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Interfacial properties between ionic‐liquid‐based electrolytes and lithium‐ion‐battery separator
Author(s) -
Sun Yanjun,
Wang Jian,
Prausnitz John M.
Publication year - 2021
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.17208
Subject(s) - wetting , separator (oil production) , contact angle , electrolyte , ionic liquid , solvent , surface tension , electrochemistry , chemistry , lithium (medication) , chemical engineering , surface energy , materials science , inorganic chemistry , analytical chemistry (journal) , organic chemistry , composite material , thermodynamics , electrode , catalysis , medicine , physics , engineering , endocrinology
For lithium salts, ionic liquids (ILs) are promising alternatives to conventional solvents in lithium‐ion batteries (LIBs) due to a more favorable high‐voltage operating window, and due to improved safety through reduction of flammability. Toward better understanding of wetting properties of IL‐based electrolytes on a LIB separator, wetting properties affect electrochemical performance, experimental studies were made to determine the influence of solvent, lithium‐salt type and salt concentration. Surface tensions and advancing contact angles were measured for two pure ILs ([C 4 C 1 im][BF 4 ] and [C 4 C 1 im][OTf]) and for four IL/alkylcarbonate solvent blends (1:1 mass ratio, [C 4 C 1 im][BF 4 ]/PC, [C 4 C 1 im][BF 4 ]/DMC, [C 4 C 1 im][OTf]/PC, and [C 4 C 1 im][OTf]/ DMC) with several concentrations of a lithium salt (LiClO 4 , LiPF 6 , and LiTFSI). A significant improvement of wettability of pure ILs was observed by adding DMC, while adding PC with surface tension higher than that of pure ILs is detrimental to wetting behavior. Contact angles decrease by adding LiTFSI but show almost no change upon addition of LiPF 6 or LiClO 4 . Surface tensions follow the same trend as that for contact angles. Incorporation of TFSI − anion gives favorable separator wettability. Estimates were made for interfacial properties of the separator (dispersive and polar components of the surface free energy for solid‐vapor, for liquid–vapor, and for solid–liquid interfacial free energy).