Quote Originally Posted by Maximum77 View Post
What kind of battery would an advanced sci-fi world use, that has basis in real science (something we only speculate about today). When I say battery, I mean things that power devices not laser gun arrays. We currently use lithium-ion batteries. Basically, what would be the next upgrade after that?
I suspect the answer of the "end tech power supply for SF" is always antimatter.
https://www.xkcd.com/1162/ And the graphs would look similar with "uranium, plutonium, americanium, anti-matter".


The problem with the question is that "battery" has a different meaning to those who design them and design things that use them and consumers.

To a consumer, a battery is a device that supplies power by itself. When they are empty they are either thrown away or recharged.

To an engineer (or chemist), a battery is a device that produces electricity via chemical reactions. This is pretty important as there are other ways to store/generate power. Fuel cells are basically batteries with the chemicals separated and in tanks waiting to be reacted in the fuel cell. Flow batteries are similar to fuel cells, except can be reversed to charge the battery (don't expect to use hydrogen and oxygen, the reverse is terribly inefficient). If it must be a (fairly large) chemical battery, a flow battery is ideal (although the benefit is that it is mostly the reactants and little amounts of electrodes/"battery bits". This likely means less power and such things are expensive/limited. Don't be surprised if things go back to scaled up lithium-style batteries (only with zinc electrodes) for maximum power).

Capacitors have increased storage by ridiculous amounts (I was told that a farad was too large a unit to use "a one farad capacitor would be bigger than this desk", 20 years later a place was giving away samples of 8 farad capacitors about the size of a d20. These also have the advantage that they can be charged/discharged nearly instantly, although I suspect there are physical limits that won't let them store as much as a modern battery.

RTGs [radioactive thermal generators] are a pretty good look at a "SF battery". NASA uses them for missions beyond Mars (and for at least the Curiosity rover). They are about as primitive a means of using radioactivity as possible (mostly to save weight): more complex systems may be designed to alter the density of the radioactivity to "smooth out" emissions over the years (current systems decay with the halflife of their isotopes: after 40 years of operation the Voyager power supplies should be roughly at half strength). Note that RTGs simply can't emit power any faster than they are designed for: for all their massive capacity, there isn't the danger of sudden explosions (unlike lithium ion, and moreso capacitors and antimatter).

There are a lot of ways to imagine an antimatter battery, presumably similar to an RTG or perhaps like a gasoline engine. But never forget that if the containment fails, all the energy is discharged at once.

While fuel cell based "batteries" may have the proper SF flavor, I suspect that they have similar efficiency limits as current fossil fuel engines/generators. Namely, if you used the chemistry of a fuel cell more efficiently than a heat/carnot engine then Carnot could show you how to produce a perpetual motion machine. It might be easier to get close to the limit with chemistry, but don't count out heat engines (and expect things like a sterling engine to be used with real RTGs, never mind what might be used with antimatter).