Influence of Intra-Particle Concentration Gradients and Lithium Plating on the Thickness Change of a Lithium-Ion Pouch Cell

Abstract

Lithium plating is a critical factor that limits the fast-charging capabilities of lithium-ion batteries. Here we investigate the contributions of lithium plating and intra-particle lithium concentration gradients to the rate-dependent thickness change observed experimentally in a commercial high-power lithium-ion pouch cell with graphite negative electrode and a blend of lithium nickel cobalt aluminum oxide and lithium cobalt oxide positive electrode. This cell exhibits a thickness “overshoot” during charging at high C-rates, which partially recovers during the constant-voltage (CV) phase. We utilize a previously-developed pseudo-three-dimensional (P3D) thermo-electro-mechanical model to simulate these effects and validate the model against experimental data. Our findings show that intra-particle lithium concentration gradients significantly contribute to the thickness change at moderate C-rates due to the nonlinear volume expansion of graphite. At higher C-rates, lithium plating becomes a major factor, contributing both reversibly and irreversibly to the thickness change. A model including these effects accurately captures experimentally-observed behavior, providing insights into the complex thermo-electro-mechanical interactions inside the electrodes. This understanding is crucial for optimizing in operando lithium plating detection methods relying on thickness or mechanical stress measurements.