Abstract
Long-range electric vehicles (EVs) require high-energy-density batteries that also meet the power demands of high current charge and discharge. Ultra-thick (>100 μm) Lithium-ion battery electrodes are critical to enable this need, but slow ion transport in conventional uniform electrodes (UEs) reduces battery capacity at increasing charge/discharge rates. We present a 3D computational analysis on the impact of structured electrode (SE) and graded electrode (GE) geometries on the discharge rate capability of ultra-thick graphite|LiNi0.6Mn0.2Co0.2O2 (NMC-622) battery cells based on the footprint of a commercial EV pouch cell. SE cathodes with either a “grid” or “line” geometry and GEs with two layers of porosity were modeled. Based on the results of 230 models, we found that the electrolyte volume fraction is a key parameter that impacts capacity improvements in UEs, GEs, and SEs at 2 C-6 C discharge rates. SEs have the greatest discharge rate capability, outperforming GEs and UEs due to reduced Lithium-ion concentration gradients across the electrode thickness, which mitigates electrolyte depletion at high rates. The best SE model has a “grid” geometry with gravimetric and volumetric energy density improvements of 0.9%-4% at C/2-2 C and 18%-24% at 4 C-6 C relative to UEs.
Original language | English |
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Article number | 010513 |
Journal | Journal of the Electrochemical Society |
Volume | 172 |
Issue number | 1 |
DOIs | |
State | Published - Jan 1 2025 |
Keywords
- electric vehicle
- graded electrodes
- pouch cell
- structured electrodes
- theory and modelling
- thick electrodes