Title: Designing electrolytes with polymerlike glass-forming properties and fast ion transport at low temperatures

Abstract

In the presence of Lewis acid salts, the cyclic ether, dioxolane (DOL), is known to undergo ring-opening polymerization inside electrochemical cells to form solid-state polymer batteries with good interfacial charge-transport properties. Here we report that LiNO₃, which is unable to ring-open DOL, possesses a previously unknown ability to coordinate with and strain DOL molecules in bulk liquids, completely arresting their crystallization. The strained DOL electrolytes exhibit physical properties analogous to amorphous polymers, including a prominent glass transition, elevated moduli, and low activation entropy for ion transport, but manifest unusually high, liquidlike ionic conductivities (e.g., 1 mS/cm) at temperatures as low as -50 °C. Systematic electrochemical studies reveal that the electrolytes also promote reversible cycling of Li metal anodes with high Coulombic efficiency (CE) on both conventional planar substrates (1 mAh/cm² over 1,000 cycles with 99.1% CE; 3 mAh/cm² over 300 cycles with 99.2% CE) and unconventional, nonplanar/three-dimensional (3D) substrates (10 mAh/cm² over 100 cycles with 99.3% CE). Our finding that LiNO₃ promotes reversibility of Li metal electrodes in liquid DOL electrolytes by a physical mechanism provides a possible solution to a long-standing puzzle in the field about the versatility of LiNO₃ salt additives for enhancing reversibility of Li metal electrodesmore » in essentially any aprotic liquid electrolyte solvent. As a first step toward understanding practical benefits of these findings, we create functional Li||lithium iron phosphate (LFP) batteries in which LFP cathodes with high capacity (5 to 10 mAh/cm²) are paired with thin (50 μm) lithium metal anodes, and investigate their galvanostatic electrochemical cycling behaviors.« less

Authors:

Zhao, Qing  ^[1];

• Search DOE PAGES for author "Zhao, Qing"
• Search DOE PAGES for ORCID "0000-0003-0625-9892"

Liu, Xiaotun ^[1]; Zheng, Jingxu ^[2]; Deng, Yue ^[2]; Warren, Alexander  ^[1];

• Search DOE PAGES for author "Warren, Alexander"
• Search DOE PAGES for ORCID "0000-0001-9432-4919"

Zhang, Qiyuan ^[1]; Archer, Lynden  ^[3]

• Search DOE PAGES for author "Archer, Lynden"
• Search DOE PAGES for ORCID "0000-0001-9032-2772"

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+ Show Author Affiliations

1. Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853,
2. Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853
3. Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853,, Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853

Publication Date:

Mon Oct 05 00:00:00 EDT 2020

Research Org.:

Cornell Univ., Ithaca, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1670470

Alternate Identifier(s):

OSTI ID: 1852093

Grant/Contract Number:  

SC0016082

Resource Type:

Published Article

Journal Name:

Proceedings of the National Academy of Sciences of the United States of America

Additional Journal Information:

Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Volume: 117 Journal Issue: 42; Journal ID: ISSN 0027-8424

Publisher:

Proceedings of the National Academy of Sciences

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; 42 ENGINEERING; science & technology; electrolytes; ion transport; lithium batteries; thermal transition; coupled dynamics