Axial and radial thermal conductivity measurement of 18,650 Lithium-ion battery

Abstract

Thermal conductivities of lithium-ion batteries are critical for the thermal management of battery packs. In this work, a novel method and experimental apparatuses are developed to measure the axial and radial thermal conductivities of the 18,650 LiNiCoAlO2 (NCA) lithium-ion battery. For the axial conductivity measurement, the one-dimensional steady conduction principle considering uniform heat loss is used, while the combined method of experiment and computational fluid dynamics (CFD) simulation is used for the radial conductivity measurement. By measuring the conductivity of the stainless steel cylinder, the errors are estimated to be less than 1.45 % and 1.37 % for the axial and radial measurement methods respectively. The axial and radial conductivities of the battery are measured at different open circuit voltage (OCV) and temperatures. Under the experimental conditions, the axial conductivity of the battery ranges from 10.26 to 14.20 W/m/K, and the axial conductivity generally increases with OCV and temperature. The radial conductivity ranges from 2.14 to 2.87 W/m/K if the battery core and the steel shell are considered as a whole; and the radial conductivity of the core ranges from 1.84 to 2.55 W/m/K if the core and the shell are considered separately. In the normal OCV range, there is no obvious relationship among the radial conductivity, temperature and OCV, whether the core and the shell are treated separately or not. This work may contribute towards improved thermal simulation of Li-ion cells.