Lattice Boltzmann simulation of ion and electron transport during the discharge process in a randomly reconstructed porous electrode of a lithium-ion battery

Abstract

Rechargeable lithium–ion batteries (LIBs) have improved significantly over the past 20 years; however, the micro-scale working mechanism of these batteries, especially the influence of electrode microstructures on battery performance, still requires further study. The relationship between the electrode microstructure and battery performance is studied in detail by developing a two-dimensional (2D) lattice Boltzmann model to reveal the ion and electron transport within an LIB porous electrode. The present model is established by using randomly reconstructed electrode geometry and the coupling of the electrochemical reaction and ion and electron transport under complex boundary conditions. The influences of the micro-scale morphological features of the battery electrode on the local lithium concentration distribution, electric potential and macroscopic discharge performance are revealed. The randomness of the particle distribution and particle shape result in a heterogeneous distribution of the lithium concentration and electrode potential. In electrode particles, lithium exchanges are enhanced for small particles and improved at the edges and corners for large irregular particles. Regions with low lithium concentration produce a high electric potential. A large particle size and low porosity in an anode improve battery performance. Likewise, a small particle size and high porosity in a cathode also improve battery performance.