Effect of fluoroethylene carbonate as an electrolyte solvent in the LiNi0.5Mn1.5O4/Li4Ti5O12 cell

Abstract

Fluoroethylene carbonate (FEC) is used as solvent for the antioxidation electrolyte system in the LiNi0.5Mn1.5O4/Li4Ti5O12 cell. We use scanning electron microscopy to analyze the solid electrolyte interphase (SEI) film covered from the surface of individual particles to the top of electrodes. The stable, uniform SEI films formed on individual Li4Ti5O12 particles with FEC solvent are responsible for the significantly improved electrochemical performance. Meanwhile, our results show that severe swelling could be observed and heavier manganese (Mn2+) deposition could be detected on top of the Li4Ti5O12 electrode surface. In this study, we adopt the metathesis reaction to illustrate the relationship between gradual changes in the SEI film and swelling problems during cycling performance. Moreover, the reduction mechanisms of FEC proposed in this study have provided a better understanding of the key issue on electrolyte system that for commercial LiNi0.5Mn1.5O4/Li4Ti5O12 cell.