Gas-Evolution Induced Volume Fraction Changes and Their Effect on the Performance Degradation of Li-Ion Batteries

Li-ion batteries swell due to gas evolution that results from decomposition of the electrolyte and from reaction with impurities. To study dimensional changes in Li battery cells, we derive a model for gas-evolution induced volume fraction changes in both electrolyte and inert material phases in composite Li-ion electrodes. The nonlinear increase in cell resistance is explained using volume fraction changes within the context of physics-based modeling. The simulation results given here are also used to map the effects of volume fraction changes on the discharge curve and on heat generation. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3458649] All rights reserved.