A Simplified Thermal Model to Predict Temperature Profile and Heat Generation of Cylindrical Lithium-Ion Cells

Abstract

AbstractThe cylindrical lithium-ion cells are being considered as one of the preferred energy storage systems in Electric Vehicles (EV). However, they have operational challenges involving temperature that greatly affects its life and performance. If the cell operating temperature exceeds the threshold limit, decomposition of the battery active material may occur which can trigger thermal runaway leading to the explosion in certain conditions. Therefore, a battery thermal model is essential to analyze the thermal response of the cell to design an efficient and effective battery thermal management system. This paper presents a simplified unsteady one-dimensional radial analytical thermal model to predict the temperature profile and heat generation of an isolated cylindrical cell under natural and forced convection. The model treats the cell as homogeneous body with uniform heat generation throughout the cell and the thermo-physical properties of the cell are assumed to be independent of temperature. The prediction of the model on the effect of forced convection cooling on the surface temperature of the cell for different heat transfer coefficient values is quite interesting. It is seen that surface temperature is under 30 °C for heat transfer co-efficient of 100 W/m2 °C. The core and surface temperature non-uniformity across the radius of the cell is nearly 2 °C for different state of charge (SOC).KeywordsLithium-ionHeat generationBattery thermal model