A computational analysis of effects of electrode thickness on the energy density of lithium-ion batteries

Abstract

Elevated energy density is a prime requirement for many lithium-ion battery (LIB) applications, including electric vehicles (EVs). At the cell level, the enhanced energy density of LIBs is achievable by designing thicker electrodes, which decreases the weight of the inactive materials. This work proposed a reduced order electrochemical model (ROEM), which is an extended single particle model (extended SPM), by incorporating the existing order reduction techniques of Pseudo-Two-Dimensional (P2D) model. The proposed model was used to predict the energy density values of a nickel cobalt manganese (NCM) cell with respect to the cathode thickness. The validation of the model was performed by using MATLAB at 0.05C, 1C, 2C, 3C and 5C rates by comparing the simulation results with the experimental data obtained from the Stanford Energy Control Laboratory. The verified model was then used to simulate the effect of varying thicknesses of the cathode on energy density of the NCM cell at C/5, C/2, 1C, and 2C rates of discharge. The simulation results illustrate that increasing the cathode thickness has a profound positive impact on the energy density of the cell. The prediction of the model demonstrates a total of around 20 % increase in energy density for the increment of cathode thickness from 75 μm to 600 μm. The proposed model can replicate energy density for thicker electrodes up to 2C rate reasonably correctly. However, the incorporation of thermal characteristics and other influential parameters of LIB cells into the proposed model can yield a better prediction of energy density of thicker electrodes at higher C-rates, which is recommended for further study.