Electrode Designs of Lithium Ion Batteries Utilizing the Simulation of Porous Structures

Abstract

The development of high capacity anode active materials for lithium-ion batteries has been hindered by the expansion of these materials during charging, and it is currently unclear how electrode design should be modified to account for this. We herein investigate the effects of the volumetric expansion ratio of active materials on charge capacity using numerical simulations that consider the expansion of these active materials. Charging properties were calculated using equations based on the porous electrode theory and expressing the parameter changes caused by expansion. The charge capacity was found to vary with both the C-rate and with structure conditions when compared with the case where expansion did not take place “no expansion” case depending on C-rate and structure conditions. In this context, with an electrode thickness of 60 μm, an active material volume fraction of 0.6, and a volumetric expansion ratio of 2.0, the capacity decreased to 27% at 10 C. These results indicate the importance of electrode design in the presence of expanding active materials, and also suggest that it is possible to quantitatively design porous electrodes using this calculation method.