Study on Near‐Adiabatic Performance of Electric Vehicles' Lithium Battery at Low Temperature

Abstract

In recent years, electric vehicles have developed rapidly. However, as the power source of electric vehicles, lithium battery has poor performance at low temperature, and has some problems such as reduced capacity and increased internal resistance. In this paper, two thermal environments, including natural convection condition and near‐adiabatic condition, are established, and discharge capacity test and cyclic dynamic stress test (DST) are conducted for lithium iron phosphate batteries. The actual effect of near‐adiabatic conditions is analyzed from three perspectives: battery surface temperature, terminal voltage and EIS. The results show that the near‐adiabatic working condition has almost no effect on the discharge capacity at the standard discharge current (0.5 °C) under the same temperature conditions, ranging from −15 to 25 °C. In the low‐temperature − 10 and − 15 °C cyclic dynamic stress test, compared with the natural convection working condition, the near‐adiabatic condition has a rapid rise in terminal voltage one cycle earlier, causing the cycle to stop. Also, the polarization impedance increases at least twice after the cycle under the near‐adiabatic condition. Finally, according to the analysis of variance (ANOVA), the near‐adiabatic condition has a significant effect on voltage and polarization resistance at low temperatures. Still, it has almost no effect on ohmic resistance and discharge capacity. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.