Steam - 2-5-2014 at 05:47
I was thinking and I came up with this idea and I was wondering if it would work.
I know the Nernst equation is used to calculate cell potential outside of slandered conditions. What I was thinking was to use it to make a battery
have an high initial potential by having the metal salt precipitate at the anode. Perhaps a heavy metal chloride as an anode? By doing this the
concentration of the salt will always stay extremely low (approx [0]). Meanwhile at the cathode where the metal salt comes out of solution, I would
have a solution that is over saturated. Ie, having undisolved salts at the bottom of the cell. With stirring this would keep the concentration of the
salt at its saturation point.
Would this cause the voltage of the cell to be at it "maximum" potential for as long as the extra salt in the cathode isn't used up?
Metacelsus - 2-5-2014 at 13:09
You might be better off using something like aluminum or zinc and a phosphate instead of a heavy metal and a chloride.
Steam - 2-5-2014 at 19:49
Good point, Got to keep safety in mind! 
But is the idea there? Would this make a big difference within the battery?
Metacelsus - 3-5-2014 at 05:06
It's not just safety; more active metals will generate more voltage.
I think that it would have an effect; the voltage would not drop until the precipitating salt is used up. However, you might run into the problem of
your anode being encrusted in precipitate.
Illusionist - 3-5-2014 at 05:15
You could add something to shake the anode periodically if the precipitate does not adhere easily to it.
You could also build the anode of two sliding perforated metal sheets and have them moving against each other to dislodge the precipitate. (like the
moving and stationary part in a hair trimmer)
Steam - 3-5-2014 at 10:27
Sort of ruins the point of the battery if you have to shake it in order for it to work!
It is a school contest though so I can just shake it off before my teacher tests the voltage. I think I am going to use Silver and Aluminium. That
silver salt that has been laying around the lab is begging to be used!
[Edited on 3-5-2014 by Steam]
Metacelsus - 3-5-2014 at 10:40
Is the point of the contest to have the most voltage? There was a similar thread around here . . .
http://www.sciencemadness.org/talk/viewthread.php?tid=23879
Galinstan - 3-5-2014 at 12:44
the idea of using a very insolble salt in a cell is the reason the caromel cell produces such a stable voltage and is used as an standard electrode,
so yes using this method with another insoluble salts will make the voltage of the cell remain fairly constant at S.T.P
Steam - 3-5-2014 at 20:10
Yes, so it is the highest stable voltage, but the rule is that you can only use one cell. I actually have some Lithium metal in my lab at home. I am
going to do some quick math tomorrow to see If just a normal Lithium-silver cell would be better.
Would have to deal with running it on non-aqueous inert conditions but it might be better!
Will also have to ask the teacher if I can use my own chemicals... hmmmm.
[Edited on 4-5-2014 by Steam]
Illusionist - 4-5-2014 at 09:32
Maybe a small piezoelectric element could induce enough vibration to get rid of the precipitate accumulation on the electrode without draining too
much voltage.
If you could have Hydrogen generated at the anode, maybe it would prevent buildup of the precipitate.