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Title: Local Structure Evolution and Modes of Charge Storage in Secondary Li–FeS 2 Cells

Abstract

In the pursuit of high-capacity electrochemical energy storage, a promising domain of research involves conversion reaction schemes, wherein electrode materials are fully transformed during charge and discharge. There are, however, numerous difficulties in realizing theoretical capacity and high rate capability in many conversion schemes. Here we employ operando studies to understand the conversion material FeS2, focusing on the local structure evolution of this relatively reversible material. X-ray absorption spectroscopy, pair distribution function analysis, and first-principles calculations of intermediate structures shed light on the mechanism of charge storage in the Li-FeS2 system, with some general principles emerging for charge storage in chalcogenide materials. Focusing on second and later charge/discharge cycles, we find small, disordered domains that locally resemble Fe and Li2S at the end of the first discharge. Upon charge, this is converted to a Li-Fe-S composition whose local structure reveals tetrahedrally coordinated Fe. With continued charge, this ternary composition displays insertion extraction behavior at higher potentials and lower Li content. The finding of hybrid modes of charge storage, rather than simple conversion, points to the important role of intermediates that appear to store charge by mechanisms that more closely resemble intercalation.


Citation Formats

Butala, Megan M., Mayo, Martin, Doan-Nguyen, Vicky V. T., Lumley, Margaret A., Göbel, Claudia, Wiaderek, Kamila M., Borkiewicz, Olaf J., Chapman, Karena W., Chupas, Peter J., Balasubramanian, Mahalingam, Laurita, Geneva, Britto, Sylvia, Morris, Andrew J., Grey, Clare P., and Seshadri, Ram. Local Structure Evolution and Modes of Charge Storage in Secondary Li–FeS 2 Cells. United States: N. p., 2017. Web. doi:10.1021/acs.chemmater.7b00070.
Butala, Megan M., Mayo, Martin, Doan-Nguyen, Vicky V. T., Lumley, Margaret A., Göbel, Claudia, Wiaderek, Kamila M., Borkiewicz, Olaf J., Chapman, Karena W., Chupas, Peter J., Balasubramanian, Mahalingam, Laurita, Geneva, Britto, Sylvia, Morris, Andrew J., Grey, Clare P., & Seshadri, Ram. Local Structure Evolution and Modes of Charge Storage in Secondary Li–FeS 2 Cells. United States. doi:10.1021/acs.chemmater.7b00070.
Butala, Megan M., Mayo, Martin, Doan-Nguyen, Vicky V. T., Lumley, Margaret A., Göbel, Claudia, Wiaderek, Kamila M., Borkiewicz, Olaf J., Chapman, Karena W., Chupas, Peter J., Balasubramanian, Mahalingam, Laurita, Geneva, Britto, Sylvia, Morris, Andrew J., Grey, Clare P., and Seshadri, Ram. Mon . "Local Structure Evolution and Modes of Charge Storage in Secondary Li–FeS 2 Cells". United States. doi:10.1021/acs.chemmater.7b00070.
@article{osti_1376702,
title = {Local Structure Evolution and Modes of Charge Storage in Secondary Li–FeS 2 Cells},
author = {Butala, Megan M. and Mayo, Martin and Doan-Nguyen, Vicky V. T. and Lumley, Margaret A. and Göbel, Claudia and Wiaderek, Kamila M. and Borkiewicz, Olaf J. and Chapman, Karena W. and Chupas, Peter J. and Balasubramanian, Mahalingam and Laurita, Geneva and Britto, Sylvia and Morris, Andrew J. and Grey, Clare P. and Seshadri, Ram},
abstractNote = {In the pursuit of high-capacity electrochemical energy storage, a promising domain of research involves conversion reaction schemes, wherein electrode materials are fully transformed during charge and discharge. There are, however, numerous difficulties in realizing theoretical capacity and high rate capability in many conversion schemes. Here we employ operando studies to understand the conversion material FeS2, focusing on the local structure evolution of this relatively reversible material. X-ray absorption spectroscopy, pair distribution function analysis, and first-principles calculations of intermediate structures shed light on the mechanism of charge storage in the Li-FeS2 system, with some general principles emerging for charge storage in chalcogenide materials. Focusing on second and later charge/discharge cycles, we find small, disordered domains that locally resemble Fe and Li2S at the end of the first discharge. Upon charge, this is converted to a Li-Fe-S composition whose local structure reveals tetrahedrally coordinated Fe. With continued charge, this ternary composition displays insertion extraction behavior at higher potentials and lower Li content. The finding of hybrid modes of charge storage, rather than simple conversion, points to the important role of intermediates that appear to store charge by mechanisms that more closely resemble intercalation.},
doi = {10.1021/acs.chemmater.7b00070},
journal = {Chemistry of Materials},
number = 7,
volume = 29,
place = {United States},
year = {Mon Mar 27 00:00:00 EDT 2017},
month = {Mon Mar 27 00:00:00 EDT 2017}
}