Electrode Parameterization as an Investigative Tool for Solid Electrolyte Interphase Evolution Monitoring on Commercial Lithium-Ion Battery Electrodes

Abstract

The formation process is one of the most critical aspects of lithium-ion battery (LIB) production. It involves the creation of an interface layer known as solid electrolyte interphase (SEI). The layer predominantly forms during the first few charging cycles of the battery, resulting in approximately 10% capacity reduction [1]. However, forming a stable SEI layer is critical in ensuring uniform cell capacity, safe operation, and a long lifetime of LIBs [2].The thickening of the SEI layer is one of the main contributors to capacity fade over the battery lifetime and strongly depends on electrochemical cycling conditions [1]. Despite its importance, there are still no comprehensive theories and models describing SEI formation and evolution. The difficulties arising from its characterization could explain why various structure models have appeared in the literature [3–5]. Therefore, it is indispensable to go beyond traditional characterization methods to fully elucidate the SEI layer behaviours.In this work, we investigate changes in the kinetic and thermodynamic electrode parameters with growing SEI layer thickness, deriving relevant variables, such as exchange current density, electrode tortuosity, and lithium diffusion coefficient from experimental data. The measurements are performed on commercially relevant electrodes. Parameter evolution monitoring will contribute to developing a predictive understanding of the SEI layer evolution under different cycling conditions, and to unlocking improvements in LIB sustainability by prolonging their lifetime and enhancing safety.