MATERIALS FOR NEXT GENERATION ALKALINE ELECTROLYZER
The aim of the NEXTAEC is development of next generation alkaline electrolyzer with a performance comparable to a good PEM electrolyzer or better without the use of noble metals. In brief, the PEM electrolyzer can operate at high current densities (several amperes pr. cm2) due to the low internal resitstance of a thin acidic ion conducting membrane (an ion-exchange membrane). The main drawback is that the acidic system demands noble metal catalysts on both electrodes and expensive noble metal coatings on the bipolar plates and electrode backing. The alkaline electrolyzer, does not rely on noble metals for neither catalysts nor bipolar plates, but it suffers from higher internal resistance because it does not have a thin ion conducting membrane. Despite many years of research, no research groups or companies have been able to develop a satisfactory ion-exchange membrane for the alkaline system. All attempts suffer from sigificantly lower conductivity and poor stability. The alkaline electrolyzer have so far been left with thick porous diaphragms with a significantly higher area-specific resistance, which practically limits the current density to a fraction of an ampere pr. cm2. In the proposed project, an alkaline electroyzer will be developed around a new membrane concept. The membrane is an ion-solvating membrane. It is a polymer, which dissolves the electrolyte of the electrolyzer (aqueous potasium hydroxide). Like an ion-exchange membrane it is nonporous and it can therefore, in contrast to a porous diaphragm, be as thin as an ion exchange membrane. The absense of noble metals makes it possible to roll out the technology in the multi GW scale that is needed in the green transition away from the dependence fossil fuels.