Chemical Bonding in Redox-Active Oxyfluorides

非技术概述氧化还原嵌入反应是电子（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，这些反应对于创造目前处于改变人类移动性尖端的电池技术至关重要。理想情况下，新的电极材料允许较大的电荷变化，从而最大限度地提高能量存储，但这些变化也必须是可逆的，以实现广泛的循环和较长的电池寿命。该项目由NSF材料研究部门的固态和材料化学计划支持，旨在建立对氟氧化物材料中化学键的全面描述，这些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。研究人员研究了氟离子在操纵潜在氧化还原反应中的作用，特别注意其参与电荷补偿。这项研究不仅评估了氟氧化物材料作为实用电池电极的可行性和设计规则，而且还扩展了现有的无机晶体固体中键合的一般理论。这项研究有可能为发现和设计具有开创性性能的混合阴离子材料提供信息，甚至超越电池应用。该研究课题为教育计划提供了驱动力，其统一目标是引导学生走向能源应用，这是就业市场的一个领域，增长和需求仍然刚刚开始。卡巴纳教授的教育和推广活动的投资组合涵盖从小学到研究生院，从地方机构到国家活动，重点是通过针对西班牙裔社区的成员的多样性。技术总结当可以实现高氧化态时，过渡金属氧化物作为电池阴极的能力最大化，但这些状态并不稳定，导致不可逆性和失败。氟氧化物最近已被探索作为替代品，但阴离子之间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NSF材料研究部的固态和材料化学计划资助，利用并扩展了X射线光谱学的方法，以揭示氟氧化还原补偿中金属和阴离子的平衡。该研究涵盖了晚期金属的相，因为众所周知，它们的高形式氧化态对阴离子提出了最严格的化学要求，同时也与电池的现代趋势相关。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的电化学能量，建立化学键的新知识，这些知识有可能超越化学和电池研究的当前边界。一个紧密结合的教育组成部分，促进材料化学和能源的话题在下一代。它包括推广到当地小学和电化学研究前沿的国家夏季研讨会。研究人员还招募本科生进行项目，以支持这项研究，包括通过与西班牙裔组织在伊利诺伊大学芝加哥的合作伙伴关系。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

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.