Modeling of Silicon-Air Batteries

Abstract

In order to improve the lifetime and performance of an electric drive train system, one of the most challenging tasks is to improve the performance of the electrochemical energy storage device in terms of the power and energy density. The energy density of current electrochemical concepts, such as Li-ion batteries, is still far from meeting all demands due to technological and thermodynamical limitations. Therefore, new electrochemical energy storage concepts with enhanced energy density, such as metal-air batteries, are currently being investigated. Silicon-air batteries, a recent concept of metal-air batteries, have been researched over the past few years. From a thermodynamic point of view, the silicon-oxygen couple is very promising and attractive. The theoretical energy density of silicon-air batteries ( ) are close to lithium-air batteries ( ) which is the highest capacity among all the batteries. The aim of this work is to model primary silicon-air batteries by computationally to evaluate the performance of the battery and improve the understanding of the system. In that respect, we developed a mathematical model of the battery on the basis of the mechanisms discussed in previous experimental studies. Our mathematical model is based on the electrochemical processes including reactions, transport mechanisms, oxygen dissolution, volume conditions, and nucleation and growth processes. Finally, we investigate remarkable effect of water addition into the electrolyte with our simulations. We discuss our results in terms of nucleation and growth in the battery, half-cell potentials of the electrodes, spatial distribution of crystallization in the electrode pores, discharge of the battery at various water contents, and discharge of the battery at various discharge currents.