I'm creating a voltaic cell project for my high school chemistry students. This is a design challenge for them to use electronegativity differences to produce enough voltage and current to power a small DIY motor and fan. So far, I have been able to generate about 1.7V but only 0.4mA using lots of spirals of Mg ribbon along with a Cu electrode using porous cups (and not a salt bridge). I've increased the concentration of Copper nitrate. What methods might increase the current? We're have enough voltage to run 1.5V DIY motors but they won't run due to lack of current.

We're doing this: http://static.nsta.org/files/tst1409_30.pdf


1 Answer 1

  1. Increase the area of the electrodes (e.g more ribbon).

  2. Decrease the resistance of the electrolyte (e.g. reduce the spacing between electrodes, increase concentration of salts).

  3. Reduce polarization of electrodes (bubbles on surface, etc.). Scrape or lightly sandpaper the electrodes and test immediately after immersion, before bubbles form.

  • $\begingroup$ Thank you for the ideas. I put quite a lot of Mg ribbon spirals. I'll try all of these in combination. A friend said maybe increasing the contact of the electrode and the wires might help. Would that help? $\endgroup$
    – JMcVay
    Apr 22, 2017 at 20:20
  • $\begingroup$ It could if the electrode is quite dirty or oxidized, but normally the resistance of the electrolyte is far greater than contact resistance of wire and electrode. $\endgroup$ Apr 23, 2017 at 1:11
  • $\begingroup$ That helps. These are new electrodes so shouldn't be a problem. I'll keep working on it. thanks $\endgroup$
    – JMcVay
    Apr 24, 2017 at 23:40

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