CAREER: Regulating the Interface Chemistry of Sodium Ceramic Electrolytes for Solid-State Sodium Metal Batteries

非技术型锂离子电池，钠离子电池因其类似的电池化学成分、高丰度的钠源、低钠原料成本和可获得性，在交通电气化和大规模储能方面显示出巨大的潜力。与此同时，固态电池使用不可燃的固体电解液取代易燃的液体电解液，为缓解阻碍电池技术进步的火灾危险提供了革命性的解决方案。高性能固态钠电池发展的主要挑战之一是钠陶瓷固体电解液与电极材料之间存在较大的界面电阻。这个职业奖项项目由材料研究部陶瓷项目和既定的激励竞争研究计划(EPSCoR)联合支持，通过调节电解液表面性质，解决了钠金属电极和钠陶瓷固体电解质之间面临的关键界面挑战。Pi和她的研究小组寻求对钠陶瓷固体电解质的界面结构-组成-性能关系的基本了解。这项研究带来的科学知识的进步将刺激具有优异热稳定性和化学稳定性的固态钠电池的发展。这种电池可以作为新的替代低成本电源，用于各种储能应用。通过这个项目，国际和平研究所将促进当地小学生、初中生和高中生、本科生和研究生之间对科学话语的参与，特别是在能源材料领域。PI将把这项研究整合到高中AP课程中，并将开发一个以电池为主题的暑期工作坊，特别是为中小学女孩提供科学和工程项目的实践经验。该项目的科学和教育价值将推动储能技术的前沿，促进科学和工程研究的多样性，并解决STEM领域的性别差距。技术总结在已知的钠电池系统固体电解质中，钠离子超级导体，即NASICON，由于其高的钠离子电导率和优异的电化学和热稳定性，是最有前途的钠离子导电陶瓷固体电解质之一。同时，金属钠因其较低的电化学电位和较高的理论比容量而被认为是钠电池的“圣杯”负极材料。然而，固态钠电池用NASICON电解液与金属钠负极配对后，在电化学循环过程中会产生较大的NASICON/钠界面电阻和不均匀的树枝状钠沉积。在这个职业项目中，NASICON的界面化学将通过原子层沉积的各种超薄金属氧化物涂层来调节。这项研究将探讨NASICON表面氧化物涂层的组成、结晶度、形貌和微结构对金属钠早期电化学润湿性和界面上的钠离子传输起关键作用的假设，这些影响界面阻抗、钠的成核/生长过程和电化学特性。这项研究可以利用更可持续、自然丰富和低成本的钠资源，实现超越锂技术的飞跃。与锂电池相比，钠电池的成本更低，这将使其非常适合大规模储能应用。该研究所将把这一研究计划纳入各种教育和外展活动，以广泛传播知识/研究成果，促进工程研究的多样性，并解决STEM领域的性别差距。教育部分主要包括以下几个方面：(1)通过为本科生和研究生开发新的课程和研究项目，将这项研究纳入教学；(2)将这项研究整合到当地高中AP课程中；(3)为中小学生开发暑期工作坊“电池仙境”，以获得科学和工程项目的实践经验。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYBeyond lithium-ion batteries, sodium-ion batteries show great potential for transportation electrification and large-scale energy storage owing to their analogous battery chemistry, high abundance of sodium sources, low cost of sodium raw materials, and accessibility. Meanwhile, solid-state batteries, which employ nonflammable solid electrolytes to replace the flammable liquid ones, offer a revolutionary solution to mitigate fire hazards that have hobbled the advances of battery technology. One of the major challenges in the development of high-performance solid-state sodium batteries lies in the large interfacial resistance between the sodium ceramic solid electrolyte and the electrode material. This CAREER award project, jointly supported by the Ceramics program in the Division of Materials Research, and the the Established Program to Stimulate Competitive Research (EPSCoR), addresses the critical interfacial challenges facing between a sodium metal electrode and the sodium ceramic solid electrolyte through regulating the electrolyte surface properties. The PI and her research group seek fundamental understanding on the interfacial structure-composition-property relationship of the sodium ceramic solid electrolyte. The advancement of scientific knowledge enabled by this research will stimulate the development of solid-state sodium batteries with superior thermal and chemical stability. Such batteries can serve as new alterative low-cost power sources for diverse energy storage applications. Through this project the PI will promote engagement between local elementary, middle and high school students, undergraduate and graduate students in scientific discourse, particularly in the field of energy materials. The PI will integrate this research into high school AP curriculum and will develop a battery-themed summer workshop, especially for elementary and middle school girls to get hands-on experience for science and engineering projects. The scientific and educational merits of this project will advance the frontiers of energy storage technologies, promote the diversity in science and engineering research, and tackle the gender gap in STEM fields.TECHNICAL SUMMARYAmong the known solid electrolytes for sodium battery systems, sodium-ion superionic conductor, namely NASICON, is one of the most promising sodium-ion conducting ceramic solid electrolytes owing to its high sodium-ion conductivity and excellent electrochemical and thermal stabilities. Meanwhile, sodium metal is considered as the “holy grail” anode material for sodium batteries because of its low electrochemical potential and high theoretical specific capacity. However, the pairing of NASICON electrolyte with metallic sodium anode for solid-state sodium batteries gives large NASICON/sodium interfacial resistance and nonuniform dendritic sodium deposition over electrochemical cycling. In this CAREER project, the interface chemistry of NASICON will be regulated by a variety of ultrathin metal oxide coatings via atomic layer deposition. This research will investigate the hypothesis that the composition, crystallinity, morphology, and microstructure of the oxide coating on NASICON play critical roles in the early-stage electrochemical wettability of sodium metal and the sodium-ion transport across the interface, which affect the interfacial impedance, the sodium nucleation/growth process, and the electrochemical characteristics. This research can take a leap beyond the lithium technology by utilizing the much more sustainable, natural abundant and low-cost sodium resources. The reduced cost of sodium batteries compared to the lithium systems will make them highly desirable for large-scale energy storage application. The PI will integrate this research program into a variety of educational and outreach activities to broadly disseminate the knowledge/research findings, to promote the diversity in engineering research, and to tackle the gender gap in STEM fields. The education components mainly include the following aspects: (1) incorporating this research into teaching by developing new course curriculums and research projects for undergraduate and graduate students; (2) integrating this research into local high school AP curriculum; (3) developing summer workshop “Battery Wonderland” for elementary and middle school girls to get hands-on experience for science and engineering projects.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.