Cobalt(II)‐Centered Fluorinated Phthalocyanine‐Sulfur SNAr Chemistry for Robust Lithium–Sulfur Batteries with Superior Conversion Kinetics. (17th September 2021)

• Record Type: Journal Article
• Authors: Kim, Jiheon; Shin, Hyuksoo; Yoo, Dong‐Joo; Kang, Sangho; Chung, Sung‐Yoon; Char, Kookheon; Choi, Jang Wook
• Is Part Of: Advanced functional materials. Volume 31:Number 51(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-09-17
• Subjects: lithium‐sulfur batteries -- nucleophilic aromatic substitution -- phthalocyanine -- polysulfides -- reduced graphene oxide; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202106679
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Due to the exceptional theoretical energy density and low cost of elemental sulfur, lithium–sulfur (Li–S) batteries are spotlighted as promising post‐lithium‐ion batteries. Despite these advantages, the performance of Li–S batteries would need to be improved further for their wide dissemination in practical applications. Here, cobalt(II)‐centered fluorinated phthalocyanine, namely, F‐Co(II)Pc, is reported as a multi‐functional component for sulfur cathodes with the following benefits: 1) enhanced conversion kinetics as a result of the catalytic effect of the cobalt(II) center, 2) efficient sulfur linkage via the fluorine functionality, which undergoes a nucleophilic aromatic substitution (SN Ar) reaction, 3) suppression of the shuttling issue by the nitrogen atoms because of their strong affinity with polysulfides, and 4) the necessary aromaticity to engage in π–π interaction with reduced graphene oxide for electrical conductivity. The resulting electrode has promising electrochemical properties, such as sustainable cycling for 700 cycles and robust operation with a sulfur loading of 12 mgsulfur cm −2, unveiling the promising nature of phthalocyanine and its related molecular families for advanced Li–S batteries. Abstract : Cobalt(II)‐centered fluorinated phthalocyanine (F‐Co(II)Pc) is introduced as a multi‐functional component for sulfur electrodes in Li–S batteries. F‐Co(II)Pc improves the kinetics of the conversion reaction by utilizing the catalytic effect of cobalt(II), enables covalent linkage with elemental sulfur, mitigates the shuttling effect, and engages in π–π interaction with reduced graphene oxide, with the combined effect of robust cycling with a sulfur loading of 12 mgsulfur cm −2 .