Abstract
This paper presents an experimental study using an ultrasonic technique to investigate the impact of extremely low temperatures on the performance of lithium-ion batteries. Lithium-ion polymer batteries were aged in three low-temperature conditions: in a temperature chamber (-34 °C), in a dry ice bath (-78 °C), and in a liquid nitrogen bath (-196 °C). The battery aged in liquid nitrogen was damaged. The batteries aged in the chamber and dry ice bath were then subjected to charge and discharge cycles and simultaneously monitored using the ultrasonic technique. Three key ultrasonic parameters were measured, signal amplitude, time of flight (TOF), and TOF shift, using 5 MHz commercial ultrasonic transducers. These measurements were conducted alongside electrical measurements (voltage and current) to monitor the batteries throughout the testing cycles. The results showed that the aged batteries exhibited significantly lower ultrasonic amplitude compared to the control batteries. Additionally, as the cycle number increased, the TOF increased and the discharge capacity decreased. The TOF shift increased linearly with the discharge capacity. However, no clear correlation was observed between the slope of this linear relationship and the low-temperature aging history of the batteries. Overall, the ultrasonic amplitude proved to be a reliable parameter for differentiating the control and low-temperature aged batteries.