AUTHOR=Sánchez-Diez Eduardo , Garcia Lorena , Arcelus Oier , Qiao Lixin , San Felices Leire , Carrasco Javier , Armand Michel , Martínez-Ibañez Maria , Zhang Heng 

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

JOURNAL=Frontiers in Chemistry

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2023.1191394

DOI=10.3389/fchem.2023.1191394

ISSN=2296-2646

ABSTRACT=<p>Sulfonimide salts are of great interest for battery use thanks to their special properties including sufficient superior chemical/thermal stabilities, structural flexibility, <italic>etc.</italic> In particular, the hydrogen-containing sulfonimide (difluoromethanesulfonyl)(trifluoromethanesulfonyl)imide anion {[N(SO<sub>2</sub>CF<sub>2</sub>H) (SO<sub>2</sub>CF<sub>3</sub>)]<sup>−</sup>, DFTFSI<sup>−</sup>}, 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<sub>2</sub>CF<sub>2</sub>H) (SO<sub>2</sub>CF<sub>3</sub>)], 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<sub>2</sub>CF<sub>3</sub>)<sub>2</sub>], KTFSI}. Gas-phase density functional theory calculations show that the conversion from <italic>trans</italic> to <italic>cis</italic> DFTFSI<sup>−</sup> anions is hindered due to the presence of stabilizing intramolecular H-bonding interactions in the <italic>trans</italic> conformer; yet interaction with K<sup>+</sup> substantially minimizes the energy difference between the two conformers due to the formation of strong tridentate K<sup>+</sup> coordination with oxygen atoms in the <italic>cis</italic> 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.</p>