P.A. Kohl, W.E. Mustain, B. Zulevi
Georgia Institute of Technology,
Keywords: electrolyzer, alkaline, high conductivity membranes, ionomers, catalysts
Summary:Low-temperature water electrolysis using anion conductive polymer electrolytes has several potential advantages over acid-based polymer electrolyzers. Anion exchange membrane electrolyzers allow for the use of platinum group metal free electrocatalysts and low-cost component materials (i.e., membranes and cell components) due to its less corrosive alkaline environment while also enabling electrochemical hydrogen compression. A family of hydroxide-conducting, high-conductivity polymers with excellent durability based on poly(norbornene) has been develop. The polymers have been used to make reinforced, hydroxide conducting membranes for electrolyzers and fuel cells. The same polymer family has been used to make self-adhesive ionomers for electrode fabrication. In particular, the adhesion and connectivity of high surface area, particulate catalysts to the porous transport layer is critically important to the long-term cell lifetime. In this study, self-adherent, hydroxide conducting ionomers have been combined with high-conductivity, reinforced membranes and new oxygen and hydrogen evolving catalysts in alkaline electrolyzers. The electrode ionomers used in electrolysis electrodes, especially at the oxygen gas producing anode, must provide adhesion between the catalyst particles, porous transport layer and solid polymer membrane. Simple mixtures of ionomer and catalyst can suffer from poor catalyst adhesion because only physical adhesion is used to bind the components together. Electrolyzer results show stable voltage performance over long periods of time.