Thermal Fault-Tolerance in Lithium-ion Battery Cells: A Barrier Function based Input-To-State Safety Framework

Ever increasing demand and use of Lithium-ion batteries has made it necessary to put extensive efforts in their safety. While a lot of research is focused on safer battery materials and mechanical designs, developing control-based safety strategies is also a key aspect to enable safety. Most of the existing battery control strategies focus on optimal charging performance, leaving a gap on thermal safety control techniques. Specifically, thermal management of battery cells under thermal faults remains significantly under-explored. In light of this, we propose a fault-tolerant control algorithm which can practically ensure safety of Li-ion batteries in presence of thermal anomalies. In this algorithm, we formulate a control law which guarantees both the thermal safety and stability of Li-ion batteries. Specifically, we combine lumped parameter thermal model and Ordinary Differential Equation (ODE)-based practical input-to-state safety technique to formulate the thermal control problem. Subsequently, we utilize control barrier function and linear stability criteria to design the controller gains. Finally, we present simulation case studies to validate the efficacy of the proposed control algorithm.