Impact of Polymer Interlayers on All-Solid-State Battery Performance Using a Physicochemical Modeling Approach

Abstract

Recent studies presented the advantages of incorporating solid-polymer-electrolyte (SPE) interlayers in all-solid-state batteries (ASSB). Still, drawbacks regarding the cell performance are expected due to additional polymer-related overpotentials. The pseudo-two-dimensional (p2D) physicochemical model is extended to account for Li-ion transport in the SPE interlayer and in the ceramic LLZO solid electrolyte (SE), as well as for the charge transfer at the SPE∣LLZO interface using Butler-Volmer-like kinetics. The overpotential analysis for a reference parameterization disclosed a dominant overpotential contribution from the SPE∣LLZO charge transfer and a facilitation with increasing discharge C-rate. Variance-based global sensitivity analyses demonstrate that as the exchange current density between SPE and LLZO increases, polarization losses exhibit an exponential-like reduction. Additionally, the radius of the active material (AM) particles within the composite cathode exerts a significant and dominant influence on cell performance. With an optimization of the SPE∣LLZO exchange current density, the accessible capacity could be increased compared to the reference parameterization from 41% to 61% for a 2C discharge.