Implementing Realistic Geometry and Measured Diffusion Coefficients into Single Particle Electrode Modeling Based on Experiments with Single LiMn2O4 Spinel Particles

Abstract

Realistic geometry and diffusion coefficients were measured from a single particle LiMn2O4 electrode and implemented into a three-dimensional multiphysics simulation of a single particle, in order to demonstrate a novel approach to electrode material study. Dispersed particles were used, and electrochemical techniques and atomic force microscopy were performed on isolated single particles. Diffusion coefficients measured from both cyclic voltammetry and the potentiostatic intermittent titration technique ranged between 3.2 × 10−12 and 1.2 × 10−11 cm2/s, which was similar to values measured from thin film LiMn2O4 electrodes. The trend of diffusivity change over potential (versus lithium counter electrode) was similar to those observed from both composite cells and thin film electrodes. The measured diffusion coefficients were then used in simulation of discharge of the irregular particle, by importing the particle morphology into a finite element simulation, in order to simulate intercalation-induced stress generation. Simulation results showed a higher maximum stress generation due to altering diffusivity around the peak current potentials and high local stress concentration on the sharply indented surface area, suggesting that particle irregularities are important in studying both electrochemical performance and local failure mechanisms in cathode materials.