CAREER: Structural Implications of Anion Redox in Li-Rich Sulfide Cathodes for Li-ion Batteries

职业：锂离子电池富锂硫化物阴极中阴离子氧化还原的结构影响

• 批准号: 2340864
• 负责人: Kimberly See
• 金额: $ 81.77万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-02-01 至 2029-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2340864&HistoricalAwards=false
• 关键词: CAREER; Structural; Implications; Anion; Redox

Part 1: Non-Technical SummaryBatteries are energy storage devices that convert chemical energy to electrical energy and are critical technologies to realizing a fully electrified energy infrastructure. The rechargeable batteries that store the most energy per unit mass are lithium ion (Li-ion) batteries. Li-ion batteries store electrons in solid materials composed of transitions metals, like nickel and cobalt, and anions (negatively charged ions), usually oxygen. As electrons are introduced into (removed from) the material, the transition metal is reduced (oxidized) and Li cations are incorporated (removed) so the net charge of the material remains neutral. In conventional materials, the anions are bystander atoms that only act to hold the transition metals together. With this CAREER award, supported jointly by the Solid State and Materials Chemistry program in NSF’s Division of Materials Research and the Electrochemical Systems program in NSF’s Division of Chemical, Bioengineering, Environmental and Transport Systems, the principal investigator and her research group at the California Institute of Technology investigate the possibility to store electrons on both the transition metals and the anions in the material to increase the number of electrons that can be stored. Instead of oxygen, which is very difficult to oxidize, materials with sulfur anions called sulfides are prepared and studied. They change the physical orientation of the anions relative to the transition metal atoms to determine how the material’s structure affects anion oxidation. The research advances the fundamental understanding of anion oxidation and reduction allowing for the design of new materials with high energy densities that leverage both the transition metals and the anions to store electrons. Further, the research uses materials that have abundant resources to promote domestic supply chains of energy storage devices. As part of this CAREER award, the principal investigator also integrates the results of her work and other sustainability-related concepts into the General Chemistry course and develops new outreach modules for high school outreach that are focused on the implementation of research-based inquiry.Part 2: Technical SummaryConventional Li-ion battery cathodes store charge via intercalation chemistry in metal oxides that contain problematic metals like Co and Ni. Intercalation chemistry relies on transition metal redox to provide charge compensation for the (de)intercalation of mobile Li+ and yields, at most, one electron per transition metal. With this CAREER award, the principal investigator studies mechanisms beyond intercalation chemistry, namely anion redox in Li-rich metal sulfides. Anion oxidation in sulfides can yield very high energy densities thanks to the high capacities, despite the low voltage. To develop a fundamental understanding of anion redox in Co- and Ni-free Li-rich sulfides the research is focused on the structural aspects that both control anion redox and are a consequence of anion redox. One approach is to introduce cation vacancies to provide structural flexibility and promote formation of persulfides. Sulfur oxidation usually causes the formation of S-S bonds. It is hypothesized that the absence of cations allows the material to distort to form the S-S bonds. However, the making and breaking of bonds could slow down the charge storage processes, so other efforts include tuning the crystal chemistry and structure to prevent the formation of persulfides and stabilize holes in the S p bands. Additionally, the principal investigator and her research group study the ability of stacking sequences and anion sublattice arrangements to direct anion redox. The materials are characterized using state-of-the-art tools both in-house and at national facilities. The results of the study are digested into vignettes accessible to freshman students in Caltech's General Chemistry course to showcase the direct ties between pioneering research and fundamental chemistry concepts. Plans also include developing, testing, and eventually publishing outreach modules based on investigative learning environments with a theme of battery chemistry research questions.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.

第一部分：电池是将化学能转化为电能的储能装置，是实现完全电气化的能源基础设施的关键技术。每单位质量存储最多能量的可充电电池是锂离子（Li-ion）电池。锂离子电池将电子存储在由过渡金属（如镍和钴）和阴离子（带负电荷的离子）（通常是氧）组成的固体材料中。当电子被引入材料中（从材料中移除）时，过渡金属被还原（氧化），Li阳离子被并入（移除），因此材料的净电荷保持中性。在传统材料中，阴离子是旁观者原子，仅起将过渡金属保持在一起的作用。通过这个职业奖，由NSF材料研究部门的固态和材料化学计划以及NSF化学，生物工程，环境和运输系统部门的电化学系统计划共同支持，加州理工学院的首席研究员和她的研究小组研究了在材料中的过渡金属和阴离子上存储电子的可能性，增加可以储存的电子数量。而不是氧气，这是非常难以氧化，材料与硫阴离子称为硫化物的制备和研究。它们改变阴离子相对于过渡金属原子的物理取向，以确定材料的结构如何影响阴离子氧化。该研究推进了对阴离子氧化和还原的基本理解，允许设计具有高能量密度的新材料，利用过渡金属和阴离子来存储电子。此外，该研究使用资源丰富的材料来促进储能设备的国内供应链。作为该CAREER奖的一部分，首席研究员还将她的工作成果和其他与可持续发展相关的概念整合到普通化学课程中，并为高中外展开发新的外展模块，重点是实施基于研究的探究。第2部分：技术总结传统锂离子电池阴极通过金属氧化物中的嵌入化学来存储电荷，这些金属氧化物含有有问题的金属，如Co和Ni。嵌入化学依赖于过渡金属氧化还原来为移动的Li+的嵌入（脱嵌）提供电荷补偿，并且每个过渡金属产生最多一个电子。凭借这项职业奖，首席研究员研究了嵌入化学之外的机制，即富锂金属硫化物中的阴离子氧化还原。尽管电压低，但由于高容量，硫化物中的阴离子氧化可以产生非常高的能量密度。为了对无钴和镍的富锂硫化物中的阴离子氧化还原有一个基本的了解，研究集中在控制阴离子氧化还原和阴离子氧化还原的结果的结构方面。一种方法是引入阳离子空位以提供结构灵活性并促进过硫化物的形成。硫的氧化通常导致S-S键的形成。假设不存在阳离子允许材料变形以形成S-S键。然而，键的形成和断裂可能会减缓电荷存储过程，因此其他努力包括调整晶体化学和结构，以防止形成过硫化物并稳定Sp带中的空穴。此外，首席研究员和她的研究小组研究堆叠序列和阴离子亚晶格排列直接阴离子氧化还原的能力。这些材料的特点是使用最先进的工具，无论是在内部和国家设施。这项研究的结果被消化到加州理工学院普通化学课程的新生可以访问的小插曲中，以展示开创性研究与基础化学概念之间的直接联系。该奖项反映了NSF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。