A Mathematical Model for Li-Air Battery Considering Volume Change Phenomena

Li-air battery has the potential to be the next generation energy storage device because of its much higher energy density and power density. However, the development of Li-air battery has been hindered by a number of technical challenges such as passivation of cathode, change in effective reaction area, volume change during charge and discharge, etc. In a lithium-air cell, the volume change can take place due to Li metal oxidation in anode during charge as well as due to the solubility of reaction product (lithium peroxide) in the electrolyte at cathode. In this study, a mathematical model is developed to study the performance of lithium-air batteries considering the significant volume changes at the anode and cathode sides using moving boundary technique. A numerical method was introduced to solve moving boundary problem using finite volume method. Using this model, the electric performance of lithium-air battery is obtained for various load conditions. Numerical results indicate that cell voltage drops faster with increase in load which is consistent with experimental observations. Also, the volume changes significantly affect the electric performance of lithium-air cell.