# What MnO2 and graphite do I need for making a dry cell battery?

I'm playing around with making my own dry-cell battery and I want to make sure I understand the pieces before diving into it.

My plan is to make it like a layer cake: zinc sheet, paste of electrolyte, layer of $\ce{MnO2}$ powder, graphite sheet, and a metal sheet with a wire connected to it.

What I'd like to understand better is:

1. Could I replace the zinc sheet with Zn powder? (Also this is interesting, but I don't understand what's meant by a Zn sponge, is it Zn powder with $\ce{Ca(OH)2}$?)
2. How pure/fine does the $\ce{MnO2}$ powder need to be? Potters used $\ce{MnO2}$ to color clay, is this the same stuff as what's in batteries? I tried emailing a few places but they didn't know the chemical properties and I'm not confident enough to go for it without double checking first :/
3. Could I use carbon filters or even crushed charcoal or does the electrode need to be a solid sheet of graphite? I think carbon filters and graphite sheets have the same chemical properties, but I'm not sure.