Modeling and simulation of inhomogeneities in a 18650 nickel-rich, silicon-graphite lithium-ion cell during fast charging

Abstract

Recent high-energy lithium-ion batteries contain highly densified electrodes, but they are expected to endure fast charging without safety compromises or accelerated aging. To investigate fast charging strategies, we use a multi-dimensional model consisting of several newman-type electrochemical models (p2D) coupled to an electrical-thermal cell domain model. Open-circuit potential, infrared thermography and calorimetry experiments of a high-energy 18650 NMC-811/SiC lithium-ion cell are used for model parameterization and validation. First, a single p2D model is used to compare the charging rate capabilities of NMC-811/SiC and NMC-111/graphite cells. We assess the modeling error of the single p2D model relative to the multi-dimensional model as a function of tab design. The multi-dimensional model is then used to study different tab and electrode designs regarding their susceptibility to lithium plating, which is evaluated based on local anode overpotential and local temperature. High-rate charging current profiles that minimize the risk of lithium plating are derived by implementing an anode potential threshold. We show that a state of charge beyond 60% can be reached in less than 18 min.