Experimental analysis and transient thermal modelling of a high capacity prismatic lithium-ion battery

In this paper, a three-dimensional transient model, predicting the thermal behaviour of a 60 Ah prismatic Li-ion battery during charge/discharge cycles under natural convection, is proposed. Also, an experimental test bench is used to charge and discharge the battery at different current rates (1C, 5/6C and 2/3C) in order to track its thermal behaviour using thermocouples and heat flux sensors. The model includes heat generation and solves conduction inside the battery and natural convection as boundary condition. Some of the required parameters, such as heat transfer coefficients, thermal conductivities along y and z directions and electrical resistance, are determined using experimental data. Heat capacity, thermal conductivity along x direction and entropy change are determined based on literature. Simulated battery surface temperatures are compared to experimental measurements resulting in less than 5% relative error. Additionally, core temperatures as well as reversible and irreversible heat generations are simulated using the proposed model. Simulated total heat generation is compared to measured heat generation at steady state showing a good agreement, which makes it possible, using this simple model, to predict the maximum heat generated inside the battery, and consequently the core temperature, in order to design a suitable thermal management system.