shows a single cell of taper-end structure used in the experiment. The cell can be manufactured with materials resistant to corrosion by alkaline solution. PTFE is excellently stable in alkaline condition but too soft to endure pressure. Therefore, the cell was manufactured with an engineering plastic (monomer cast Nylon) which is hard enough to maintain the shape and is stable to aqueous alkali even though rapidly degrades in aqueous acids. The anode current collector was made of perforated stainless steel sheet, and the cathode current collector was made of a nickel mesh sheet. A Viton fluoroelastomer (DuPont) gasket was used for sealing the cell.