Earlier quoted context omitted.
In the modern sense of the word, this is not a battery. It is a device that cracks water into hydrogen, which can then be fed into a fuel cell. Presumably, it consumes distilled water, which is why it is targeting utility scale storage and not home installations. The work sounds interesting, but the article is painfully written. Lead acid batteries produce hydrogen too. I think the insight is that this can’t produce…
> ...not a battery. The paper, linked below (thanks xelxebar) would beg to differ, it says > we report a rechargeable manganese–hydrogen battery, where the cathode is cycled between soluble Mn2+ and solid MnO2 with a two-electron reaction, and the anode is cycled between H2 gas and H2O through well-known catalytic reactions of hydrogen evolution and oxidation. They give an equation for the cell operation as, Mn2+ + 2…
Mn₂⁺ + 2H₂O ⇌ MnO₂ + 2H⁺ + H₂
(Shameless plug: I generated the above with https://github.com/jwilk/chemiscripts .)