Assuming the article is correct, all they have is a device which doesn't degrade over time. It will cycle and cycle for "400 years" by picking up and releasing charge. Great. So can a really well made capacitor. But what is the capacity of the battery, and how much current can it deliver?
Capacitor-style storage semiconductors for memory, solid stage storage and microprocessors can also cycle billions of times without showing any sign of degradation. Sure, they store a minuscule amount of charge... only enough to hold a "0" or "1" to be read later. But that doesn't mean they can provide much power.
So the question remains, this battery can cycle... but what kind of capacity can it store? Assuming it is good enough, then the question is can they ramp up production to levels that bring costs down and will the characteristics be useful for most devices.