Electrical Constriction Resistance in Current Collectors of Large-Scale Lithium-Ion Batteries

A new two-dimensional model is proposed to describe the electrical conduction in current collectors of prismatic lithium-ion batteries, and to investigate the effects of tab design on voltage drop. Polarization expression for a large-scale lithium-ion cell is determined experimentally and implemented in a numerical analysis to show that reaction current remains approximately uniform when depth-of-discharge is less than 85%. Based on this observation, a compact analytical model is developed to determine bulk and constriction/spreading resistances in current collectors. Moreover, the model predictions are successfully validated through comparisons with experimental data. It is demonstrated that constriction/spreading resistance in current collectors of the considered battery is fairly small; about 10% of the total cell resistance but it is larger than the contribution of bulk resistance which is about 3%. The model confirms that constriction/spreading increase with: decrease in the aspect ratio of the current collector, decrease in the tab width, and increase in the tab eccentricity.