Mg and its alloys show high potential to be applied as implant materials due to their superior properties like biodegradability, bioactivity, biocompatibility, and suitable mechanical behaviors. Nevertheless, the fast and uncontrolled degradation of Mg alloys in biological environment severely restricts their wide applications as biomedical materials. In comparison with alloying, surface coatings can not only improve corrosion resistance but also impart other bio-functional properties to achieve diverse clinical requirements. This review analyzes and summarizes the most recent developments in popular coating technologies, including micro-arc oxidation, electrophoretic deposition, chemical conversion, anodic oxidation, layered double hydroxide, and sol-gel coatings. Considering inevitable damages under complex service conditions, smart self-healing coatings are also introduced in each coating technology. The existing issues and future perspectives are finally discussed to facilitate applications of Mg alloys as biomedical materials in the medical industry.

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.

Coating technologies are a commonly used way to protect metals against corrosion. However, with more and more severe service environments of materials, many protective coating systems often are not environmentally friendly or toxic as in the case of chromates. Based on the world’s abundant ideal magnesium (Mg) and its alloy, the smart self-healing anticorrosive coating can autonomously restore the damaged part of the coating according to the environmental changes, strengthen the corrosion protection ability, and prolong its service life. This paper reviews the research progress of smart self-healing coatings on Mg alloys. These coatings mostly contain suitable corrosion inhibitors encapsulated into micro/nano containers. Moreover, the different self-healing mechanisms and functionalities of micro/nano containers are discussed. The micro/nano containers range from inorganic nanocontainers such as mesoporous nanoparticles (silica (SiO₂), titanium dioxide (TiO₂), etc.), over inorganic clays (halloysite, hydrotalcite-like, zeolite), to organic nanocontainers such as polymer microcapsules, nanofibers, chitosan (CS) and cyclodextrin (CD), as well as, carbon materials such as graphene and carbon nanotubes and hybrids such as metal organic frameworks. The functioning of micro/nano containers can be divided in two principal groups: autonomous (based on defect filling and corrosion inhibition) and non-autonomous (based on dynamic bonds and shape memory polymers). Moreover, multi functionalities and composite applications of various micro/nano containers are summarized. At present, significant progress has been made in the preparation methods and technologies of micro/nano containers. Achieving long-term self-healing properties of coatings sensing of coating failure and early warning after self-healing function failure can be expected as the main development direction of self-healing corrosion protection coatings in the future.

In this work, plasma electrolytic oxidation (PEO) coatings were produced on magnesium alloy AZ31 in aluminate, silicate and phosphate-based electrolytes, and followed by hydrothermal treatments in order to synthesis layered double hydroxides (LDHs) based nanocontainers. LDHs synthesis was done in three different growth solutions (deionized water, sodium nitrate and aluminum nitrate containing solution). In frame of this work it was shown, that it was difficult to form LDHs on Si-based PEO coating, due to more stable silicate phases in comparison with aluminate and phosphate phases in respective PEO coatings. The obtained hybrid LDH/PEO coatings were characterized using SEM, EDS and GDOES, and then the corrosion protection was further investigated by EIS. Based on the obtained results, it was confirmed that, the hydrothermal treatments in Al³⁺ containing solution played an important role on overall corrosion resistance for phosphate and silicate-based PEO coatings, but not for Al-based PEO coatings.