An electrolyte, which carries charge between a battery’s cathode and anode, is a liquid in common commercial batteries, which makes them potentially flammable, especially in lithium-ion form. A solid-state conductor, which has the potential to become an electrolyte, would be far more fire-resistant. A resultant solid-state battery is the Holy Grail, with enormous efforts in industry dedicated to its development. Which brings us to researchers at DOE’s Lawrence Berkeley National Laboratory and Argonne National Laboratory, who were working on a magnesium battery that offers higher energy density than lithium. They were stymied by the dearth of good options for a liquid electrolyte, most of which tend to be corrosive against other parts of the battery.

The team of U.S. Department of Energy (DOE) scientists at the Joint Center for Energy Storage Research say they have discovered a combination of both—the fastest magnesium-ion solid-state conductor to date. The discovery is said to be a major step toward making solid-state magnesium-ion batteries that are both energy dense and safe. The material they came up with, magnesium scandium selenide spinel, has magnesium mobility comparable to that of solid-state electrolytes for lithium batteries.

The research team believes there is a long way to a viable battery, and there is still work to do to reduce the material’s electron leakage. However, it’s the first demonstration that solid-state materials can be made with really good magnesium mobility. Additionally, the research identified two related fundamental phenomena that could significantly affect the development of magnesium solid electrolytes in the near future, namely, the role of anti-site defects and the interplay of electronic and magnesium conductivity.

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