On the Implication of Porosity Configuration on Lithium-Ion Cell Performance: A Numerical Study

Abstract

The present study numerically investigates the implication of different porosity configurations, viz., uniform, algebraic, trigonometric, logarithmic, and stepwise constant porosities at the negative electrode on performance characteristics of Lithium-ion cell. We assess the merit of nonuniform porosity over uniform one in terms of cell performance characteristics, viz., specific energy, capacity, electrolyte salt concentration, local volumetric current density, power dissipation density, and solid lithium concentration. Our results reveal that specific energy and capacity are found to be maximum when the porosity increases logarithmically in the direction from the negative electrode–current collector to negative electrode–separator interface. Also, it is found that the variation of power dissipation density and electrolyte salt concentration characteristics are dictated by the interplay of the porosity and the length of the negative electrode. Furthermore, the effect of charging rates (quick charge, fast charge, and ultrafast charge) on cell performance is carried out. It is seen that the increment in C-rates strongly influences the cell performance. It is found that the average capacity increases by 44% at the higher C-rate, i.e., 5C when the porosity increases logarithmically. On the contrary, sinusoidal variation in porosity yields in the worst cell performance. The findings of the present study bear utility toward designing an efficient battery system that can operate for a higher number of cycles with minimal power dissipation density and can fit into the ultrafast charging technique.