The impact of multi-layered porosity distribution on the performance of a lithium ion battery

• Coupled electrochemical–thermal model in 3D. • Impact of a multi-layered porosity distribution within the positive electrode. • Reduction in the heat generation by multi-layered porosity. • Improved specific energy and power of the cell. • Correlation of the location of the hot spot with the electrode design. This study investigates the impact of a multi-layered porosity profile on the electrical and thermal performance of a lithium-ion battery. Consideration is given to key attributes of the battery, namely its specific power and energy and the temperature distribution that may generated throughout the cell under electrical load. The COMSOl Multiphysics software tool has been employed to develop a 3D electrochemical–thermal model of a commercially available 10 Ah lithium iron phosphate cell. Through an extensive simulation study, for a fixed value of active material, the impact of varying the porosity profile across both the thickness and height of the electrode has been studied. For each case study, the distribution of reaction current and the corresponding localised state of charge and temperature profile are quantified for a constant current discharge of 5C. Simulation results highlight that a multi-layered porosity distribution across the thickness of the electrode has the potential to yield superior battery performance compared to when the porosity is varied along the electrode height. Moreover, the total heat generation within the cathode may be reduced by up to 14% compared to a Reference Case, along with 0.33% and 0.44% improvement in the specific energy and power, respectively.