Nitrile functionalized disiloxanes with dissolved LiTFSI as lithium ion electrolytes with high thermal and electrochemical stability

作者：Pohl Benjamin; Hiller Martin M; Seidel Sarah M; Gruenebaum Mariano; Wiemhoefer Hans Dieter

来源：Journal of Power Sources, 2015, 274: 629-635.

DOI：10.1016/j.jpowsour.2014.10.080

• Disiloxanes
• Dinitrile
• Aluminum corrosion inhibition
• Electrolyte stability
• Lithium ion battery

Liquid disiloxanes functionalized with terminal nitrile groups are introduced as alternative non-volatile solvents for lithium-ion battery electrolytes in combination with LiTFSI as lithium salt. Two series of disiloxanes were investigated differing with respect to the attachment of the nitrile containing side group to silicon, i.e. via a Si-C or a Si-O bond. Total conductivities up to 1 mS cm(-1) at 30 degrees C were measured by impedance spectroscopy. Electrochemical characterization was done on half cells using LiFePO4 cathodes by cyclic voltammetry and constant current cycling. Attractive issues and advantages of the investigated LiTFSI containing disiloxanes in comparison to current electrolyte solvents are: a) In spite of the presence of LiTFSI, the aluminum pitting corrosion is suppressed, b) the electrochemical stability window is extended on the cathode side up to 5.6 V vs. Li/Li+, for a LiTFSI concentration of 0.7 mol kg(-1), c) the reported nitrite functionalized disiloxanes show excellent thermal stability with a boiling point up to 106 degrees C (0.1 mbar), a rather low glass transition temperature of -107 degrees C, while no melting/crystallization was observed.

• 出版日期2015-1-15