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Japanese researchers have developed a new cathode material for rechargeable magnesium (RMB) batteries in the form of rock salt oxide. This new material allows for efficient loading and unloading even at low temperatures.
Rechargeable magnesium (RMB) batteries have attracted significant interest as energy storage devices beyond lithium-ion batteries due to their potentially high energy density and the abundance of magnesium in the Earths crust. However, the commercialization of this type of technology has been slowed by the lack of suitable cathode materials.
Now, researchers at Tohoku University (Japan) have developed a new cathode material for RMBs, taking advantage of an improved rock salt structure, which allows efficient charging and discharging even at low temperatures.
Their study shows a considerable improvement in the diffusion of magnesium within a rock salt structure, a critical advance since the density of atoms in this configuration had previously prevented magnesium migration.
By introducing a strategic mixture of seven different metallic elements (Mg0.35Li0.3Cr0.1Mn0.05Fe0.05Zn0.05Mo0.1O), the researchers created a crystal structure abundant in stable cationic vacancies, which facilitated the insertion and extraction of magnesium. They reported that the extraction of lithium cations in the first charge gives rise to a substantial amount of vacant cations in the rock salt structure, which facilitates the diffusion of magnesium (Mg) in subsequent cycles.
This represents the first use of rock salt oxide as a cathode material for RMBs. The development also addresses a key limitation of RMB: the difficulty of magnesium transport within solid materials.
Until now, high temperatures have been necessary to improve the mobility of Mg in conventional cathode materials, such as those with a spinel structure. However, the material presented by Tohoku University researchers supposedly works effectively at 90°C, demonstrating a significant reduction in the required operating temperature.
The researchers reported that the new material produced a reversible capacitance of about 90 mA h g-1 at a current density of 10.4 mA g-1 with a potential of about 2.0 V versus Mg2+/Mg at 90 °C , a relatively low temperature compared to previously reported spinel oxide cathodes, which operated at 150 °C.
According to Tomoya Kawaguchi, lead author of the research, “magnesium batteries, with the new cathode material developed, are set to play a fundamental role in various applications, such as grid storage, electric vehicles and portable electronic devices, contributing to the global shift towards renewable energies and the reduction of the carbon footprint.”
The research results are analyzed in “ Securing cation vacancies to enable reversible Mg insertion/extraction in rocksalt oxides ,” published in the Journal of Materials Chemistry A. |
