UNS: Ion transport in semicrystalline solid polymer electrolytes

#1510092Li， christopher虽然目前最先进的锂离子电池（LIBs）已经广泛应用于消费电子产品中，但由于理论容量相对较低，无法满足电动汽车、自动驾驶飞机等应用的需求。用锂金属代替石墨作为阳极制备锂金属电池（LMB），可以大大提高锂金属电池的理论容量。实现LMB的最大障碍是相关的火灾或爆炸危险。为了实现LMB的安全运行，需要具有良好室温离子电导率和高剪切模量的固体聚合物电解质（spe）。本研究的目的是了解用于能量器件应用的半晶体spe中的离子传输机制。所提出的半晶体spe可能是制造下一代安全lmb的可行候选材料。在本文中，通过对过去四十年SPE研究的批判性分析，提出了一个被忽视的问题，即SPE中晶体形态对离子电导率影响的详细机制。为了回答这个具有挑战性的问题，PI提出了一系列精确控制晶体尺寸，取向和链折叠的半晶体spe。这种新颖的方法首次解耦了SPE中缠绕结构（扭曲度）和动态（拴链约束）对离子传输的影响。这也证明了与晶体形态相关的扭曲在半结晶spe中的离子传输中起着关键作用。提出的研究将为能源设备应用的spe设计提供一种新的策略：与现有的SPE相比，本文提出的晶体形态和取向可控的半晶SPE具有优势，因为晶体聚合物的力学强度比非晶橡胶聚合物高3-4个数量级，与半晶SPE相关的固有两相模型（晶体和非晶）分别满足了机械性能和高离子电导率两项性能指标的需求。提出的研究旨在解决能源研究领域的一个具有挑战性的问题。如果该项目成功，将开发出能够使锂金属电池安全运行的新型spe，这是能源研究界面临的重大挑战。这些拟议的教育活动具有广泛的影响。首先，将通过多种辅导项目，让高中学生和教师参与研究活动，缩小教育发展水平之间的差距。其次，由于费城地区未被充分代表的群体人口众多，拟议的外展计划将专门针对鼓励未被充分代表的群体参与。第三，通过科学媒体和公众研讨会宣传拟议的研究。这些信息的传播以及中学教育教师的实践经验将通过与费城周边地区的学区建立合作努力，使更多的教师有能力教育未来。

#1510092Li, ChristopherAlthough the current state-of-the-art lithium ion batteries (LIBs) have been widely used in consumer electronics, because of the relatively low theoretical capacity, they cannot meet the need of applications such as electrical vehicles, autonomous aircrafts, etc. The theoretical capacity of LIBs can be greatly improved by replacing graphite with lithium metal as the anode to fabricate a lithium metal battery (LMB). To materialize LMB, the biggest obstacle is the associated fire or explosion hazards. In order to achieve safe operation for LMB, solid polymer electrolytes (SPEs) with good room temperature ionic conductivity and high shear modulus are needed. The goal of this proposed research is to understand the ion transport mechanism in semicrystalline SPEs for energy device applications. The proposed semicrystalline SPEs could be a viable candidate for fabricating next generation safe LMBs. In this proposal, through critical analysis of the past four decades of research on SPE, an overlooked question regarding the detailed mechanism of the crystalline morphology effect on ionic conductivity in SPEs has been raised. To answer this challenging question, the PI proposes a series of semicrystalline SPEs with precisely controlled crystal size, orientation, and chain folding. This novel approach, for the first time, decouples the intertwine structural (tortuosity) and dynamic (tethered chain confinement) effects on ion transport in SPE. It also demonstrates that tortuosity associated with crystalline morphology plays a critical role on ion transport in semicrystalline SPEs. The proposed research will provide a new strategy to design SPEs for energy device applications: Compared with existing SPEs, the proposed semicrystalline SPE with controlled crystal morphology and orientation is advantageous because crystalline polymer is mechanically 3-4 orders of magnitude stronger than amorphous rubbery polymers, the intrinsic two-phase model (crystalline and amorphous) associated with semicrystalline SPE addresses the needs for two performance measures, the mechanical properties and the high ionic conductivity, respectively. The proposed research aims to tackle a challenging problem in the energy research field. If successful, the project will lead to a new type of SPEs, which enables safe operation of lithium metal batteries, a grand challenge facing the energy research community. These proposed educational activities encompass a broad impact. First, the proposed plan will help bridge the existing gap between levels of educational developments by involving high school students and teachers in research activities through a number of mentoring programs. Second, due to the high population of under-represented groups in the Philadelphia region, the proposed outreach program will be specifically geared towards encouraging the participation of under-represented populations. Third, the proposed research will be publicized through scientific media and public workshops. The dissemination of this information along with hands-on experiences for secondary education teachers will result in more informed teachers capable of educating the future by establishing collaborative efforts with school districts in the surrounding Philadelphia region.