CAREER: Engineering Structure and Ionic Conductivity in Li7La3Zr2O12 Nanowire-Based Solid Electrolytes

职业：Li7La3Zr2O12 纳米线固体电解质的工程结构和离子电导率

基本信息

批准号：
1553519
负责人：
Candace Chan
金额：
$ 55万
依托单位：
Arizona State University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-06-01 至 2022-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1553519&HistoricalAwards=false
关键词：
CAREER Engineering Structure Ionic Conductivity

项目摘要

NON-TECHNICAL DESCRIPTION: Lithium ion batteries are ubiquitous in laptops and cell phones and may gain more use in transportation applications in the near future. However, these batteries suffer from safety issues originating from the flammable liquid electrolyte that is used to transport lithium ions within the battery. One of the most promising candidates for a safer, replacement electrolyte is the ceramic lithium lanthanum zirconate (LLZO), which has good thermal/chemical stability and ionic transport properties. Nonetheless, there is still much fundamental research needed in order to improve understanding of several critical issues in LLZO and how to improve its performance. This project investigates novel LLZO nanowire structures and composites with unique nanoscale properties that can improve their conductivity for lithium ions and integration into safer, all-solid-state batteries. This project also supports education and outreach activities that focus on improving the pipeline and retention of female students in science and engineering through hands-on experiences that will increase understanding and retention of engineering concepts and stimulate the students' interests in research. Outreach to local middle school girls through a battery-related challenge to provide context on issues related to electric cars and research opportunities to high school, undergraduate, and graduate students are example activities. Educational efforts include international exchange of teaching methodologies with faculty in South Korea to understand strategies that promote female student achievement, as well as how to best engage students from diverse backgrounds in student-centered learning environments.TECHNICAL DETAILS: This research project aims to correlate composition, grain boundary structure, and crystal phase with ionic conductivity in LLZO nanowire materials prepared using electrospinning. Nanowire solid electrolytes can offer characteristics that are beneficial and advantageous compared to bulk materials - namely milder calcination conditions for crystallization, stabilization of metastable phases, and opportunities for unique structures such as core-shell composites. These characteristics can lead to properties that improve the ionic conductivity, sintering ability, and integration of the electrolytes into all-solid-state batteries. The nanowires are used to understand the LLZO phase stability, crystallization, and sintering processes. Core-shell nanowire structures are used to investigate interfacial properties and transport in composites to understand how to maximize highly conducting pathways for lithium ions and uniformly modify grain boundaries. Additionally, detailed in situ and aberration-corrected transmission electron microscopy is used to understand processes such as crystallization of electrospun nanowires, impurity segregation to grain boundaries, sintering in networks of nanowires, and interdiffusion at the electrolyte/cathode interface. This information is being correlated with ionic conductivity and electrochemical cycling tests on the nanowire solid electrolyte materials and compared to bulk materials. The insights gained from this work are enabling better control of composition, stabilization of metastable phases, sintering processes, and Li ion transport, which can ultimately lead to higher ionic conductivity ceramic electrolytes.

非技术描述：锂离子电池在笔记本电脑和手机中无处不在，并且在不久的将来可能会在交通应用中得到更多使用。然而，这些电池存在因用于在电池内传输锂离子的易燃液体电解质而产生的安全问题。最有希望的更安全的替代电解质之一是陶瓷锆酸锂镧 (LLZO)，它具有良好的热/化学稳定性和离子传输特性。尽管如此，为了提高对 LLZO 几个关键问题以及如何提高其性能的理解，仍然需要进行大量基础研究。该项目研究具有独特纳米级特性的新型 LLZO 纳米线结构和复合材料，可以提高其锂离子传导性并集成到更安全的全固态电池中。该项目还支持教育和外展活动，重点是通过实践经验改善女学生在科学和工程领域的培养和保留，这将增加对工程概念的理解和保留，并激发学生的研究兴趣。通过与电池相关的挑战向当地中学生进行外展活动，为高中生、本科生和研究生提供有关电动汽车问题的背景信息和研究机会。教育工作包括与韩国教师进行教学方法的国际交流，以了解促进女学生成绩的策略，以及如何在以学生为中心的学习环境中最好地吸引来自不同背景的学生。技术细节：该研究项目旨在将作文关联起来使用静电纺丝制备的 LLZO 纳米线材料中的晶界结构和具有离子导电性的晶相。与块体材料相比，纳米线固体电解质可以提供有益且有利的特性，即更温和的结晶煅烧条件、亚稳态相的稳定以及形成核壳复合材料等独特结构的机会。这些特性可以提高离子电导率、烧结能力以及将电解质集成到全固态电池中。纳米线用于了解 LLZO 相稳定性、结晶和烧结过程。核壳纳米线结构用于研究复合材料中的界面特性和传输，以了解如何最大化锂离子的高导电路径并均匀地修改晶界。此外，详细的原位和像差校正透射电子显微镜可用于了解电纺纳米线的结晶、晶界的杂质偏析、纳米线网络中的烧结以及电解质/阴极界面处的相互扩散等过程。该信息与纳米线固体电解质材料的离子电导率和电化学循环测试相关，并与散装材料进行比较。从这项工作中获得的见解能够更好地控制成分、亚稳态相的稳定、烧结过程和锂离子传输，最终可以产生更高离子电导率的陶瓷电解质。