Interfacial Study of the Role of SiO2 on Si Anodes Using Electrochemical Quartz Crystal Microbalance

One of the challenges associated with silicon as an anode material for Li-ion batteries is the

formation of an unstable solid-electrolyte interphase which, forms continuously while consuming

lithium and other components; and consequently contributes to irreversible capacity. To elucidate

some of the details of the formation and subsequent dissolution of species that form during lithiation of

silicon anodes we have produced thin film silicon electrodes with and without an oxide layer and

analyzed these during lithiation and delithiation using an electrochemical quartz microbalance with in-

situ dissipation (EQCM-D). Measurements were conducted both in EC:EMC and EC:DEC:FEC based

electrolytes. Mass loss during lithiation was observed in both solvents systems when an oxide layer

was present on the electrode and this was found to be associated with Li2O dissolution using solution

and solid state NMR.