Utilizing the Elimination Reaction of Linear Fluorinated Carbonate to Stabilize LiCoO2 Cathode up to 4.6 V

Abstract

Stabilizing LiCoO₂ (LCO) cathode at high voltages is still challenging in lithium-ion batteries (LIBs). Although fluorinated solvents are utilized in high-voltage systems for their superior oxidation resistance, linear fluorinated carbonates still undergo elimination reactions at high voltages, producing corrosive substances that compromise electrode materials. This study addresses the elimination reaction of methyl trifluoroethyl carbonate (FEMC) by incorporating tris(trimethylsilyl)-based additives, thereby constructing a homogeneous and robust polymer-rich cathode-electrolyte interphase (CEI). With the incorporation of tris(trimethylsilyl)phosphite in the optimized electrolyte, the capacity of the coin cell with LCO as the cathode can maintain 95% after 500 cycles with a high cut-off voltage of 4.6 V. This study establishes a foundational framework for employing linear fluorocarbonates in high-voltage systems and provides innovative insights into CEI design and construction.