Mg-air batteries, with their high theoretical energy density, low cost, and eco-friendliness, offer broad application prospects. Nonetheless, challenges such as corrosion, uneven dissolution of the Mg anode, and the adherence of discharge products impair the utilization efficiency of Mg anodes and reduce the output voltage of these batteries. The electrolyte plays a pivotal role in the interface structure and electrode reactions within Mg-air batteries, directly affecting their performance. This review focuses on the latest advancements in electrolytes for Mg-air batteries, covering various aspects including aqueous electrolytes and their additives, non-aqueous electrolytes, as well as electrolytes for rechargeable Mg-air batteries, elucidating the underlying mechanisms. In addition, potential avenues for future research in Mg-air battery electrolytes are outlined, providing a comprehensive perspective on the development of high-performance Mg-air batteries.

The quest for high-energy-density magnesium-air batteries is hindered by the efficiency-voltage trade-off, ultimately leading to an unsatisfactory energy density. Here, we effectively mitigate the inherent efficiency-voltage trade-off by introducing a novel anode material, specifically, Mg-0.5Sn-0.5In-0.5Ga. This anode demonstrates exceptional anodic efficiency, achieving 60.5 ± 2.5% at 1 mA cm⁻², 65.3 ± 2.7% at 10 mA cm⁻², and 71.4 ± 1.2% at 20 mA cm⁻². Furthermore, the discharge voltage is significantly enhanced, reaching 1.76±0.01 V at 1 mA cm⁻², 1.44±0.02 V at 10 mA cm⁻², and 1.21±0.08 V at 20 mA cm⁻². Consequently, our newly developed anode exhibits a remarkable energy density of 2312±98 W h kg⁻¹, placing it among the top-performing magnesium anodes documented in the literature. Density functional theory calculations and experimental investigations have unveiled that the exceptional performance can be attributed to the inhibition of water reduction, facilitated by the hybridization between solute atoms and neighboring Mg atoms. Furthermore, the activation of the second phase, introducing additional galvanic couples, significantly contributes to this performance. This study presents valuable insights that can guide the design of novel anodes, contributing to the advancement of high-performance magnesium-air batteries.

Hot deformation with high strain rate has been paid more attention due to its high efficiency and low cost, however, the strain rate dependent dynamic recrystallization (DRX) and texture evolution in hot deformation process, which affect the formability of metals, are lack of study. In this work, the DRX behavior and texture evolution of Mg-8Gd-1Er-0.5Zr alloy hot compressed with strain rates of 0.1 s⁻¹, 1 s⁻¹, 10 s⁻¹ and 50 s⁻¹ are studied, and the corresponding dominant mechanisms for DRX and texture weakening are discussed. Results indicated the DRX fraction was 20% and the whole texture intensity was 16.89 MRD when the strain rate was 0.1 s⁻¹, but they were 76% and 6.55 MRD, respectively, when the strain rate increased to 50 s⁻¹. The increment of DRX fraction is suggested to result from the reduced DRX critical strain and the increased dislocation density as well as velocity, while the weakened whole texture is attributed to the increased DRX grains. At the low strain rate of 0.1 s⁻¹, discontinuous DRX (DDRX) was the dominant, but the whole texture was controlled by the deformed grains with the preferred orientation of {0001}⊥CD, because the number of DDRX grains was limited. At the high strain rate of 50 s⁻¹, continuous DRX (CDRX) and twin-induced DRX (TDRX) were promoted, and more DRX grains resulted in orientation randomization. The whole texture was mainly weakened by CDRX and TDRX grains, in which CDRX plays a major role. The results of present work are significant for understanding the hot workability of Mg-RE alloys with a high strain rate.

Alloying seriously deteriorates the thermal conductivity of magnesium (Mg) alloys, thus, restricts their applications in the fields of computer, communication, and consumer products. In order to improve the thermal conductivity of Mg alloys, adding carbon nanotube (CNT) combined with aging treatment is proposed in this work, i.e. fabricating the D-CNT (a kind of dispersed CNT) reinforced ZK61 matrix composite via powder metallurgy, and conducting aging treatment to the composite. Results indicate the as-aged ZK61/0.6 wt.% D-CNT composite achieved an excellent thermal conductivity of 166 W/(mK), exhibiting 52.3% enhancement in comparison with matrix, as well as tensile yield strength of 321 MPa, ultimate tensile strength of 354 of MPa, and elongation of 14%. The simultaneously enhanced thermal conductivity and mechanical performance are mainly attributed to: (1) the embedded interface of the D-CNT with matrix and (2) the coherent interface of precipitates with matrix. It is expected the current work can provide a clue for devising Mg matrix composites with integrated structural and functional performances, and enlarge the current restricted applications of Mg alloys.

