Critical Understanding of Temperature Gradient During Fast Charging of Lithium-ion Batteries at Low Temperatures
Chandan Chetri, Akash Samanta, Sheldon S. Williamson
Abstract
Fast charging of lithium-ion battery (LIB) packs at low temperatures can have several effects on the performance and overall health of the battery. Repetitive fast charging at low temperatures accelerates internal resistance growth, leading to inefficient charging. Slow and inefficient chemical reactions at low temperatures result in slower charging rates and increased heat generation. Furthermore, repeated fast charging at subzero temperatures accelerates degradation processes due to increased wear on the battery, significantly reducing the cycle life of the battery. This research paper presents a series of experimental studies conducted on a 21700 Lithium-Nickel-Manganese-Cobalt-Oxide (NMC) LIB cell to investigate the temperature gradient and its impact on battery performance at a wide range of ambient temperatures (-5°C to 25°C) and charging rate (1C to 2 C). The findings highlight the highest rate of change of surface temperature and differential temperature (15°C) with a charging rate of 2 C at ambient temperature of -5°C. Moreover, a reduction in battery discharge performance is observed during low-temperature charging compared to charging at 25°C with the same charging rate. These findings are crucial for the development of health-conscious fast charging algorithms, improved thermal management techniques, and the establishment of a thermal safety framework.