Effect of Metal d Band Position on Anion Redox in Alkali-Rich Sulfides.

Autor: Kim SS; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States., Agyeman-Budu DN; Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States., Zak JJ; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States., Andrews JL; Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States., Li J; Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, United States., Melot BC; Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States.; Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089, United States., Nelson Weker J; Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States., See KA; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Jazyk: angličtina
Zdroj: Chemistry of materials : a publication of the American Chemical Society [Chem Mater] 2024 Jun 21; Vol. 36 (13), pp. 6454-6463. Date of Electronic Publication: 2024 Jun 21 (Print Publication: 2024).
DOI: 10.1021/acs.chemmater.4c00490
Abstrakt: New energy storage methods are emerging to increase the energy density of state-of-the-art battery systems beyond conventional intercalation electrode materials. For instance, employing anion redox can yield higher capacities compared with transition metal redox alone. Anion redox in sulfides has been recognized since the early days of rechargeable battery research. Here, we study the effect of d-p overlap in controlling anion redox by shifting the metal d band position relative to the S p band. We aim to determine the effect of shifting the d band position on the electronic structure and, ultimately, on charge compensation. Two isostructural sulfides LiNaFeS 2 and LiNaCoS 2 are directly compared to the hypothesis that the Co material should yield more covalent metal-anion bonds. LiNaCoS 2 exhibits a multielectron capacity of ≥1.7 electrons per formula unit, but despite the lowered Co d band, the voltage of anion redox is close to that of LiNaFeS 2 . Interestingly, the material suffers from rapid capacity fade. Through a combination of solid-state nuclear magnetic resonance spectroscopy, Co and S X-ray absorption spectroscopy, X-ray diffraction, and partial density of states calculations, we demonstrate that oxidation of S nonbonding p states to S 2 2- occurs in early states of charge, which leads to an irreversible phase transition. We conclude that the lower energy of Co d bands increases their overlap with S p bands while maintaining S nonbonding p states at the same higher energy level, thus causing no alteration in the oxidation potential. Further, the higher crystal field stabilization energy for octahedral coordination over tetrahedral coordination is proposed to cause the irreversible phase transition in LiNaCoS 2 .
Competing Interests: The authors declare no competing financial interest.
(© 2024 The Authors. Published by American Chemical Society.)
Databáze: MEDLINE
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