Investigating effects of pulse charging on performance of Li-ion batteries at low temperature

Pulse charging is a technique that charges a battery using a current that periodically changes in direction, potentially reducing battery charging time while improving its charging performance. The objective of this paper is to study how the pulse charging method improves charging time and battery performance at the low ambient temperature using both experimental testing and numerical simulation. A capacity protection ratio, defined as the ratio of the remaining charging capacity to the total charging capacity, is used to characterize pulse charging to prevent over-discharging. The capacity protection ratio shows more effect on the total charging time. An electrochemical and thermal coupled model is developed to explore the working principle of the pulse charging method. The experimental results show that the pulse charging method with 12C pulse discharge rate and 25% capacity protection ratio can reduce the charging time by 11% at −8.5 °C compared to the traditional constant current (1C) and constant voltage charging method. The model results show that pulse charging enhances uniformity of lithium-ion distribution in the battery, thereby improving the battery performance. This research demonstrates pulse charging is a viable option to improve battery charging performance at low temperatures compared to the CC-CV charging method.