Effects of Temperature on Internal Resistances of Lithium-Ion Batteries

The performance of a lithium-ion battery is significantly dependent on temperature conditions. At subzero temperatures, due to higher resistances, it shows lower capacity and power availability that may affect adversely applications of these batteries in vehicles particularly in cold climate environment. To investigate internal resistances, LiMnNiO and LiFePO4 batteries were tested at wide temperature ranges from 50 °C to −20 °C. Using impedance spectroscopy, major internal resistances such as cathode interfacial, anode interfacial and conductive, have been identified by using a simple equivalent circuit. Results showed that at subzero temperatures the anode interfacial resistance was almost twice than the cathode interfacial resistance. A simple model of the individual resistance increment as a function of temperature has also been presented at the end of the paper. In addition, dependency of cell impedance on state of charge (SOC) and temperature has also been analyzed from the test results.