Tubular PEM electrolysis cells with a 3D-printed oxygen electrode and ALD catalyst coating

Abstract

Polymer electrolyte membrane electrolysis (PEMEL) is a technology with a major role in linking the hydrogen production to renewable energy resources with a volatile behaviour such as wind and solar. High amounts of precious metals and a labour intensive production also make it a cost intensive technology. A tubular cell design has the potential to reduce production costs by co-extrusion of cells which feature a reduced sealing length. For the inner half cell, additive manufacturing (AM) of titanium offers a high degree of freedom for the electrode design to reach a high electric conductivity and active surface area. In combination with atomic layer deposition (ALD) of iridium catalyst a porous transport electrode (PTE) can be fabricated. Using planar test cell results and model based PTE design, this study demonstrates the feasibility of a tubular PEMEL cell consisting of an additively manufactured, iridium coated anode PTE in the inner half cell, an extruded membrane and a platinum coated graphite felt cathode PTE in the outer half cell. The outer titanium current collector can be replaced by an extruded graphite polymer compound current collector to reduce the amount of titanium without performance losses. The cell is operated at 60 °C in 1 mol L−1 sulphuric acid and experimentally characterized by polarization curves and electrochemical impedance spectroscopy (EIS). At 2.0 V cell potential a current density of ≈450mAcm−2 was reached corresponding to an iridium mass specific current density >1500Ag−1 which is significant larger than literature values.