Lithium ion batteries have become the energy storage medium of choice for everything from cell phones to electric vehicles and large-scale support of power grids. But lithium isn’t the only lightweight metal that can be used in batteries. As a result, researchers around the world are examining other candidates for possible commercialization.
Magnesium is of particular interest. Potentially, batteries made from magnesium metal could have higher energy density, greater stability, and lower cost than today’s lithium ion cells. At least those are the predictions of scientists at the Department of Energy’s National Renewable Energy Laboratory (NREL), who have detailed in Nature Chemistry their recent results with rechargeable magnesium metal batteries.
Chunmei Ban, a scientist in NREL’s Materials Science department and a co-author of the Nature paper, stated the following in an NREL press release: “The dominant lithium ion battery technology is approaching the maximum amount of energy that can be stored per unit volume, so there is an urgent need to explore new battery chemistries that can provide more energy at lower cost.”
Magnesium has several other advantages over lithium in battery applications. Each magnesium atom releases two electrons during the battery discharge phase, compared to one electron for lithium. This gives it the potential to deliver nearly twice the electrical energy that is possible from a lithium cell. In addition, magnesium does not grow dendrites on the metal surface during the battery charging phase. The spiky dendrite crystals that grow on a lithium metal surface can cause short-circuiting of the battery. The lack of dendrite growth should make magnesium batteries easier to handle and safer. Lastly, magnesium is more common and readily available than lithium. According to the USGS, it is the eighth most abundant element and can be commercially extracted from mineral deposits or seawater.
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