toyota developing magnesium vs lithium, page-4

"Such batteries should also have a higher storage capacity than lithium-ion ones because magnesium ions have a positive charge of two, rather than one for lithium ions. A magnesium-ion battery could store more charge per gram, and that would translate into a longer driving range in a car or running time for consumer electronics. But the chemistry involved in making a magnesium-ion battery work efficiently has yet to be perfected."

Don't rely on Journos for a basic science education, those stories are full of fluff and factually incorrect. Any student of the periodic table will tell you it CANNOT get any better than Li for a battery.

The charge density of Li is 3.86Ah/g whereas for Mg it is 2.2Ah/g. Therefore, Li generates twice the electrical charge per gram when compared to Mg.