However, results from simulations based on the porous electrode model are known to diverge from experimental results under relatively demanding operating conditions (see, for instance, [1]) that can arise during typical electric vehicle use. This might be the consequence of the spatial averaging approach of the porous electrode method, as electrode microstructure might have a significant influence on transport processes and cell performance. In order to explore this possibility, we have performed traditional porous electrode model simulations and corresponding electrochemical simulations based on the microscale electrode structure.
Nickel manganese cobalt oxide (NMC) electrodes were fabricated and incorporated into half-cells, from which discharge curves were obtained. Electrode parameters were used to construct simulations based on the porous electrode model, and an optimization scheme was used to minimize discrepancies between simulation and experimental results.
Samples of the same uncycled NMC electrode material were then imaged at the X-ray microtomography beamline of the Advanced Light Source (ALS). Three-dimensional reconstructions were transformed into spatial domains, on which direct numerical simulations were performed to obtain discharge curves. These simulations preserved spatial detail but involved much higher computational costs than those based on the porous electrode model.
We will present results from these microscale and macroscale simulations, exploring reasons for discrepancies between the two models and discussing present shortcomings with respect to experimental results.
[1] M. Doyle, J. Newman, A. S. Gozdz, C. N. Schmutz, and J.-M. Tarascon, J. Electrochem. Soc. 1996, vol. 143, issue 6, pp. 1890-1903