The result isn't exactly surprising: sure, this kind of “battery” has an enormous energy density but you need thousands of years to actually harvest the energy. Even assuming that no energy is converted to heat (rather unlikely), the output of a 1 kg battery will be below 3 watt.
That should be barely enough to power a smartphone. So the use cases mentioned in the articles are complete bullshit: even an electric bike would need at least 100 kg in battery. Electric cars? Just forget it…
Ouch, typo in the image – 1.81 * 10^19, not 1.81 * 10^20. Also, it's 2.9 J/s, not 29. The end result is correct, I forgot to correct a mistake for intermediate steps. ☹️
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