electrolytes have been developed to balance high ionic conductivity and mechanical toughness. However, solid-state batteries tend to suffer performance degradation with an increased number of cycles. Internal stresses develop during charging and discharging cycles, as lithium ions move back and forth between dissimilar electrodes. Although degradation of electrodes has been studied extensively, very little is known about mechanical and microstructural changes within the electrolyte. This lack of knowledge limits the full development of safe and high-performance energy storage systems for diverse U.S. industry sectors ranging from electric vehicles, portable electronics, and biomedical devices. A more complete understanding of how dispersed rigid particles affect the mechanical behavior of polymer composites may further contribute to advances in other applications such as fuel cells, photovoltaics, biomaterials, and flexible electronics. The collaboration supported by this grant will engage and connect faculty and students at a primarily undergraduate institution and at a PhD-granting research university, both of which are Hispanic-serving institutions.Mechanical behavior of ceramic-in-polymer electrolytes is especially intriguing because it involves a very large difference in material properties between rigid particles and a viscoelastic matrix, highly coupled interaction between mechanical stresses and electrochemical ion transport, and a functionally critical space-charge region at the interface between ceramic particles and polymer chains. The central hypothesis of the project is that a limiting factor for long-range battery performance (e.g., capacity fade) is viscoelastic remodeling of composite microstructure. The project is organized along three objectives: (1) determine how composite microstructure affects mechanical behavior, (2) interrelate dynamic stresses and device-level electrochemical performance, and (3) determine how nanoscale contact stresses affect interfacial ionic conduction. Using complementary macroscale and nanoscale experiments, this investigation will develop, interrogate, and validate a multiphysics model of the interdependencies among mechanical properties, microstructure, and 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.