Enhancement of High Voltage Cycling Performance of Lithium-ion Cells by Using Phosphazene-based Additive

Abstract

To improve the energy density of lithium-ion batteries (LIBs), high voltage operating is essential. However, there are several issues in the high voltage operation of LIBs, such as, structural deterioration of cathode material and oxidative decomposition of the electrolyte. Among several strategies to overcome these issues, applying functional additive is considered as one of the most efficient methods. A functional additive can form cathode electrolyte interphase (CEI) on the cathode surface, which suppresses the irreversible side reactions. In our study, we report phenoxy pentafluorocyclotriphosphazene (PPFPh) as a functional additive with different concentrations to form the stable CEI layer in the LiCoO2/graphite full cell. As a result, the cell employing electrolyte with 1 wt.% PPFPh exhibited improved capacity retention of 81% after 100 cycles.