Multi-Particle Model for a Commercial Blended Lithium-Ion Electrode

A mathematical model is presented to describe the electrochemical performance of a LiNi1/3Mn1/3Co1/3O2−LiMn2O4 (NMC-LMO) blended cathode obtained from a commercial lithium-ion battery. The model accounts for the multiple particle sizes of the active materials in terms of three distributions: one for LMO particles, one for NMC primary and one for NMC secondary particles which likely are agglomerates of primary particles. The good match between the simulated and experimental galvanostatic discharge and differential-capacity curves supports the assumption that the secondary particles are nonporous under conditions where currents of 2C and below are applied. A thermodynamically consistent equation for diffusive flux is used to describe transport across the active particles. The corresponding thermodynamic factors are estimated from the equilibrium potentials of the active materials present in the electrode, while the particle size distribution and effective electronic conductivities of each component have been directly measured. Since the model is able to accurately describe the utilization of the various particle sizes and determine the contribution of each component at different discharge rates, it can serve as a useful tool for customizing the designs and predicting the discharge profiles of electrode blends made up of different active materials having a range of particle sizes.