Intercalation-Induced Stress and Heat Generation within Single Lithium-Ion Battery Cathode Particles

Intercalation-induced stress and heat generation inside Li-ion battery cathode (LiMn2 O4) particles under potentiodynamic control are simulated in this paper. We combined analyses of transport and kinetics in determining resulting stresses, which arise from concentration gradients in cathode particles, and heat generation. Two peaks in boundary reaction flux, and resulting stresses, were determined from the modeling of electrochemical kinetics and diffusion, using intrinsic material properties (resulting in two plateaus in the open-circuit potential) and the applied potential. Resistive heating was identified as the most important heat generation source. To probe the impact of the particle shape (equivalent radius and aspect ratio of an ellipsoidal particle) and the potential sweep rate on stress and heat generation, a surrogate-based analysis was also conducted. The systematic study showed that both intercalation-induced stress and time-averaged resistive heat generation rate increase with particle radius and potential sweep rate. Intercalation-induced stress increases first, then decreases as the aspect ratio of an ellipsoidal particle increases, whereas time-averaged resistive heat generation rate decreases as aspect ratio increases. This surrogate-based analysis suggests that ellipsoidal particles with larger aspect ratios are preferred over spherical particles, in improving battery performance when stress and heat generation are the only factors considered. © 2008 The Electrochemical Society.