Understanding the Role of Fluoroethylene Carbonate As a Electrolyte Additive in Silicon Anode Lithium-Ion Batteries

Abstract

Silicon is regarded as one of the most promising anode material for lithium ion batteries (LIBs). It has a high theoretical capacity of 3579 mAh/g. In order to make silicon commercially viable, the two key challenges need to be addressed: high volume expansion during lithiation/delithiation process and formation of unstable solid electrolyte interphase (SEI) at the silicon-electrolyte interface. Specially, to address the unstable SEI formation, different types of strategies are adopted such as; use of carbon coated silicon surface, use of nano-silicon materials, modification of the binder and use of additive in the electrolyte. Previous studies have reported1,2 that the fluoroethylene carbonate (FEC) additive improves the performance of the silicon anode. Although research efforts are focused on understanding the cause of improvement in the performance of LIBs with FEC electrolyte additive, the underlying mechanism mostly remains unclear. In this work, we studied the effect of FEC additive on the performance silicon anode in half as well as the full-cell configuration of LIBs comprising NMC cathode and attempted to find the underlying mechanism. To complement the experimental results, we provide key insights from the first principle to uncover the role of FEC additive in silicon anode LIBs.