Surface film formation on TiSnSb electrodes: Impact of electrolyte additives

Abstract

X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS) have been performed to study the formation of surface film on TiSnSb, a promising conversion anode material for lithium ion battery. TiSnSb electrodes were cycled using a standard EC/PC/3DMC (1 M LiPF6) electrolyte containing vinylene carbonate (VC) as a primary filming agent. Fluoroethylene carbonate (FEC) was added as an additional additive intended to improve the stability of the surface film and, hence, the cyclability of the electrode. Surface analysis was performed by a combined XPS core peaks and quantification data analysis to establish the main components of the solid electrolyte interphase film (SEI) were identified. The key observation is that the thickness and the chemical nature of the SEI layer is strongly related to the nature of the electrolyte additives. From XPS and EIS results, the role of FEC as an effective SEI improver in alkylcarbonate based electrolyte has been enlighten.