Its a battery because its being recharged and run down, rather than continuously producing power.
Its a complicated way of getting very small amounts of stored power, but it is stored power.
"This discovery should bring us closer to solving global energy problems." is the bit in the abstract thats pure hype. Its not just a thermopile, but its not going to beat them, and thermopiles aren't exactly world saving themselves.
Richard
Is this then the equivalent of an intermittently heated or cooled piezo device or thermocouple that could theoretically feed into a "Joule Thief", and eventually charge a conventional cell?
Does the amperage or voltage vary with the temperature delta so that it could be used as a thermometer, or to drive a throttle capable of adjusting the delta temperature of an attached heater or cooler?
I still can't see the "battery" designation as I visualize this as generating a very small amount of electricity from a thermal delta, then after a short period overloading itself so that it needs to be briefly open circuited before it can continue.
I've no doubt that you (and the gents that invented it:>) are correct in their designation, but confess that I don't understand the nomenclature.
I am totally in agreement that this is no game changer. An interesting exercise possibly, but I see no advantage over mass produced sub-assemblies that have been available for many decades.
Terry
Terry