Alloying is one of the effective approaches to boost the discharge property of magnesium (Mg) anodes for primary Mg-air batteries and recently micro-alloying is highly recommended at the aim of developing advanced primary Mg system. In this study, micro-alloyed extruded Mg0.5Zn0.2Ge (in wt.%) alloy is evaluated as an anode candidate for primary Mg-air batteries in both half-cell and Mg-air full cell configurations, in comparison with commercially accepted Mg anodes, typified by as-cast HP Mg and extruded AZ31 alloy. The corrosion behavior at open circuit potential (OCP) condition of the three materials is also compared through electrochemical tests. Mg0.5Zn0.2Ge alloy displays the most negative OCP value and the highest corrosion resistance at OCP. During discharge, Mg0.5Zn0.2Ge anode exhibits low wasteful-discharge rate and homogeneous dissolution that gives rise to the absence of “chunk effect”. Consequently, the anodic efficiency and specific capacity of Mg0.5Zn0.2Ge anode are superior to those of HP Mg and AZ31 anodes, e.g. 57.3% and 1257 mAh g⁻¹ at 1 mA cm⁻². Additionally, Mg-air battery based on Mg0.5Zn0.2Ge anode offers higher cell voltage and specific energy than those assembled with HP Mg and AZ31 anodes, which can be further optimized by addition of electrolyte additives. Therefore, micro-alloyed Mg0.5Zn0.2Ge alloy can serve as a promising candidate for anode material of primary Mg-air batteries.

The interaction between organic molecules and biomaterial surfaces determines the fate of biomaterials during their service life, which is also the research hotspots in the field of biomaterials. To understand the mechanism of protein interaction with magnesium (Mg) degradation, alloying elements, immersion time, protein concentration and surface conditions have been previously considered for the effect of proteins on Mg degradation. However, fluid flow, as one of the critical factors, drew little attention in this case. In the present study, the effect of bovine serum albumin (BSA) and fetal bovine serum (FBS) on Mg degradation was compared under static and dynamic conditions. The results revealed that both BSA and FBS slightly decreased the degradation rate of Mg in Hanks’ balanced salt solution (HBSS) under static immersion due to the protein adsorption and the formation of a Ca/P-rich top layer on Mg surface, whereas under dynamic flow condition the degradation of Mg was significantly accelerated in the presence of BSA or FBS. The reasons seemed to stem from the weakened protein adsorption on Mg surface in this case and the dynamically enhanced interaction between proteins and ions/products in solutions, which largely weaken the combination of the top Ca/P-rich layer with the inner corrosion product layer. These results highlight the importance of testing conditions for Mg characterization in vitro and the synergistic effect between different parameters on Mg degradation.