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It was claimed in this article in 2019 that a nano-battery using water splitting technology is developed. It is described as:

The battery gains its charge by interacting with water molecules present in the surrounding air. When a water molecule comes in contact with the reactive, outer metal section of the battery, it is split into its constituent parts — one molecule of oxygen and two of hydrogen. The hydrogen molecules become trapped inside the battery and can be stored until they are ready to be used. In this state, the battery is "charged." To release the charge, the reaction reverses. The hydrogen molecules move back through the reactive metal section of the battery and combine with oxygen in the surrounding air.

There are hardy any details on the article regarding the mechanism of this reaction and what the material of “the reactive, outer metal section” is. And I have found no paper published with this research. The description makes this battery sounds like a perpetual machine: splitting waters from environment into oxygen and hydrogen, and make hydrogen and oxygen react to create electricity. What would be a good explanation of the mechanisms that makes this possible? I guess there must be other things going on to keep this described mechanism going, which limits the life of this battery.

It is also claimed that:

The batteries have also demonstrated a power density that is two orders of magnitude greater than most currently used batteries.

But no experimental data is provided (since there’s no paper found).

Is this result somehow exaggerated? Since no application of this battery has been recorded. Also what is the water-splitting mechanism? If it is really this amazing I believe it can be applied inside human bodies to split water and power devices as well, since both nanoscale and larger scale such batteries can be made. But is such technology really practical and applicable now?

RLR
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    The "two orders of magnitude greater than most currently used batteries" isn't 2x but 100x: an extraordinary claim! It's a project by researchers who admit "none of us are battery people." But they seem to have overlooked that in very dry air, *it won't work*. – Weather Vane Nov 10 '21 at 16:39
  • As @weathervane says there are some *serious* red flags in the blurb there. – Shadur Nov 10 '21 at 17:13
  • That article is pretty light on details, which is a bit surprising coming from MIT. This question (or an accompanying question for clarification) might be better on [physics.se]. – Reinstate Monica -- notmaynard Nov 10 '21 at 17:24
  • @WeatherVane that’s why I wonder if it would work inside human body for implants. But it doesn’t seem to develop any further on this direction of medical use, or any other use in chips as well. – RLR Nov 10 '21 at 19:56
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    It doesn't actually say whether or not the reactive metal is used up as part of the process. Zinc air or aluminum air batteries seem like magic, creating electricity from fresh air, until you realise that the metal is consumed as part of the process. – Simon B Nov 10 '21 at 20:06
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    https://apps.dtic.mil/sti/pdfs/AD1098927.pdf Link to research report that describes the work in detail. – George White Nov 11 '21 at 04:33
  • @GeorgeWhite nice find! Figure 2 in that report shows a comparison of energy & power densities between various types of battery, but IMO the "**power** density that is two orders of magnitude greater than most currently used batteries" is 'optimistic'. Visually, they seem to be referring to lead-acid batteries and not lithium-ion, where the power density is only *one* order of magnitude better. And their **energy** density is *no better* than Li-on. – Weather Vane Nov 11 '21 at 13:14
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    I think treating the original article as a technical document rather than an enhanced press release was most of the skeptical problem. – George White Nov 11 '21 at 15:09
  • @GeorgeWhite thanks for the reference! – RLR Nov 11 '21 at 16:51
  • @WeatherVane Nice point. Another thing is that I thought the battery can be self-charged with water, but according to the diagram it seems that we still need to connect it to a power source to make it able to split water. – RLR Nov 11 '21 at 16:54
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    @RLR That would have been a violation of thermodynamics. You need energy to split water molecules. Indeed, you ned MORE energy to split them up than you'll gain joining them back again. – Rekesoft Nov 12 '21 at 09:24
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    @RLR: Let's [go to chat](https://chat.stackexchange.com/rooms/131383/discussion-on-question-by-rlr-nanoscale-hydrogen-batteries-that-use-water-splitt) about what you are investigating, and how we can improve the questions. – Oddthinking Nov 12 '21 at 13:36

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