Electrical Theory and Battery Discharges

http://pubs.acs.org/cgi-bin/abstract.cgi/jpcbfk/1998/102/i49/abs/jp982825p.html

Some of the info you seek can be found here.

This could be, perhaps, be the battery we've been looking for.

Every time i've looked @ "super battery", i've always returned to what we referred to as Pb/A.

Just a strong caveat to thoroughly evaluate all data b4 jumping to any conclusions!

A battery is nothing more than a rubber box with plates of no particular polarity. Pour some H2SO4 cut with a small amount of water into the box and the plates become capable of becoming polarized. Flash the posts in the direction you would like the current to run and walaa you have a working battery. There is a continual battle within the rubber box in an effort to determine polarity Do not short the posts unless you would like a face full of battery.

TeamSarge

"Sarge" here is maybe a bit simplistic in 'details of construction', but absolutely 'spot on' regarding negligence in implementation!!! Excersise much diligence!!!!

I am the OP - i will register soon

Would a battery that you can "command" polarity have identicle material in both plates?

So the polarity markings on a typical battery are of the end user? I've poured H2SO4 into a dry lead-acid battery a few times, but i've never seen or heard of a battery that "chose" the opposite polarity from the markings. I thought possibly the more permeable, or reactant, of the two plates would become the positive, if we go by the theory that electrons flow from negative to positve.

Thanks for your answers and assistance.

The manufactures of lead acid batteries set the polarity by making one plate out of lead the other out of lead oxide. If you discharge the battery both plates become lead sulfate and charge with reverse polarity it will change the polarity of the battery.

"Battery" so described: Lead/ Acid. Plates= pure sponge Pb + Pb compound; cannot be exactly the same; else no differential V. Required for a real cell.

OP again - i have to post this so i can get an e-mail if somebody answers.

Thanks again.

As OZZB has said, it is possible to reverse the voltage in a battery. I've seen thousands of batteries being "reversed" (run down then reverse charged) at a military camp when I was younger. (Don't know exactly why but maybe overseas equipment being made compatible with some army expectation. Army intelligence?) Note the plates are made from the same "parent" material.

I suspect what you are seeing in your cell might be a little different. You initially had two dissimilar metals (zinc and aluminium) in a conductive solution and would see a galvanic effect.

Once the zinc is all dissolved you then have iron and aluminium electrodes in a conducting solution which has a different galvanic effect.

Maybe this accounts for your observation of the changed performance.

When using two dissimilar metals such as zinc / aluminum to make a battery, the voltage is generated via galvanic action. The metal that releases its electrons most freely become the negative and therefore the other becomes positive.

Zinc is used as anodes in many services, ships, pipe lines, etc because it most freely gives up it electrons. If the anodes are not used then the pipe line, ships hull, may become the negative field and the sacrificial component. It does not just give up electrons but the metal it self is transfered to the cathode. Works just like electroplating.

You are making a battery that relies only on a chemical reaction that is nonreversable. You cannot send the zinc back to its original source.

In a lead battery the plates have a chemical change that can be reversed by charging, and in fact the positive plate can be made negatived by completely discharging the cells and applying voltage in the reverse direction. (Do not try this - I saw a battery explode during a demonstration).

Thanks to all that replied.

There is much to ponder when you read of a liquid anode. Just how do you "harvest" it's potential without throwing off the primary action with an unintended reaction? For example a zinc/air battery: Just how does one hook leads to air? But if we go back to plates of like material this could make it possible. Eventually it has to get to a copper wire, but copper itself is reactive and can contaminate the reaction.

much to ponder indeed

Zinc/Air battery still uses an electrolyte (KOH works well) and two electrodes for conduction, one contacting the Zinc and one suspended in the electrolyte. The reactants are Zinc and Oxygen. The Oxygen is obtained through electrolyte contact with air, hence the Zinc/Air designation.

another related question:

did they not make a copper/acid battery because of the material expense compared to lead? Seems copper oxidates and sulfates similarly to lead.

Thanks again

Lead is more resistant to chemical attack from Sulfuric Acid than Copper. Copper placed in Sulfuric Acid will dissolve and form Copper Sulfate. A simple replacement reaction, no electron transfer required. If a piece of Lead is placed into a container of Sulfuric Acid, the surface of the Lead will passivate in the form of Lead Sulfate. Only a minute amount of the Lead will actually dissolve. Assuming the Lead Sulfate is not removed from the surface of the Lead for any further reaction to take place a electron transfer must take place, a Red-Ox reaction.