Post-Damage Short Circuit Detection in Lithium-ion Batteries

The rapid proliferation of electric vehicles underscores the pressing need to ensure the ongoing safety of their battery packs in the event of accidents or physical damage. Damaged Li-ion batteries are particularly susceptible to internal short circuits (ISC), which, if left undetected, can lead to catastrophic thermal runaway events. Thus, this research aims to develop a novel method for detecting incipient post-damage shorts where the cells cannot be further loaded and real-time voltage measurements are the only available data for analysis. We propose a non-linear Lyapunov-based observer to estimate the short circuit current to detect and quantify the extent of short circuits. Extensive simulations with different short circuit severity are performed to evaluate the effectiveness of the proposed approach in the presence of model uncertainties and measurement noise. The proposed approach is validated on external short circuit (ESC) experiments on two cells with different capacities and different chemistries. An ESC generating less than C/400 leakage current (caused by 15Ω short) is detected and quantified with 5% accuracy within 2.5 hours of its onset in a 111 Ah Li-ion NMC battery cell. In the 1.31Ah lithium polymer cell, an experimental ESC of 248Ω (or < C/81 leakage current) is quickly detected and quantified with 9.7% accuracy.