Title: Orientation-Dependent Distortion of Lamellae in a Block Copolymer Electrolyte under DC Polarization

Abstract

Lithium-salt-doped block copolymers have the potential to serve as solid electrolytes in rechargeable batteries with lithium metal anodes. In this work, we use small-angle X-ray scattering (SAXS) to study the structure of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) doped with bis-(trifluoromethylsulfonyl)amine lithium salt (LiTFSI) during direct current (dc) polarization experiments in lithiu-lithium symmetric cells. The block copolymer studied is nearly symmetric in composition, has a total molecular weight of 39 kg mol^-1, and exhibits a lamellar morphology at all studied salt concentrations. When ionic current is passed through the electrolyte, a salt concentration gradient forms that induces a spatial gradient in the domain spacing, d. The dependence of d on distance from the positive electrode, x, was determined experimentally by scanning the incident X-ray beam from one lithium electrode to the other. By studying the two-dimensional (2D) SAXS patterns as a function of azimuthal scattering angle, we find that lamellae with PS/PEO interfaces oriented perpendicular to the flow of ionic current (LAM_⟂) swell and contract to a greater degree than those with interfaces oriented parallel to the current direction (LAM_||). While domains with the LAM_⟂ do not provide direct conducting pathways between the electrodes, our analysis suggests that they play an important rolemore » in establishing the salt concentration gradient necessary for sustaining a large ionic current through greater expansion and contraction.« less

Authors:

Galluzzo, Michael D.  ^[1];

• Search DOE PAGES for author "Galluzzo, Michael D."
• Search DOE PAGES for ORCID "0000-0002-5776-0540"

Grundy, Lorena S.  ^[1];

• Search DOE PAGES for author "Grundy, Lorena S."
• Search DOE PAGES for ORCID "0000-0001-7706-2216"

Takacs, Christopher J. ^[2]; Cao, Chuntian  ^[3];

• Search DOE PAGES for author "Cao, Chuntian"
• Search DOE PAGES for ORCID "0000-0003-4753-7334"

Steinrück, Hans-Georg  ^[4];

• Search DOE PAGES for author "Steinrück, Hans-Georg"
• Search DOE PAGES for ORCID "0000-0001-6373-0877"

Fu, Sean ^[5]; Rivas Valadez, Michael A. ^[5]; Toney, Michael F.  ^[6];

• Search DOE PAGES for author "Toney, Michael F."
• Search DOE PAGES for ORCID "0000-0002-7513-1166"

Balsara, Nitash P.  ^[1]

• Search DOE PAGES for author "Balsara, Nitash P."
• Search DOE PAGES for ORCID "0000-0002-0106-5565"

---

+ Show Author Affiliations

1. Univ. of California, Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2. SLAC National Accelerator Lab., Menlo Park, CA (United States)
3. SLAC National Accelerator Lab., Menlo Park, CA (United States); Univ. of Colorado, Boulder, CO (United States)
4. SLAC National Accelerator Lab., Menlo Park, CA (United States); Univ. Paderborn (Germany)
5. Univ. of California, Berkeley, CA (United States)
6. Univ. of Colorado, Boulder, CO (United States)

Publication Date:

Fri Aug 27 00:00:00 EDT 2021

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Transportation Office. Vehicle Technologies Office

OSTI Identifier:

1843009

Grant/Contract Number:  

AC02-05CH11231; AC02-76SF00515; AC02-06CH11357

Resource Type:

Accepted Manuscript

Journal Name:

Macromolecules

Additional Journal Information:

Journal Volume: 54; Journal Issue: 17; Journal ID: ISSN 0024-9297

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

25 ENERGY STORAGE; salts; electrochemical cells; electrolytes; lithium; electrodes