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固态电池陶瓷聚合物复合电解质的离子电导率。固态电解质作为传统有机液体电解质的更安全的替代品正受到越来越多的关注，传统有机液体电解质是易燃的并且易于过热。已经开发了几种复合聚合物电解质来平衡高离子电导率和机械韧性。然而，固态电池倾向于随着循环次数的增加而遭受性能退化。在充电和放电循环期间，随着锂离子在不同的电极之间来回移动，内应力会产生。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安全和高性能储能系统的全面发展，这些系统适用于从电动汽车、便携式电子产品和生物医学设备等不同的美国工业部门。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，可能会进一步促进其他应用领域的发展，如燃料电池、光电子学、生物材料和柔性电子器件。这项资助支持的合作将吸引并连接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师和学生，这两所大学都是西班牙裔服务机构。陶瓷聚合物电解质的机械行为特别有趣，因为它涉及刚性颗粒和粘弹性基质之间材料性质的巨大差异，机械应力和电化学离子传输之间的高度耦合的相互作用，以及陶瓷颗粒和聚合物链之间的界面处的功能临界空间电荷区域。 该项目的中心假设是，远程电池性能的限制因素（例如，容量衰减）是复合材料微结构的粘弹性重塑。该项目是组织沿着三个目标：（1）确定复合材料的微观结构如何影响机械行为，（2）相互关联的动态应力和设备级的电化学性能，（3）确定纳米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，这项研究将开发，询问和验证机械性能，微观结构和电化学性能之间的相互依赖性的多物理模型。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.