On the warmup of Li-ion cells from sub-zero temperatures

Lithium (Li) ion cells suffer from significant performance degradation at sub-zero temperatures. This paper presents a Predictive Control based technique that exploits the increased internal resistance of Li-ion cells to improve the power capability of Li-ion cells operating at sub-zero temperatures. The current is shaped as bi-directional pulses to minimize total energy discharge and adverse side reactions. The magnitude of current is determined by solving an optimization problem that penalizes energy loss. The penalty in energy loss is found to be influence the size external storage elements. When compared with the case when no penalty is imposed, gains of up to 20% are noted through simulations.