Simple experimental method to determine the specific heat capacity of cylindrical Lithium-Ion-Battery cells

Abstract

This study presents a new method for determining the specific heat capacity of cylindrical Lithium-Ion-Battery (LIB) cells. In comparison to other available methods, the developed procedure is simple, cost-efficient, non-destructive and reliable. The experimental setup only requires a standard LIB power characterization setup and one additional heat flux sensor (HFS). The HFS is wrapped around the studied sample and the sample is suspended in the middle of a climate chamber. The specific heat capacity can be determined by increasing the climate chamber temperature by ΔT=5K while continually measuring the temperature and heat flux. The method has been validated with an Al7075 cylindrical sample, showing deviations in the specific heat capacity compared to the results with a differential scanning calorimeter (DSC) of 0.35%. Further validation of the developed method has been achieved for a nickel manganese cobalt (NMC) cell, having a mean error of −0.37% compared to the mass-weighted-average method. Additionally, the method has been used to determine the specific heat capacity of a nickel cobalt aluminum (NCA) and lithium iron phosphate (LFP) LIB cell. While the dependency of the specific heat capacity on the State of Charge (SOC) seems to be neglectable (maximum deviation 2.29% in a LFP-cell), the temperature dependency (maximum 0.23%K−1 for NCA/NMC-cell) should be considered for the thermal modeling of LIBs.