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Poly(ethylene Glycol-Block-2-Ethyl-2-Oxazoline) as Cathode Binder in Lithium-Sulfur Batteries

preprint
submitted on 18.05.2021, 15:04 and posted on 21.05.2021, 13:40 by Yu-Chuan Chien, Hohyoun Jang, Daniel Brandell, Matthew Lacey
Functional binders constitute a strategy to overcome several challenges that lithium–sulfur (Li–S) batteries are facing due to soluble reaction intermediates in the positive electrode. Poly(ethylene oxide) (PEO) and poly(vinylpyrrolidone) (PVP) are in this context a previously well-explored binder mixture. Their ether and amide groups possess affinity to the dissolved sulfur species, which enhances the sulfur utilization and mitigates the parasitic redox shuttle. However, the immiscibility of PEO and PVP is a concern for electrode stability. Copolymers comprising ether and amide groups are thus promising candidates to improve the stability the system. Here, a series of poly(ethylene glycol-block-2-ethyl-2-oxazoline) with various block lengths is synthesized and explored as binders in S/C composite electrodes in Li-S cells. While the electrochemical analyses show that although the sulfur utilization and capacity retention of the tested electrodes are similar, the integrity of the as-cast electrodes can play a key role for power capability.

History

Email Address of Submitting Author

yuchuan.chien@kemi.uu.se

Institution

Uppsala University

Country

Sweden

ORCID For Submitting Author

0000-0003-4767-9471

Declaration of Conflict of Interest

None