Vinyl tris-2-methoxyethoxy silane – A new class of film-forming electrolyte components for Li-ion cells with graphite anodes

New type of electrolyte composition for Li-ion cells is described. The electrolyte includes propylene carbonate as the main solvent and is compatible with graphite anodes. The detrimental effect of propylene carbonate on the graphite structure is compensated by addition of vinyl tris-2-methoxyethoxy silane, a compound belonging to a particular class of silanes referred to as silicon podands, playing the role of film-forming component. It was proved within this work that electrolyte composed of 1 M LiPF6 in a solvent being a mixture of PC and vinyl tris-2-methoxyethoxy silane (10% by weight) can be suitable for Li-ion cells with graphitic anodes. Electrochemical tests revealed clearly a proper formation of passive layer on the graphite electrode during first charging and effective lithium ion intercalation/deintercalation. Mechanisms of solid electrolyte interface formation are discussed.