Hmm. Thinking along those lines . . .
Let us suppose for a moment that the cage is made of an alloy -- small amounts of kryptonite blended with lead (and perhaps some magnetic metal -- lead isn't particularly). If an electric current were run through it, which would magnetize it . . .
*ponders* Well. It's been far too long since I read up on electricity and magnetism for me to make really good predictions. But if the kryptonite were bonded somehow to the magnetic metal. And the electric/magnetic field pushed those bits to the surface.
*sigh* Well. I think this goes back to the fact that the science on L&C was pretty awful.
