Assessing the Impact of Electrode Structure on the Thermal Behaviour of 18650 Li-ion Batteries: A Physics Based Modelling Approach

Abstract

Thermal management is one of the significant concerns of the commercial cylindrical 18650 Li-ion battery, as it can affect battery performance, lifespan, and safety. In the present work, we develop and implement an experimentally validated pseudo-2D lithium-ion battery model electrochemical coupled with the thermal model to investigate the electrochemical and thermal behaviour of the commercial 18650 lithium iron phosphate battery made of LiFePO₄ cathode and graphite anode. We integrate a bio-inspired electrolyte channel design into electrodes to improve thermal performance, especially during high C-rate discharging. This proposed model is established and simulated by using COMSOL Multiphysics 6.2. Four cell geometries were analysed for this work: one conventional cell, channel in the positive electrode, channel in the negative electrode, and channel in both electrodes. We investigate the effects of electrolyte channel width, thickness, and channel number for designed geometries on electrochemical and thermal performance. The findings indicate that a specific set of channel geometrical parameters can significantly reduce battery temperature during discharging. The addition of an electrolyte channel into the negative electrode with 50 nm width, 5 µm thickness, and 5 number channels provides optimum thermal performance. It decreases temperature for 2C and 3C by 8.4% and 5.45%, respectively. This study provides an electrode design strategy to improve the thermal performance of commercial 18650 Li-ion batteries.