Crystal structure and cation-anion interactions of potassium (Difluoromethanesulfonyl) (trifluorome thanesulfonyl)imide

• Published in: Frontiers in chemistry Vol. 11; p. 1191394
• Main Authors: Sánchez-Diez, Eduardo, Garcia, Lorena, Arcelus, Oier, Qiao, Lixin, San Felices, Leire, Carrasco, Javier, Armand, Michel, Martínez-Ibañez, Maria, Zhang, Heng
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 12.07.2023
• Subjects: (Difluoromethanesulfonyl)(trifluoromethyanesulfonyl)imide; Cation-anion interaction; Chemistry; Crystal structure; Dihedral angle; Hydrogen-containing sulfonimide anion; Dihedral angle; (Difluoromethanesulfonyl)(trifluoromethyanesulfonyl)imide; Hydrogen-containing sulfonimide anion; Cation-anion interaction; Crystal structure
• ISSN: 2296-2646; 2296-2646
• DOI: 10.3389/fchem.2023.1191394

Sulfonimide salts are of great interest for battery use thanks to their special properties including sufficient superior chemical/thermal stabilities, structural flexibility, etc. In particular, the hydrogen-containing sulfonimide (difluoromethanesulfonyl)(trifluoromethanesulfonyl)imide anion {[N(SO 2 CF 2 H) (SO 2 CF 3 )] − , DFTFSI − }, stands out owing to its suppressed anion mobility and superior electrochemical properties. We herein report the structural analyses of potassium (difluoromethanesulfonyl)(trifluoromethanesulfonyl)imide {K [N(SO 2 CF 2 H) (SO 2 CF 3 )], KDFTFSI} by virtue of single crystal X-ray diffraction and computational approaches. Our results reveal that KDFTFSI crystallizes in a orthorhombic cell (space group: Pbcn) comprising of cationic and anionic layers, which is similar to the conventional sulfonimide salt, potassium bis(trifluoromethanesulfonyl)imide {K [N(SO 2 CF 3 ) 2 ], KTFSI}. Gas-phase density functional theory calculations show that the conversion from trans to cis DFTFSI − anions is hindered due to the presence of stabilizing intramolecular H-bonding interactions in the trans conformer; yet interaction with K + substantially minimizes the energy difference between the two conformers due to the formation of strong tridentate K + coordination with oxygen atoms in the cis KDFTFSI. This work is anticipated to provide further understanding on the structure-property relations of hydrogenated sulfonimide anions, and thus inspire the structural design of new anions for battery research.