A comprehensive methodology for characterization and electro-thermal modelling for a next-generation solid-state battery

Solid-state batteries (SSBs) offer higher energy densities, improved safety from non-flammable solid electrolytes, and longer lifespans compared to traditional lithium-ion batteries. However, modeling SSBs presents unique challenges due to their distinct electrical and thermal behaviors. This study presents an experimental characterization and electro-thermal model for a next-generation 30 Ah polymer-based SSBs. This work integrates experimental characterization, electrical modeling using a third-order equivalent circuit, and thermal modeling with a lumped thermal mass to represent temperature dynamics. Through comprehensive testing, including open-circuit voltage and hybrid pulse power characterization, we identified dependencies of key parameters on state of charge and temperature. Two-way coupling is used between the electrical and thermal models, where the first feeds the second one with the heat generated while the thermal model provides the temperature to update electrical parameters accordingly. This approach accounts for both irreversible heat from internal resistance and reversible heat from entropy changes, determined through a validated method correlating open-circuit voltage and temperature. Results demonstrate that the proposed model can simulate the dynamic interactions between the electric and thermal behavior of a SSB and predicts the electric performance as well as the cell surface temperature with high accuracy.