Understanding Performance Limitations to Enable High Performance Magnesium-Ion Batteries

Abstract

© The Author(s) 2016. A mathematical model was developed to investigate the performance limiting factors of Mg-ion battery with a Chevrel phase (MgxMo6S8) cathode and a Mg metal anode. The model was validated using experimental data from the literature [Cheng et al., Chem. Mater., 26, 4904 (2014)]. Two electrochemical reactions of the Chevrel phase with significantly different kinetics and solid diffusion were included in the porous electrode model, which captured the physics sufficiently well to generate charge curves of five rates (0.1C-2C) for two different particle sizes. Limitation analysis indicated that the solid diffusion and kinetics in the highervoltage plateau limit the capacity and increase the overpotential in the Cheng et al.'s thin (20-μm) electrodes. The model reveals that the performance of the cells with reasonable thickness would also be subject to electrolyte-phase limitations. The simulation also suggested that the polarization losses on discharge will be lower than that on charge, because of the differences in the kinetics and solid diffusion between the two reactions of the Chevrel phase.