Study Of Temperature Difference And Current Distribution In Parallel-Connected Cells At Low Temperature

Abstract

Two types of commercial cylindrical lithium ion<br> batteries (Panasonic 3.4 Ah NCR-18650B and Samsung 2.9 Ah<br> INR-18650), were investigated experimentally. The capacities of these<br> samples were individually measured using constant current-constant<br> voltage (CC-CV) method at different ambient temperatures (-10°C,<br> 0°C, 25°C). Their internal resistance was determined by<br> electrochemical impedance spectroscopy (EIS) and pulse discharge<br> methods. The cells with different configurations of parallel connection<br> NCR-NCR, INR-INR and NCR-INR were charged/discharged at the<br> aforementioned ambient temperatures. The results showed that the<br> difference of internal resistance between cells much more evident at<br> low temperatures. Furthermore, the parallel connection of NCR-NCR<br> exhibits the most uniform temperature distribution in cells at -10°C,<br> this feature is quite favorable for the safety of the battery pack.