Modeling the effect of electrode thickness on the performance of lithium-ion batteries with experimental validation

Abstract

Manufacturing process for composite electrodes in lithium-ion batteries generally results in non-uniform micro-structure geometrical distribution in the through-thickness direction of a porous electrode. Inhomogeneity of the porous electrode thus affects the lithium ions transport in the electrolyte and their diffusion in the active materials. Quantifying the relationship between mass transport-related parameters and the electrode thickness is very important for studying the effect of the electrode thickness on the performance of lithium-ion batteries. The objective of this work is to study how the Lix(Ni1/3Mn1/3Co1/3)O2 (NMC111) electrode thickness affects the battery performance by developing an improved physics-based electrochemical model. In this model, the Bruggeman coefficient and the effective diffusion coefficient of NMC111 cathode with various thicknesses ranging from 31 μm to 130 μm are estimated by comparing simulation results with experimental data. The proposed electrochemical model is validated experimentally for cells with various electrode thicknesses. The simulation results indicate that increasing electrode thickness reduces the rate capabilities of lithium-ion batteries. The reason is discussed by analyzing the ohmic and diffusion limitation for cells will various electrode thicknesses under different discharge C-rates.