I've been playing around with some different materials that will allow current to pass through but not gas bubbles. I have not yet identified a cheap and readily available material. Another challenge is trying to find a suitable separator material that will not turn into a gas producing surface.
I'm currently focusing on Cellophane, Polymers, Mesh Screens and others.
Simple Saran Wrap allowed electrical current to pass through for a short time but eventually stopped transmitting current. I'm pretty sure it was because of a buildup of gasses on the surface of the cellophane.
I'm trying to design a dry cell with two plates. The Dry Cell will have two chambers separated by a conductive membrane. The membrane will separate the negative and positive plates but allow the large plate surfaces to be very close together.