Another could-be-a-better-battery-in-20yrs article .. wake me in 20yrs

The future is EV's and nothing else.

Perhaps in 20 years Magnesium becomes a dominant part of batteries for EVs. But, let's not forget that Lithium based batteries also will keep improving and we are already very soon hitting a point where EVs are becoming highly attractive as alternative to gas powered cars with cars like GM Bolt and Tesla Model 3 entering mainstream pricing with usable range.
Perhaps the truth is that Toyota is riding on a wrong horse with a name called "Hydrogen" that sounds cool on paper but doesn't deliver in terms of a number of issues including end-to-end energy efficiency, ability to provide the comfort of home charging, complexity of rolling out a fueling network, making hydrogen cars perform as good as EVs (especially horsepower) and so on.

LiIOn batteries are notorious for burning things up. Magnesium can burn.....and once it does start burning it's a major PITA to get put out. So we'll see if they can make these work....and more importantly if they can be made to work safely.

If this works as described, Rana deserves a Nobel because she will have brought an inexpensive very powerful battery to the world.

Good comments so far. Mag is already in many lithium batteries. Like the Volt pack I bought for my next EV. There will be many battery types in 20yrs that will blow away present ones. In just 10yrs lithium will cost only $60/kwhr And only weigh 8lbs or so just following present trends. So any replacements need to be really good.

A Hydrogen Fueled cell With Magnesium. What could go wrong when it's on fire?

20 years???
Hogwash. They have nothing -- nothing at all. They think it'll be more dense. I can think that batteries are powered by candy canes and unicorn farts. But that doesn't make it so.
If they had something that worked in the lab, then in 5 years they could be making money hand over fist with a better battery. The fact that they don't even have that, means this story is about nothing.
We have a term for this sort of thing. Vaporware.

In 20 years.....so in essence nothing. Vaporware. I guess Toyota is realizing that their hydrogen car is an inefficient dead-end so time to drum up some publicity.

Your drawing has the plus / minus signs labelling the charge potential of the anode and cathode reversed, but the positive electrons are flowing in the correct direction from anode to cathode.