Collaborative Research: Understanding Sulfur-Carbon-Solid Electrolyte Interface of Lithium/Sulfur Solid-State Batteries

近年来，使用电动汽车（ev）作为一种更可持续的交通方式已经取得了重大进展。为电动汽车提供动力的可充电电池对电动汽车的行驶里程、安全性、成本都有很大的影响，因此要想提高电动汽车的普及率，就必须不断创新。锂/硫（Li/S）电池由锂金属阳极和硫阴极组成，是电动汽车应用的一个很有前途的候选者，因为在给定重量的电动汽车电池下，与传统锂离子电池相比，它的行驶距离可能长5倍。开发可靠、安全的锂/S电池面临的主要挑战是：1)需要缓解与锂多硫化物化合物相关的问题，锂多硫化物是电池运行过程中在有机液体电解质中形成的；2)用作电解质的易燃离子导体。Li/S固态电池是一种很有前途的系统，可以克服这些问题，因为它使用的是一种不易燃的固态电解质，比液体电解质更能防止多硫化物的形成。然而，由于对电极-固体电解质界面的理解不足，Li/S固态电池的能量存储/传输性能较差。本项目将对Li/S固态电池的界面进行基础研究，采用先进的材料表征方法，并实施合理的电极设计来应对这些挑战。该项目的成果将创造新的知识，使能源存储解决方案能够满足美国实现全球汽车行业脱碳和塑造可持续能源未来的使命。通过亚利桑那州立大学和密歇根大学安娜堡分校之间的无缝合作，制定了全面的教育和劳动力发展计划。通过这项研究项目培养研究生和本科生将大大有助于两所大学成为能源技术温床的使命。该项目的总体目标是提高对采用石榴石型锂镧氧化锆（Li7La3Zr2O12， LLZO）作为固体电解质的Li/S复合阴极中电化学过程的理解。研究将集中于：1)利用模型系统、电分析技术和非原位x射线分析提高了对Li/S复合阴极反应机理的理解；2)阐明了影响硫电化学过程的基本热力学和动力学参数；3)研究了硫/固态电解质复合阴极中组分的粒度、形貌、表面性质和质量负载等设计参数。通过合作研究团队在锂/硫电池化学、固态电池技术和基于同步加速器的原位/operando表征方面的专业知识，该项目将为研究和设计可持续的下一代储能系统提供全面的方法。该项目的成果将导致S-LLZO复合阴极的创新设计，这有利于快速和可持续的电化学过程。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。

In recent years, there has been a significant movement towards using electric vehicles (EVs) as a more sustainable form of transportation. Continuous innovation of rechargeable batteries that supply power to an electric motor is required to boost the adoption of EVs since the battery significantly affects the driving range, safety, and cost of EVs. A lithium/sulfur (Li/S) battery consisting of a lithium metal anode and sulfur cathode is a promising candidate for EV applications as it has the potential for a five-times longer driving distance at a given weight of the EV battery compared to conventional lithium-ion batteries. The major challenges towards the development of reliable and safe Li/S batteries are 1) the need to mitigate problematic issues associated with chemical compounds called lithium polysulfides, which are formed in the organic liquid electrolyte during battery operation, and 2) the flammable ionic conductor used as electrolyte. A Li/S solid-state battery is a promising system for overcoming these issues because it uses a solid-state electrolyte which is non-flammable and can prevent polysulfide formation better than liquid electrolytes. However Li/S solid-state batteries suffer from poor energy storage/delivery performance due to an insufficient understanding of the electrode-solid electrolyte interface. This project will conduct fundamental studies on the interfaces in Li/S solid-state batteries, advanced materials characterization methods, and implement rational electrode design to address these challenges. The results from this project will create new knowledge that can enable energy storage solutions to meet the U.S.’s mission toward decarbonizing the global automotive sector and shaping the sustainable energy future. Comprehensive education and workforce development plans are laid out through a seamless partnership between Arizona State University and the University of Michigan Ann Arbor. Training graduate and undergraduate students via this research project will significantly contribute to the mission of both universities mission to become a hotbed of energy technologies.The overarching goal of this project is to improve the understanding of the electrochemical processes taking place in Li/S composite cathodes employing garnet-type lithium lanthanum zirconium oxide (Li7La3Zr2O12, LLZO) as a solid electrolyte. The research will focus on: 1) Obtaining an improved understanding of the reaction mechanisms in Li/S composite cathodes using model systems, electroanalytical techniques, and in operando/ex-situ X-ray analyses, 2) Elucidation of fundamental thermodynamic and kinetic parameters influential in the electrochemical processes of sulfur, and 3) Investigation of design parameters such as particle size, morphology, surface properties, and mass loading of components in the sulfur/solid state electrolyte composite cathode. Enabled by the collaborative research team’s expertise in Li/S cell chemistry, solid-state battery technology, and synchrotron-based in-situ/operando characterization, this project will result in a comprehensive methodology for investigating and designing sustainable, next-generation energy storage systems. The results of the project will lead to the innovative design of S-LLZO composite cathodes, which is favorable for fast and sustainable electrochemical processes.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.