Using a calcium metal anode in aqueous solution? In school, I am doing an electrochemistry lab in which I need to create a galvanic cell battery with the highest voltage possible using two beakers, a salt bridge, and electrodes.

To maximize the voltage, I have decided to use calcium metal for the oxidation half-reaction and a sodium persulfate solution for the reduction half-reaction. I understand that for the reduction reaction in the cathode, I would merely dissolve the persulfate in water. However, calcium metal reacts with water, so how would I go about connecting the calcium to the salt bridge (which is a requirement in the lab)?

The salt bridge has an aqueous salt and my chemistry teacher said that the redox reaction that would result from letting the calcium touch the water would prevent it from being effective in the battery. Also, my class vaguely touched on the Nernst equation, but are there any other revisions I can make to the battery to increase the voltage, either by adding $\ce{OH-}$, $\ce{H+}$, or increasing/decreasing concentration of the persulfate solution?
Basically, the reaction of calcium with water short-circuits your battery; the electrons you wanted to go through the external circuit end up going directly into the electrolyte instead.

Magnesium will work better for your anode; it reacts little or none with water when cold and it's anodic potential still packs a pretty good punch.