Although the term “quantum battery” is a somewhat vague term, the cell is the one [Kieran Hymas] et al. evidence in a recent paper seems to suggest that it uses quantum effects to charge faster than would otherwise be possible, with this rate increasing faster than its volume, that is, at a superextensive rate.
The general idea behind a quantum battery is that these somehow use a quantum effect to store and release energy faster than would be possible with classical physics. First proposed in 2013, the initial thickness model shot down its theoretical quantum advantage by 2020, leading to the search for alternative models.
We have previously seen claims of a quantum advantage in batteries based on the Sachdev-Ye-Kitaev model, such as [Davide Rossini] et al., but this new paper may be the first prototype cell to show a reproducible effect.
In the cell demonstrated here, a microcavity with strong light-matter coupling is created that allows both energy storage and discharge, with the illuminated particles absorbing light super with what the researchers claim is due to these particles cooperating with a quantum mechanism. Effective scaling of the cell would therefore scale up the charge and discharge rate faster than in a conventional chemical cell.
Whether this demonstration can be replicated and expanded remains to be seen, of course. The stored energy in this experiment was very small and the storage time only very short, so for now it mainly serves as an interesting experimental result for researchers to dig through.