Poro-mechanical analysis of a structural battery electrolyte: Experimental study and model calibration

We present the calibration and validation of a continuum poro-viscoelastic model for a structural battery electrolyte in the finite deformation setting. The model is based on a Maxwell type rheology incorporating a Norton evolution law, coupled with a simple Darcy type seepage formulation to describe fluid transport. Experiments were performed using in-house manufactured cylindrical specimens subjected to uniaxial compression at different strain rates. Radial deformation of the specimens was recorded using an optical camera, while mass measurements before and after compression were used to quantify liquid electrolyte seepage. The experimental data were used to calibrate the model. Furthermore, independent stress relaxation tests conducted at varying strain rates were used for validation. The proposed model successfully captures the rate-dependent stress–strain behaviour, radial extension, and associated mass loss due to seepage, particularly at large compressive strains. Some discrepancies remain in the representation of time dependent relaxation at higher strain rates. The framework provides a robust foundation for describing coupled solid–fluid interaction in structural battery electrolytes and supports future efforts toward micromechanical modelling and design optimization of multifunctional energy storing composites.