Modeling Volume Change in Dual Insertion Electrodes

A mathematical model is presented that incorporates the dimensional and porosity changes in porous electrodes caused by volume changes in the active material during intercalation. Porosity and dimensional changes in an electrode can significantly affect the resistance of the battery during cycling. In addition, volume changes generate stresses in the electrode, which can lead to premature failure of the battery. Here, material conservation equations are coupled with the mechanical properties of porous electrodes to link dimensional and porosity changes to stresses and the resulting resistances that occur during the intercalation processes. Several different battery casings are examined in order to generate summary figures to aid in battery design. The associated stress, strain, porosity and resistance is predicted and discussed in relation to battery performance.