Analysis of Discharge Behaviour and Heat Generation at in the 18650 Lithium Ion Battery Cell

The rapid adoption of electric vehicles has heightened the demand for high-performance lithium-ion batteries (LiBs), where effective thermal management is critical to ensuring safety, reliability, and lifespan.This study aims to experimentally investigate the discharge behaviour and heat generation characteristics of a commercial Samsung 18650 LiB cell at varying discharge rates (DRs), and to develop a predictive model for heat generation.The cell was discharged at 1C, 2C, and 3C in constant current mode, while measuring voltage drop and surface temperature.Bernardi's model was employed to estimate the rate of heat generation (RHG).Results show that RHG increased with DR, recorded as 4.18 W, 8.05 W, and 11.37 W for 1C, 2C, and 3C, respectively.The corresponding surface temperature rises were 11.8C, 16.8C, and 20.2C, with temperature non-uniformities of 1.5C, 2.4C, and 3.7C.A polynomial-based mathematical model was developed using MATLAB to predict RHG with high accuracy, achieving RMSE values of 0.0315, 0.0708, and 0.1163, respectively.These findings establish a quantitative foundation for battery thermal behavior, providing essential data for the design and simulation of battery thermal management systems (BTMS).Future work may extend this modeling to different cell chemistries and integrate it with real-time BTMS strategies.Overall, this study contributes a reliable framework for thermal performance prediction in cylindrical LiB cells under dynamic discharge conditions.