Why not calcium batteries?

Indeed, your regular automotive "lead-acid battery" is more properly called a "lead-calcium battery", although the calcium is a very small part (way less than a percent) in the alloy.

Tim.

Potassium is plentiful and cheap (well, not the metal, but there are other ways to deal with that.. I'm sure Li-ion technology can be applied, though the clathrate structure will probably have to be a bit bigger to squeeze in those pudgy potassium ions), and barium has the highest reduction potential of the alkaline-earths.

Mg and Al are *somewhat* stable in water, but that depends on your definition. Mg will deteriorate, while Al will remain passivated in certain solutions (boric acid or dichromate), while others corrode it (I personally have made alumina hydrate by dropping metal in a container with a little lye in solution; yum, I can just *taste* the entropy increase!).

But it also has less voltage, and possibly less energy density or resistance.

Maybe somebody will realize a fuel cell using fluorine gas and lithium metal (~= 6V).

Tim

-- Deep Fryer: a very philosophical monk. Website:

Unfortunately, you can't simply pick two things far apart on the electrochemical series, and make a battery. Well, you can... But. You probably won't end up with something that can be recharged.

You've got to end up with something that both electrodes will plate out in smooth layers (or smoothly onto structures) on the application of current in a shared electrolyte. Something that doesn't suffer too badly from dendrites puncturing the seperators between plates, that's mechanically robust enough to be formed into a cell, that won't go bang if you puncture it, that doesn't contain the latest toxin of concern, that will last for hundreds or thousands of cycles without degrading, with low internal resistance, high energy density, high power density, and less expensive than competing cells.

Not to mention that you're going to have to go some to pick a combination that nobody has thought of.

Cringe!

I know - in jest, but ...

Regards Ian

Yeah, there ya go! All those yuppies pulling up to the filling station in their SUVs to fill up with liquid fluorine and blocks of raw lithium.

Well, at least they won't need "no smoking" signs... ;-)

Cheers! Rich