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 ([C₄C₁im][BF₄] and [C₄C₁im][OTf]) and for four IL/alkylcarbonate solvent blends (1:1 mass ratio, [C₄C₁im][BF₄]/PC, [C₄C₁im][BF₄]/DMC, [C₄C₁im][OTf]/PC, and [C₄C₁im][OTf]/ DMC) with several concentrations of a lithium salt (LiClO₄, LiPF₆, 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 LiPF₆ or LiClO₄. 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).

中文翻译：

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离子液体基电解质与锂离子电池隔板之间的界面性质

对于锂盐，离子液体（ILs）是锂离子电池（LIB）中常规溶剂的有前途的替代品，这是因为它具有更好的高压操作范围，并且通过降低可燃性提高了安全性。为了更好地理解LIB隔膜上IL基电解质的润湿性能，润湿性能会影响电化学性能，进行了实验研究以确定溶剂，锂盐类型和盐浓度的影响。测量了两种纯净离子液体（[C ₄ C ₁ im] [BF ₄ ]和[C ₄ C ₁ im] [OTf]）和四种IL /碳酸烷基酯溶剂共混物（1：1质量比）的表面张力和前进接触角，[C ₄ C₁ im] [BF ₄ ] / PC，[C ₄ C ₁ im] [BF ₄ ] / DMC，[C ₄ C ₁ im] [OTf] / PC和[C ₄ C ₁ im] [OTf] / DMC ）和几种浓度的锂盐（LiClO ₄，LiPF ₆和LiTFSI）。通过添加DMC可以观察到纯IL的润湿性有显着改善，而添加表面张力高于纯IL的PC则对润湿性能有害。通过添加LiTFSI，接触角减小，但是在添加LiPF ₆或LiClO ₄时，接触角几乎没有变化。表面张力遵循与接触角相同的趋势。合并TFSI⁻阴离子赋予良好的隔板润湿性。对分离器的界面特性进行了估算（固体蒸气，液体蒸气和固体-液体界面自由能的表面自由能的分散和极性成分）。