Japanese Scientists Prove Magnesium Can Be A Safer And More Energy-Dense Battery Element Than Lithium

Electric Vehicles / 16 Comments

This could make electric vehicles safer and able to drive further.

Scientists at the Tokyo University of Science have discovered the "optimal composition" for a magnesium secondary battery cathode, resulting in better cyclability and impressive battery capacity. The basics of the paper, published in the Journal of Electroanalytical Chemistry, are that scientists have restructured a magnesium (Mg) compound, replacing some of the vanadium (V) with manganese (Mn) and that this has resulted in a spinel structure with a "remarkably uniform composition." If you like chemistry, we recommend giving it a read, but we'll break the benefits down roughly here.

The restructuring of the compound has improved charge-discharge properties, and because magnesium has a higher energy density than lithium, it's worth pursuing as an alternative to lithium.


Lithium shortages have contributed to higher battery costs, and while lithium is the 33rd most abundant element in nature, magnesium is the eighth most abundant. In addition, much of the world's lithium mining is undertaken by China, which makes sourcing tricky, although the US government is working to change that.

Another factor is that lithium batteries are hazardous when punctured or at high temperatures, and all of these concerns mean that the world needs to look for alternatives if electric vehicles are to be sustainable.

Commonly, magnesium does not seem particularly viable as a replacement since Mg ions provide a low voltage window and unreliable cycling performance, which means that batteries made using the element do not respond well to regular charging and discharging. But the benefits of magnesium - chiefly its safety and abundance - spurred researchers on, and now they believe that it could one day replace lithium in batteries.

Tokyo University of Science

The scientists started with the Mg1.33V1.67O4 compound but modified it. After substituting some of the vanadium with manganese, the synthesized cathode materials (with a base formula represented as Mg1.33V1.67-xMnxO4, where x goes from 0.1-0.4 depending on which new compound it is) offered high theoretical capacity, but more work was required.

Using X-ray diffraction and absorption, as well as transmission electron microscopy, scientists evaluated the composition, crystal structure, electron distribution, and particle morphologies of the compounds. This showed that the new compounds have an unusually uniform composition, which was fascinating.

Researchers then conducted various electrochemical measurements to evaluate the battery performance with different electrolytes before testing the cathodes' resulting charge/discharge properties at various temperatures, which we know can affect the performance of electric vehicles significantly.

The scientists noted a high discharge capacity for these new cathode materials, particularly for Mg1.33V1.57Mn0.1O4, noting that the discharge capacity varied depending on how many charge-discharge cycles it underwent.

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Vice President and Professor Yasushi Idemoto, who led the research team from the Tokyo University of Science, explains: "It appears that the particularly stable crystal structure along with a large amount of charge compensation by vanadium leads to the superior charge-discharge properties we observed," adding that his team's results "indicate that Mg1.33V1.57Mn0.1O4 could be a good candidate cathode material for magnesium rechargeable batteries."

In a nutshell, this particular new compound could prove to be a safer, more affordable, and more efficient alternative to lithium, but don't break out the champagne just yet. Professor Idemoto says that more research and development are required, although he is hopeful that "magnesium batteries could surpass lithium-ion batteries thanks to the former's higher energy density."

Scientists have considered numerous alternatives to the industry standard, including seaweed and seafood waste, but will future electric cars ever make use of these innovative solutions, or will the Tesla Model 3 of the future and its kin continue to rely on hazardous lithium?

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