27.8 Dynamic-Charging Current-Scaling Technique with Dual Accurate Current Control and Temperature Loops with Charging-Current Accuracy up to 99.6% for 1.6× Faster Lithium-Ion Battery Charging

Reliability is one of the most important issues for lithium-ion (Li-Ion) battery fast charging. Due to the limited charge-acceptance rate of a Li-Ion battery, a fast charging technology needs to consider the main problems that can result in LiIon battery damage [1]. Pumping large amounts of energy into a Li-Ion battery, faster than the battery chemicals can react to the charge, can result in local polarization of the electrode, overheating, and unpredictable chemical reactions that can damage the Li-Ion battery. Conventional battery chargers use over-temperature and under-temperature protection [2], while some advanced battery chargers contain a temperature-controlled current to limit the charging current for safe charging [3]. In the event of overheating, a fast charging mechanism should stop until the temperature drops to a safe level. Fast charging on/off control is not the single unique factor that determines charging time [4]. Similar to dynamic voltage and frequency scaling (DVFS) technology in power management ICs (PMICs), this paper proposes a dynamic charge current scaling (DCCS) technique, which dynamically adjusts the charging current and the termination charging voltage in constant-current (CC) charge mode depending on the battery temperature $( T_{mathrm{BAT}})$and the built-in resistance detection (BIRD) technique.