Safe Discharging of a Lithium-Ion Battery Using Observer-Based Control Lyapunov Function and Barrier Function via Quadratic Programming

Safety concerns associated with lithium-ion batteries (LiBs) have become increasingly prominent due to their widespread use in electronic devices. Physical or electrical damage can lead to short circuits (SC), potentially triggering thermal runaway (TR) if not properly managed. TR is particularly hazardous at high states of charge (SoC) due to the presence of residual energy. This research aims to develop a method for estimating unmeasurable states and safely discharging LiBs based on these estimates. A Lyapunov-based observer is proposed to estimate the SoC, SC current, and core temperature. To ensure safe discharge, an input-to-state exponentially stabilizing control Lyapunov function and a perturbation control barrier function are formulated and implemented via quadratic programming. These tools are used to design a controller that accounts for estimation errors while utilizing the estimated SoC and core temperature. The proposed approach is validated using a simulation model of a 111Ah cell. The observer yielded accurate state estimates, enabling a safe discharge from 100% to 50% SoC within 14 minutes while maintaining all safety constraints.