A formal Fe^III/V redox couple in an intercalation electrode.

IF 38.5 1区材料科学 Q1 CHEMISTRY, PHYSICAL

Nature Materials Pub Date : 2025-10-15 DOI:10.1038/s41563-025-02356-x

Hari Ramachandran, Edward W Mu, Eder G Lomeli, Augustin Braun, Masato Goto, Kuan H Hsu, Jue Liu, Zhelong Jiang, Kipil Lim, Grace M Busse, Brian Moritz, Joshua J Kas, John Vinson, John J Rehr, Jungjin Park, Iwnetim I Abate, Yuichi Shimakawa, Edward I Solomon, Wanli Yang, William E Gent, Thomas P Devereaux, William C Chueh

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引用次数: 0

Abstract

Iron redox cycling between low-valent oxidation states of Fe^II and Fe^III drives crucial processes in nature. The Fe^II/III redox couple charge compensates the cycling of lithium iron phosphate, a positive electrode (cathode) for lithium-ion batteries. High-valent iron redox couples, involving formal oxidation higher than Fe^III, could deliver higher electrochemical potentials and energy densities. However, because of the instability of high-valent Fe electrodes, they have proven difficult to probe and exploit in intercalation systems. Here we report and characterize a formal Fe^III/V redox couple by revisiting the charge compensation mechanism of (de)lithiation in Li₄FeSbO₆. Valence-sensitive experimental and computational core-level spectroscopy reveal a direct transition from Fe^III (3d⁵) to a negative-charge-transfer Fe^V (3d⁵L²) ground state on delithiation, without forming Fe^IV, or oxygen dimers. We identify that the cation ordering in Li₄FeSbO₆ drives a templated phase transition to stabilize the unique Fe^V species and demonstrate that disrupting cation ordering suppresses the Fe^III/V redox couple. Exhibiting resistance to calendar aging, high operating potential and low voltage hysteresis, the Fe^III/V redox couple in Li₄FeSbO₆ provides a framework for developing sustainable, Fe-based intercalation cathodes for high-voltage applications.

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嵌入电极中的FeIII/V氧化还原对。

铁在FeII和FeIII的低价氧化态之间的氧化还原循环驱动着自然界的关键过程。FeII/III氧化还原偶电荷补偿磷酸铁锂的循环，磷酸铁锂是锂离子电池的正极（负极）。高价铁氧化还原偶比FeIII的形式氧化程度更高，可以提供更高的电化学电位和能量密度。然而，由于高价铁电极的不稳定性，它们已被证明难以在插层体系中探测和利用。在这里，我们通过重新考察Li4FeSbO6中（de）锂化的电荷补偿机制，报道并表征了一种形式的FeIII/V氧化还原对。价敏感的实验和计算核能级光谱揭示了从FeIII （3d5）到负电荷转移FeV （3d5L2）基态的直接转变，而不形成FeIV或氧二聚体。我们发现Li4FeSbO6中的阳离子顺序驱动模板化相变以稳定独特的FeV物种，并证明破坏阳离子顺序抑制FeIII/V氧化还原对。Li4FeSbO6中的FeIII/V氧化还原对具有抗日历老化、高工作电位和低电压滞后的特点，为开发可持续的、用于高压应用的铁基插入阴极提供了框架。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Nature Materials 工程技术-材料科学：综合

CiteScore

62.20

自引率

0.70%

发文量

221

审稿时长

3.2 months

期刊介绍： Nature Materials is a monthly multi-disciplinary journal aimed at bringing together cutting-edge research across the entire spectrum of materials science and engineering. It covers all applied and fundamental aspects of the synthesis/processing, structure/composition, properties, and performance of materials. The journal recognizes that materials research has an increasing impact on classical disciplines such as physics, chemistry, and biology. Additionally, Nature Materials provides a forum for the development of a common identity among materials scientists and encourages interdisciplinary collaboration. It takes an integrated and balanced approach to all areas of materials research, fostering the exchange of ideas between scientists involved in different disciplines. Nature Materials is an invaluable resource for scientists in academia and industry who are active in discovering and developing materials and materials-related concepts. It offers engaging and informative papers of exceptional significance and quality, with the aim of influencing the development of society in the future.