So osmosis, as I understand it, is the balancing of some substance on both sides of an opening. Like, if there is and abundance of salt on one side of the opening but a lesser amount on the other side, the salt will end up in an even amount in both chambers. Less in the chamber that had more, and more in the chamber that had less.
I understand what you are talking about in your post. Current goes from negative to positive, and the greater the difference in the positive negative gap the greater the power.
And I get that ions have a charge, but you said that the lattice was neutral, so I didn't understand.