In this investigation, a high-strength Mg-12Gd-1.0Er-0.5Zr (wt.%) alloy sheet was produced by hot extrusion (HE) and subsequent hard-plate rolling (HPR) at different temperatures. The results indicate that the microstructures of these final-rolled sheets are inhomogeneous, mainly including coarse deformed grains and dynamic recrystallized (DRXed) grains, and the volume fraction of these coarse deformed grains increases as the rolling temperature increases. Thus, more DRXed grains can be found in R-385 °C sheet, resulting in a smaller average grain size and weaker basal texture, while the biggest grains and the highest strong basal texture are present in R-450 °C sheet. Amounts of dynamic precipitation of β phases which are mainly determined by the rolling temperature are present in these sheets, and its precipitation can consume the content of Gd solutes in the matrix. As a result, the lowest number density of β phase in R-450 °C sheet is beneficial to modify the age hardening response. Thus, the R-450 °C sheet displays the best age hardening response because of a severe traditional precipitation of β' (more) and β_H/β_M (less) precipitates, resulting in a sharp improvement in strength, i.e. ultimate tensile strength (UTS) of ~ 518 ± 17 MPa and yield strength (YS) of ~ 438±18 MPa. However, the elongation (EL) of this sheet reduces greatly, and its value is ~ 2.7 ± 0.3%. By contrasting, the EL of the peak-aging R-385 °C sheet keeps better, changing from ~ 4.9 ± 1.2% to ~ 4.8 ± 1.4% due to a novel dislocation-induced chain-like precipitate which is helpful to keep good balance between strength and ductility.

The vulnerable corrosion resistance of Mg alloys is regarded as one of the main disadvantages restricting their application, while it can be used as an extraordinary specialty in some particular fields, such as petroleum exploitation and medicine. In recent years, many Mg alloys with high corrosion rate and high strength have been developed for fracturing temporary plugging tools in the oil exploitation. This review briefly introduces the performance requirements of the degradable fracturing tools classified into mechanical and corrosion properties. Recent progress on corrosion behavior of degradable Mg-Al, Mg-Zn, Mg-RE alloys and Mg matrix composites is then summarized and discussed. Finally, the factors influencing the degradation rate of Mg alloys are analyzed and divided into secondary phase, texture, dislocation, grain size and surface film. From the summary, it can be found that addition of Ni or Cu to the degradable Mg alloys is a common and effective method to enhance the degradation rate due to increasing the amount of secondary phases and deteriorating the corrosion product layers. For the as-extruded degradable Mg alloys, grain size, texture and dislocation are the key factors affecting the corrosion rate under different processing conditions. We expect this review is helpful for those who are working on developing Mg-based functional materials with superior degradation rate.

In this study, we successfully developed a low RE containing Mg-3Y-2Gd-1Nd-0.5Zr (wt%) alloy with high strength-ductility synergy by combined processes of hot extrusion, hot rolling and ageing. This alloy exhibits an excellent strength-ductility balance (UTS of 345 ± 2.0 MPa, TYS of 301 ± 5.0 MPa and EL of 9.2 ± 1.9%), which is better than that of many Mg-RE wrought alloys with higher RE concentration and even comparable to that of 6061 Al wrought alloy. A long-range chain-like structure consisting of β^′ phase, β_H phase, β_M phase and zig-zag atomic columns is observed for the first time in the studied alloy. The combined process of hot extrusion and hot rolling boosts the formation of deformed grains and low angle grain boundaries, and makes the deformed grains dominate in the alloy strengthening. Under this circumstance, the following ageing generates a novel heterogeneous structure comprising the long-range chain-like structure with broad interparticle spacing and the spacious precipitate-free zones in the deformed grains, which plays a key role in the concurrent strengthening and toughening of the alloy. The present study demonstrates that the deformed grains with long-range chain-like structures and precipitate-free zones is desirable microstructure for the low RE containing Mg alloys to achieve high strength-ductility synergy.