Title: A Multidimensional Operando Study Showing the Importance of the Electrode Macrostructure in Lithium Sulfur Batteries

Abstract

Lithium sulfur batteries are one of the most promising next-generation energy storage technologies, because of their impressive theoretical energy density, low materials cost, and relative safety. However, incomplete understanding of their underlying operation mechanisms has hindered their further development and commercialization. In this work, to gain a better understanding of the operation mechanisms in the lithium sulfur battery, three macroscopically different (woven and nonwoven) and microscopically similar (made from the same carbon fibers) free-standing carbon felts are used as the conductive matrices to show how the macrostructure influences the redox reactions and the electrochemical performance. Additionally, an operando radiography and simultaneous in situ electrochemical impedance spectroscopy study are performed to highlight the differences of the carbon hosts and how they compare electrochemically in a lithium sulfur battery. The electrochemical results show that the carbon host with a more open structure results in increased capacity as well as a higher diffusion coefficient. The operando radiography shows that the open structures are more conducive to efficient redox reactivity in forming solid sulfur species, mostly in the form of elongated needlelike structures identified as β-S8, near the end of charge, which is corroborated by the impedance data. The data also reveal a “breathing”more » mechanism, where the polysulfides are pushed to the edges during discharge and pulled back during charge. Furthermore, it is also revealed that the “breathing” process is a limiting factor in the high rate performance. Overall, this study shows that there is a close relationship between the macrostructure of the carbon matrix and the electrochemical performance of the sulfur cathode.« less

Authors:

Jafta, Charl J.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-9773-6799"

Hilger, André ^[2]; Sun, Xiao-Guang  ^[1];

• Search DOE PAGES for author "Sun, Xiao-Guang"
• Search DOE PAGES for ORCID "0000-0001-8451-3011"

Geng, Linxiao  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-2869-8717"

Li, Mengya  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-9581-4044"

Risse, Sebastian ^[3]; Belharouak, Ilias  ^[4];

• Search DOE PAGES for author "Belharouak, Ilias"
• Search DOE PAGES for ORCID "0000-0002-3985-0278"

Manke, Ingo  ^[2]

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• Search DOE PAGES for ORCID "0000-0001-9795-5345"

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+ Show Author Affiliations

1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Institute of Applied Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin (Germany)
3. Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin (Germany)
4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States). Bredesen Center for Interdisciplinary Research and Graduate Education

Publication Date:

Tue Jun 23 00:00:00 EDT 2020

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES), Materials Sciences and Engineering Division

OSTI Identifier:

1649254

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

ACS Applied Energy Materials

Additional Journal Information:

Journal Volume: 3; Journal Issue: 7; Journal ID: ISSN 2574-0962

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

25 ENERGY STORAGE; Redox reactions; sulfur; carbon fiber; chemical structure; batteries; lithium polysulfide batteries; macrostructure; radiography; EIS; breathing mechanism