Modeling the Effect of Over-discharge Cycling on Li-ion Batteries

Off-nominal circumstances inducing cell over-discharge in a battery, are of concern due to electrolyte decomposition and prolonged degradation effects. Copper dissolution and its subsequent deposition could lead to high cell temperatures and in some cases catastrophic failures during battery operational lifetime. Extending physics-based lithium-ion battery models for the purpose of simulating over-discharge conditions requires key considerations in model parameters, constitutive equations, and the SoC window of operation This paper reports a reduced-order model for over-discharge and simulating its effect under various scenarios using a Thermal Tanks-in-Series (TTiS) approach. The model was used to compare voltage-time behavior and capacity fade during cycling for different over-discharge cycling protocols. The efficacy of cycling simulations was validated with experimental data and the TTiS model demonstrates reasonable agreement with the voltage, temperature, and capacity fade trends under the given experimental cycling regimes.