Effects and Attenuation Mechanism Analysis of a Fluoroethylene Carbonate Additive on SiOx/Graphite Anode-Based Pouch Cells

Although SiOx/graphite (SiOx/Gr) composite anodes are commercially applied to a certain extent, there are still some unsolved challenges, such as a large volume expansion during the lithiation/delithiation process, rapid performance attenuation at a high temperature, etc. In this work, we systematically discuss the effect of a fluoroethylene carbonate (FEC) additive on the SiOx/Gr anode-based pouch cells and make an in-depth attenuation mechanism analysis at a high temperature. Experimental results show that FEC can accelerate the generation of gas and HF after 60 °C storage, which will cause cathodic corrosion. Moreover, the loss of active Li and the failure of the electrode structure are two main factors resulting in performance degradation of SiOx/Gr||NCM811 pouch cells at a high temperature.