This study investigates the effectiveness of salicylate (SAL) as an electrolyte additive on the discharge behavior of high-purity (HP) Mg anode in an aqueous half-cell system, using an integrated approach of mathematical modeling and experimental analysis. A finite element-based model is developed to elucidate the key mechanisms by which SAL influences the voltage profile and pH. Systematic electrochemical measurements, especially intermittent discharge tests combined with electrochemical impedance spectroscopy (EIS), demonstrate that SAL can enhance initial voltage stability of HP Mg anode. Moreover, the model incorporates the SAL-Mg complexation factor to describe the role of SAL in modifying the deposit film on HP Mg surface. The agreement between model predictions and experimental observations suggests that SAL facilitates the formation of compact Mg(OH)₂ deposits and sustains a favorable pH environment within the half-cell compartment. This integrated approach provides new insights into understanding and optimizing additive effects for Mg-air batteries.

The voltage drop appearing at Mg anode-electrolyte interface is a critical issue for the battery power and energy density of aqueous primary Mg-air batteries. The respective voltage loss is typically assigned to the deposits layer forming on the anode surface during discharge. In this work, we experimentally and computationally investigate the critical factors affecting the voltage drop at Mg anode towards a deeper understanding of the contribution of deposit and its growth. A two-dimensional (2D) mathematical model is proposed to compute the voltage drop of Mg-0.15Ca wt.% alloy (Mg-0.15Ca) by means of a semi-empirical formulas and experiments-based modification model, considering the effect of discharge current density, the negative difference effect (NDE) and surface deposits layer itself. This model is utilized to simulate the discharge potential of the anode at predefined experimental current densities. The computed voltage drop (half-cell voltage) is in good agreement with the experimental value. The applicability of the mathematical model is successfully validated on the second material (namely high-purity Mg).