It does not convert metals between metallic and ionized forms, and does not take sulfur into or out of the complex, so your can't just traverse the periodic table and get there. On practice battery research is about ballacing a much larger set of features, like cycle efficiency and durability, so the obvious metal+halogen solution almost always loses.
Yes. So many that a site of 1, 2, and 5 years ago in battery announcements would be useful. They don't have a battery installation. They have a press release that they signed a contract to do a battery installation. There's a difference.
The tech is still secret, other than being "aqueous air."
Right.
There's a web site: https://formenergy.com/ Stock photos and an onboarding funnel.
Did anybody ever get the "flow battery" thing to work well enough to be useful? That at least solves the capacity problem; you're limited only by tank capacity.
There are a few flow batteries about using the vanadium-redox chemistry: https://www.sciencedirect.com/topics/engineering/vanadium-re... - and that web page lists operating installations.
From the other comments it appears this might be sulfur: https://www.sciencedirect.com/science/article/pii/S254243511...
The reasoning is sound; for every element on the periodic table, you can assign a dollar cost, and an ionization energy. From the ionization energy you can work out the electrode voltage of a particular chemistry, and therefore the terminal voltage of the battery, and therefore how much energy is liberated from each electron exchange. Divide "watts per atom" by "dollars per atom" and you have your bulk storage cost. Throw out all the substances that are annoying to store (sorry, hydrogen), or don't behave nicely in an ionic liquid at room temperature.
That gives you the smattering of elements that have been tried for batteries. Lithium wins on weight because it's at the top left (sorry again, hydrogen), and the collection of "post-transition metals". Zinc, Cadmium, Mercury, Lead: all popular. Aluminium-air batteries exist but are expensive.
Sulphur seems all on its on in the "reactive nonmetals" bucket. I'm guessing it's being considered due to availability especially in sulphuric acid form.