Chemical Bonding in Redox-Active Oxyfluorides

氧化还原插层反应是指电子（负电荷）从一个化学结构转移到另一个化学结构的反应。在固体材料中，这些反应对于创造电池技术至关重要，目前正处于改变人类移动性的尖端。理想情况下，新的电极材料允许电荷的大变化，从而最大限度地提高能量储存，但这些变化也必须是可逆的，以实现广泛的循环和长电池寿命。该项目由美国国家科学基金会材料研究部固态和材料化学项目支持，旨在全面描述氟化氧材料中的化学键，氟化氧材料正在成为高能量密度锂离子电池阴极中纯氧化物的替代品。研究人员调查了氟离子在操纵潜在氧化还原反应中的作用，特别注意它在电荷补偿中的参与。该研究不仅评估了氟化氧材料作为实用电池电极的可行性和设计规则，而且扩大了现有的无机结晶固体键合的一般理论。这项研究有可能为发现和设计具有突破性性能的混合阴离子材料提供信息，甚至超出电池应用范围。该研究课题为教育计划提供了动力，该计划的统一目标是引导学生走向能源应用，这是就业市场的一个增长和需求刚刚开始的领域。卡巴纳教授的教育和推广活动涵盖从小学到研究生院，从地方机构到国家活动，重点是针对西班牙裔社区成员的多样性。技术概述：当达到高氧化态时，过渡金属氧化物作为电池阴极的容量达到最大，但这些氧化态不稳定，导致不可逆性和失效。最近已经探索了氟氧化物作为替代品，但阴离子之间产生的协同作用仍有待确定，特别是当金属达到高形式氧化态时卤化物的作用。该项目由美国国家科学基金会材料研究部固态和材料化学项目资助，利用并扩展了x射线光谱学的方法，以揭示氧化还原补偿中金属和阴离子的负荷平衡。这项研究涵盖了晚期金属的相，因为众所周知，晚期金属的高形式氧化态对阴离子的化学要求最为严格，同时也与电池的现代趋势有关。这项研究旨在定义新的途径来定制材料，以有效和可逆地存储大量电化学能量，建立新的化学键知识，这有可能超越目前化学和电池研究的界限。一个紧密结合的教育组成部分促进材料化学和能源主题的下一代。它包括拓展到当地小学和一个关于电化学研究前沿的全国夏季研讨会。研究人员还招募本科生进行支持这项研究的项目，包括通过与芝加哥伊利诺伊大学的西班牙裔组织合作。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。

NON-TECHNICAL SUMMARYRedox intercalation reactions are reactions during which electrons (negative charges) are transferred from one chemical building to a different one. In solid materials these reactions are essential to create battery technologies currently on the cusp of transforming human mobility. Ideally new electrode materials allow large changes of charge, which maximizes energy storage, but these changes must also be reversible for extensive cycling and long battery lifetimes. This project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, seeks to build comprehensive descriptions of the chemical bond in oxyfluoride materials that are emerging as alternatives to pure oxides in cathodes for Li-ion batteries with high energy density. The researchers investigate the role of fluoride ions to manipulate the underlying redox reaction, with especial attention to its participation in charge compensation. The research not only assesses the viability and design rules of oxyfluoride materials as practical battery electrodes, but also amplifies existing general theories of bonding in inorganic crystalline solids. The research has the potential to inform the discovery and design of mixed-anion materials with groundbreaking properties, even beyond battery applications. The research topic provides the driver for an educational plan with the unified goal to guide students toward energy applications, an area of the job market where growth and demand are still just onsetting. Professor Cabana’s portfolio of education and outreach activities spans from elementary to graduate school, from local institutions to national events, with an emphasis in diversity by targeting members of Hispanic communities.TECHNICAL SUMMARYThe capacity of transition metal oxides as battery cathodes is maximized when high oxidation states can be achieved, but these states are not stable, leading to irreversibility and failure. Oxyfluorides have recently been explored as alternatives, but the resulting synergies between anions remain to be ascertained, particularly the role of the halide when metals reach high formal oxidation states. This project, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, leverages and expands methodologies of X-ray spectroscopy to uncover the balance of burden of metals and anions in redox compensation of oxyfluorides. The research spans to phases with late metals because their high formal oxidation states are known to place the most stringent chemical demand on the anions, while also providing relevance to modern trends in batteries. This research aims to define fresh avenues to tailor materials to effectively and reversibly store large amounts of electrochemical energy, building new knowledge of the chemical bond that has the potential to transcend current boundaries of both chemistry and battery research. A tightly integrated educational component promotes materials chemistry and energy topics among the next generations. It includes outreach to local elementary schools and a national Summer workshop on the frontiers of research in electrochemistry. The researchers also recruit undergraduates to conduct projects in support of this research, including through partnerships with Hispanic organizations at the University of Illinois at Chicago.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.