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Multielectron, Cation and Anion Redox in Lithium-Rich Iron Sulfide Cathodes

Hansen, Charles J. and Zak, Joshua J. and Martinolich, Andrew J. and Ko, Jesse S. and Bashian, Nicholas H. and Kaboudvand, Farnaz and Van der Ven, Anton and Melot, Brent C. and Weker, Johanna Nelson and See, Kimberly A. (2020) Multielectron, Cation and Anion Redox in Lithium-Rich Iron Sulfide Cathodes. Journal of the American Chemical Society, 142 (14). pp. 6737-6749. ISSN 0002-7863. doi:10.1021/jacs.0c00909.

[img] PDF (Experimental details on Na2S and electrolyte preparation, details on the electrochemical cell for operando XRD, list of potential impurities in Li2FeS2 and LiNaFeS2, synchrotron XRD of Li2FeS2 and LiNaFeS2 with corresponding Rietveld refinements shown...) - Supplemental Material
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Conventional Li-ion cathodes store charge by reversible intercalation of Li coupled to metal cation redox. There has been increasing interest in new materials capable of accommodating more than one Li per transition-metal center, thereby yielding higher charge storage capacities. We demonstrate here that the lithium-rich layered iron sulfide Li₂FeS₂ as well as a new structural analogue, LiNaFeS₂, reversibly store ≥1.5 electrons per formula unit and support extended cycling. Ex situ and operando structural and spectroscopic data indicate that delithiation results in reversible oxidation of Fe²⁺ concurrent with an increase in the covalency of the Fe–S interactions, followed by reversible anion redox: 2 S²⁻/(S₂)²⁻. S K-edge spectroscopy unequivocally proves the contribution of the anions to the redox processes. The structural response to the oxidation processes is found to be different in Li₂FeS₂ in contrast to that in LiNaFeS₂, which we suggest is the cause for capacity fade in the early cycles of LiNaFeS₂. The materials presented here have the added benefit of avoiding resource-sensitive transition metals such as Co and Ni. In contrast to Li-rich oxide materials that have been the subject of so much recent study and that suffer capacity fade and electrolyte degradation issues, the materials presented here operate within the stable potential window of the electrolyte, permitting a clearer understanding of the underlying processes.

Item Type:Article
Related URLs:
URLURL TypeDescription
Hansen, Charles J.0000-0003-4981-9087
Zak, Joshua J.0000-0003-3793-7254
Martinolich, Andrew J.0000-0002-7866-9594
Ko, Jesse S.0000-0001-6965-4174
Bashian, Nicholas H.0000-0001-9984-2539
Kaboudvand, Farnaz0000-0002-8366-0041
Melot, Brent C.0000-0002-7078-8206
Weker, Johanna Nelson0000-0001-6856-3203
See, Kimberly A.0000-0002-0133-9693
Additional Information:© 2020 American Chemical Society. Received: January 23, 2020; Published: March 30, 2020. This work was supported as part of the Center for Synthetic Control Across Length-scales for Advancing Rechargeables (SCALAR), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award No. DE-SC0019381. C.J.H. was supported by a Beckman-Gray Graduate Student Fellowship made possible by the Arnold and Mabel Beckman Foundation. J.J.Z. acknowledges support from the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1745301. A.J.M. acknowledges a postdoctoral fellowship from the Resnick Sustainability Institute at Caltech. Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-76SF00515. The authors thank Prof. Ryan G. Hadt and Sarah C. Bevilacqua for useful discussions.
Group:Resnick Sustainability Institute
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0019381
Arnold and Mabel Beckman FoundationUNSPECIFIED
NSF Graduate Research FellowshipDGE-1745301
Resnick Sustainability InstituteUNSPECIFIED
Department of Energy (DOE)DE-AC02-06CH11357
Department of Energy (DOE)DE-AC02-76SF00515
Issue or Number:14
Record Number:CaltechAUTHORS:20200330-101312532
Persistent URL:
Official Citation:Multielectron, Cation and Anion Redox in Lithium-Rich Iron Sulfide Cathodes. Charles J. Hansen, Joshua J. Zak, Andrew J. Martinolich, Jesse S. Ko, Nicholas H. Bashian, Farnaz Kaboudvand, Anton Van der Ven, Brent C. Melot, Johanna Nelson Weker, and Kimberly A. See. Journal of the American Chemical Society 2020 142 (14), 6737-6749; DOI: 10.1021/jacs.0c00909
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102168
Deposited By: Tony Diaz
Deposited On:30 Mar 2020 17:36
Last Modified:16 Nov 2021 18:09

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