In-Situ Formation of Ternary Sulfide-rich Interphases for Stabilizing Lithium Deposition in Lithium-sulfur Batteries

以负担得起的成本储存能源已成为能源部门面临的挑战性问题之一，对于从电动汽车到可再生能源的电网储存等广泛应用至关重要。锂硫电池是最有前景的下一代电池技术之一，因为锂和硫表现出比目前锂离子电池使用的电极材料高出十倍的电荷储存能力。此外，硫磺对环境无害，价格低廉，在安全的国内供应链上随处可得。尽管有这些优势，但锂硫电池的商业应用受到循环寿命较差的阻碍。本项目致力于通过系统地调整锂硫电池负极的表面组成和性能来开发一种有效的策略来提高锂硫电池的循环寿命。利用各种计算、电化学和材料表征技术研究界面材料改性阳极层对循环寿命的影响。这将是实现实际相关的高能量密度和延长循环寿命的锂硫电池的关键一步。这项工作还有望对硫化物的独特化学产生新的见解，硫化物在不同领域有应用，包括光伏、催化和有机半导体。该项目还将在全球重要的清洁能源领域为研究生和本科生以及历史上代表性不足的社区大学生和教师提供广泛的跨学科培训，包括无机化学、固态物理、电化学系统和材料科学与工程。硫的独特化学及其形成可溶于液体电解液的多硫化物中间体的趋势深刻地影响了锂-S电池锂-金属表面形成的固体-电解液界面层。本项目致力于开发一种系统有效的策略来调整SEI层的成分，以提高锂-S电池的镀锂和剥离的可逆性。电解液和阴极添加剂将与生成的多硫化物中间体协同工作，在锂-金属表面形成稳定的SEI层。具体地说，高锂离子电导率的LiXS三元硫化物将被作为原位工程SEI组分进行研究，其中X是一种高氧化态阳离子，其元素的电负性低于硫。假设X-S键的性质将在决定修饰的SEI层的性质，从而决定所测量的锂循环效率方面起关键作用。原位改性SEI层对电化学性能的影响将通过测定锂库存损失率，与实际相关的无阳极全电池(有限的锂库存)和袋式电池(有限的电解液供应)进行评估。通过现场设计富含硫化物的锂离子电池，并仔细应用计算和材料表征技术，该项目旨在(I)确定锂-S电池中稳定的离子注入成分及其制造方法，(Ii)建立对离子注入层对锂电镀和剥离可逆性影响的组成-结构-性能关系的基本了解，以及(Iii)展示在现实电池设计和测试条件下，离子注入修饰对电化学性能的影响。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智力优势和更广泛的影响审查标准进行评估，认为值得支持。

Energy storage at an affordable cost has emerged as one of the challenging issues for the energy sector, being critical for a wide range of applications ranging from electric vehicles to grid storage of renewable energies. Lithium-sulfur batteries are one the most promising next-generation battery technologies, as lithium and sulfur exhibit charge-storage capacity ten times higher than that of the electrode materials used in current lithium-ion batteries. Also, sulfur is environmentally benign, inexpensive, and widely available with secure domestic supply chains. Despite these advantages, the commercial adoption of lithium-sulfur batteries is hobbled by their poor cycle life. This project focuses on developing an effective strategy for improving the cycle life of lithium-sulfur batteries by systematically tuning the surface composition and properties of the anode. The effect of the modified interface material anode layer on the cycle life will be investigated with various computational, electrochemical, and materials characterization techniques. This will be a crucial step towards realizing practically relevant lithium-sulfur batteries with high energy density and extended cycle life. This work is also expected to yield new insights into the unique chemistry of sulfur compounds, which find applications in diverse areas, including photovoltaics, catalysis, and organic semiconductors. The project will also provide a broad interdisciplinary training to graduate and undergraduate students as well as historically underrepresented community college students and teachers in the globally important area of clean energy, encompassing inorganic chemistry, solid-state physics, electrochemical systems, and materials science and engineering.The unique chemistry of sulfur and its tendency to form polysulfide intermediates that are soluble in the liquid electrolyte profoundly impact the solid-electrolyte interphase (SEI) layer formed on lithium-metal surface in Li-S batteries. This project focuses on developing a systematic and effective strategy for tailoring the composition of the SEI layer to improve the reversibility of lithium plating and stripping in Li-S batteries. Electrolyte and cathode additives will be identified that work in tandem with the generated polysulfide intermediates to form a stabilizing SEI layer on lithium-metal surface. Specifically, high Li-ion conductivity LiXS ternary sulfides will be investigated as in-situ engineered SEI components, where X is a high-oxidation state cation of an element less electronegative than sulfur. It is hypothesized that the nature of X-S bond would play a critical role in determining the properties of the modified SEI layer, and consequently, the measured lithium cycling efficiency. The impact of the in-situ modified SEI layers on electrochemical performance will be assessed with practically relevant anode-free full cells (limited lithium inventory) and pouch cells (limited electrolyte supply) by determining the lithium inventory loss rates. With the in-situ engineering of a sulfide-rich lithium SEI and careful application of computational and materials characterization techniques, the project aims to (i) identify stabilizing SEI components in Li-S batteries and methods of fabricating them, (ii) establish a fundamental understanding of the composition-structure-property relationships that underlie the effect of SEI layer on the reversibility of lithium plating and stripping, and (iii) demonstrate the impact of SEI modification on electrochemical performance under realistic cell design and testing conditions.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.