Enhanced graphite passivation in Li-ion battery electrolytes containing disiloxane-type additive/co-solvent

This article reports the synthesis details and film-forming properties of 1,1,3,3-tetramethyl-1,3-bis(3-(omega-hexadecyloxy-deca(ethylenoxy)propyl)disiloxane, a new potential electrolyte additive/functional co-solvent for propylene carbonate (PC)-based Li-ion cells with graphitic anodes. Galvanostatic charge/discharge characteristics and scanning electron microscopy images provide direct evidence for the suppression of solvent intercalation and graphite exfoliation in the presence of the additive. In terms of irreversible capacity, the additive's efficiency is the highest for 15% weight ratio in the solvent mixture. Potentiodynamic measurements have revealed that disiloxane component undergoes irreversible reduction at potential significantly higher then PC decomposition. Energy dispersive spectroscopy analysis of graphite flake surfaces confirm that silicon species from the disiloxane decomposition are built in the passive layer. The reported compound may be considered as a basis for alternative cost-effective electrolyte compositions for low-temperature applications.