Insulating Characteristics and Ionic Conductivity Properties of the Solid Electrolyte Interface in Lithium-Ion Batteries to Improve a Redox-Mediated Enhanced Coulometry Method

The Solid Electrolyte Interface (SEI) in lithium-ion batteries plays a critical role in key performance indicators such as cycle life and the significance of its ionic conductivity and electrically-protecting character. The SEI layer’s chemical composition and structure significantly influence its ionic conductivity, and various strategies exist to enhance its electrically-protecting character while maintaining adequate ionic conductivity. Herein, a Redox-Mediated Enhanced Coulometry method is presented, which enables evaluation of both protecting character and ionic conductivity of the SEI, which allows estimation of cycle life at various temperatures. The method is based on the electrochemical impedance spectroscopy (EIS) technique and coulombic efficiency measurements in the presence of redox mediators. The impact of electrolyte additives at different temperatures has been used to demonstrate the potential of the proposed method.