Fast-charging capability versus energy density – a parametric study using a multi-dimensional lithium-ion cell model

As a result of the steadily increasing market share of battery-electric vehicles, the demands on the battery system in terms of range and fast-charging capability are becoming tougher in order to meet customer needs. Depending on the design of the cell and the electrodes in particular, the lithium-ion cell can be optimized in terms of its energy and power density, but the two parameters are generally in conflict. This paper therefore addresses the influence of electrode thickness, porosity, and porosity-layered electrodes on fast-charging capability and energy density. For this purpose, a three-dimensional electrical and thermal model is implemented, which is parameterized and validated based on a high-energy cylindrical cell (NMC 811—Graphite-Si). To simulate the electrical behavior, a half-cell Equivalent Circuit Model is used. Starting from the reference cell, different electrode structures are investigated in terms of their fast-charging capability and energy density with the objective of finding an optimal combination of energy and power density.