LAUSR

While silicon has long been targeted as a high energy-density anode material for lithium-ion batteries, uncontrolled electrolyte decomposition on its surface has caused poor cycle life and low columbic efficiencies compared to graphite anodes. A variety of additives have been shown to improve battery cycle performance by altering the chemical processes occurring at the electrode surfaces, but relatively little is known about the underlying mechanisms. In this work, we describe simultaneous application of in operando electrochemical quartz crystal microbalance (EQCM) and electrochemical impedance spectroscopy (EIS) measurements to understand the influence of a model organosilicon additive on silicon anodes during first-cycle charge and discharge. X-ray photoelectron spectroscopy (XPS) was also used to investigate the differences in composition of solid electrolyte interface (SEI) layers formed in the presence and absence of the additive. EQCM-EIS experiments demonstrated an increase in cell impedance early in the cycle, which lead to the suppression of early electrolyte decomposition on the model anode surface. XPS revealed that OS-treated cells create thinner SEI layers that were richer in LiF and contained less organic material than cells without OS.