BTW, they've had batteries like this for a looooooooong time. I've got some surplus radiosondes that come with that type battery. The battery comes sealed in a can. You open it, soak it in water, and voila, instant voltage. No shelf-life worries, just soak and go.
Most car batteries are somewhat similar, i.e., shipped dry, but charged. Dump in the battery acid, and there you are, a charged battery ready to go.
I'm a bit cynical about the perennial "battery breakthrough" announcements. The closest we've come to any kind of serious "breakthrough" is the Lithium Ion battery, which has the slight disadvantage of having a particularly nasty failure mode (turns into a firebomb when overcharged, short-circuited, or, "for no particular reason"), which, in addition to causing major damage due to explosion and fire, has a really nasty electrolyte (some kind of fluoride which I believe can burn right to the bone when it touches skin).
Other than that, we're looking at the incremental increase in Nickel Metal-Hydride batteries, which have come quite a way, and now have some fairly impressive MAH ratings. Unfortunately, it's hard to get them in other than AA and AAA sizes, and, even with their impressive capacity, they are NOT the be-all and end-all that they were heralded as being when first announced.
In particular, they still have some serious drawbacks compared to the humble Nickel-Cadmium battery, which is being phased out due to it containing the Evil Chemical (Cadmium). This PC nonsense is insane. NiCADs are EVIL, and must be REMOVED! from the market, but, LION cells, which have caused LOTS of real damage (and IMO it's only a question of time before one of 'em brings down an airliner), are sold hand over fist, with nary a concern for safety.
The Evil NiCAD battery, while lacking an MAH rating as high as a NiMH battery (although they too have better milliamp-hour ratings than they used to have) has one major benefit over the NiMH -- it can keep its charge a LOT better. NiMH batteries will self-discharge very rapidly -- something like ten percent a day. You can't charge 'em and stick 'em on the shelf. You need to charge them right before you use them, if you want to get that dramatic MAH capacity on the label.
The other putative benefit over NiCD was the supposed lack of "memory effect." This I find particularly cynical marketeering, because not only do newer NiCDs have MUCH less "memory" issues, but, NiMH cells seem to be as bad or worse than the older NiCDs ever were -- and, it seems to me (battery pig that I am :) that in general, they aren't good for nearly as many charge/discharge cycles (compared to the humble NiCD battery).
While I'm griping... :) Is anyone else old enough to remember when Mallory came out with their Duracell, the first Alkaline battery, which really was a dramatic improvement over the classic carbon-zinc "drycell"?
One of the selling points, included in the advertising, was the fact that -- in addition to lasting longer on the shelf, and having much greater output -- they could be recharged?
I bought a set of 'em, and kept on using 'em, and using 'em, and using 'em... When they'd die, I'd recharge 'em, and be good to go, just like having a fresh set.
After a while, they started putting "do not recharge" notices on the label. (At this point, I'm talking about ALL alkalines, not just the duracells.) Gee, go figure. Telling people to throw them away and buy new ones, instead of recharging the old ones over and over? Now why would they say that? :)
A while later, there was a change in the chemistry. Seemed to coincide with the "mercury-free!" nonsense on the labels.
Finally, a real change! Now, if you charge them, they will leak vile goop all over your charger.
Progress!
Feh.