Kinetics accommodation in Li-ion mechanistic modeling

Abstract

The ongoing extension of usage for lithium-ion cells and packs in both stationary and mobile applications necessitates a steeply increasing need for comprehensive tools and models to diagnose and prognose cell performance. Among those, a simple mechanistic framework using electrode half-cell data has gained a lot of attention due to its ability to synthesize the terminal voltage of battery cells based on the individual electrode potentials. Although proven valid in the quantification of cell degradation, path dependence of aging and cell-to-cell variations, the application of the model framework has been restricted so far mostly to voltage profiles recorded at low C-rates.For use in battery management systems, this limitation should preferably be overcome to enable on-board diagnostics from medium to high rates and at any temperature. For this reason, this study aims at an advanced exploration of the cell's kinetics and how it can be compensated within the mechanistic framework. This was done by investigating two previously proposed parameters, the ohmic resistance increase and the rate degradation factor.This study indicates that both parameters follow a well-defined Arrhenius dependency allowing to map the voltage behaviour of the underlying half-cell to the measured full cell data at different rates and temperatures.