An investigation on electrical and thermal characteristics of cylindrical lithium-ion batteries at low temperatures

Lithium-ion batteries suffer severe performance degradation and exhibit highly nonlinear characteristics under low-temperature environments. Determining the electrical and thermal characteristics is of significant in battery thermal management optimization and electrochemical energy utilization. In this study, the effects of various ambient temperatures and different discharge currents on electro-thermal behaviors are experimentally investigated, and various parameters, as functions of the depth of discharge, are comprehensively analyzed. The results indicate that decreasing the lithium-ion activity and the amount of useable active material and increasing the resistance lead to performance deterioration at low temperatures. The ohmic resistance shows slight deviations in the middle stage of discharge, and the polarization resistance gradually increases and provides the largest contribution to the total resistance as the battery discharge progresses. The irreversible heat generation caused by the internal resistance can be regarded as the sole heat source, to simplify the battery thermal model in certain cases. However, as the temperature increases and discharge current decreases, the reversible heat increases and can no longer be ignored. Finally, a lumped-parameter method is employed to derive the battery temperature. The calculated temperature variation agrees well with the experimental results, thus proving the effectiveness of the measurement.