Fluorinated Covalent Organic Polymers for High Performance Sulfur Cathodes in Lithium-Sulfur Batteries

Hyuksoo Shin, Doyun Kim, Hyeon Jin Kim, Jiheon Kim, Kookheon Char, Cafer T. Yavuz, Jang Wook Choi

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Lithium-sulfur (Li-S) batteries by far offer higher theoretical energy density than that of the commercial lithium-ion battery counterparts, but suffer predominantly from an irreversible shuttling process involving lithium polysulfides. Here, we report a fluorinated covalent organic polymer (F-COP) as a template for high performance sulfur cathodes in Li-S batteries. The fluorination allowed facile covalent attachment of sulfur to a porous polymer framework via nucleophilic aromatic substitution reaction (SNAr), leading to high sulfur content, e.g., over 70 wt %. The F-COP framework was microporous with 72% of pores within three well-defined pore sizes, viz. 0.58, 1.19, and 1.68 nm, which effectively suppressed polysulfide dissolution via steric and electrostatic hindrance. As a result of the structural features of the F-COP, the resulting sulfur electrode exhibited high electrochemical performance of 1287.7 mAh g-1 at 0.05C, 96.4% initial Columbic efficiency, 70.3% capacity retention after 1000 cycles at 0.5C, and robust operation for a sulfur loading of up to 4.1 mgsulfur cm-2. Our findings suggest the F-COP family with the adaptability of SNAr chemistry and well-defined microporous structures as useful frameworks for highly sustainable sulfur electrodes in Li-S batteries.
Original languageEnglish (US)
Pages (from-to)7910-7921
Number of pages12
JournalChemistry of Materials
Volume31
Issue number19
DOIs
StatePublished - Oct 8 2019
Externally publishedYes

ASJC Scopus subject areas

  • Materials Chemistry
  • Chemical Engineering(all)
  • Chemistry(all)

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