Researchers have developed a water-based battery to store solar and wind energy

Re:Researchers have developed a water-based battery to store... by hedora on Sunday May 06, 2018 @10:32PM (#17009991)

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 electricity directly, so the chemistry can be much more stable.

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Re:Researchers have developed a water-based battery to store... by fernly on Monday May 07, 2018 @10:48AM (#17013130)

> ...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+ + 2H2O ↔ MnO2 + 2H+ + H2

Let me try that with _sub_ and ^sup^, does HN support that?

    Mn2^+^ + 2H_2_O ↔ MnO_2_ + 2H^+^ + H_2_

Anyway, that double-ended arrow says that you can read it from right to left, i.e. evolved H_2_ gets back into (or stays in?) the solution to react with the O_2_ from the magnesium oxide to make water. Quote,

> During discharge of the battery, the uniform layer of as-deposited MnO2 on the cathode is dissolved back to soluble Mn2+ electrolyte and H2 is oxidized on the anode.

So, I guess it stays in solution...?

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Re:Researchers have developed a water-based battery to store... by jwilk on Monday May 07, 2018 @11:50AM (#17013698)

HN formatting capabilities are not great, but you can use Unicode sub-/superscripts:

Mn₂⁺ + 2H₂O ⇌ MnO₂ + 2H⁺ + H₂

(Shameless plug: I generated the above with https://github.com/jwilk/chemiscripts .)

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