One promising way to store and distribute large amounts of renewable energy is water electrolysis, coupled with transport of hydrogen in the gas grid and storage in tanks and caverns. The intermittent availability of renewal energy makes it difficult to integrate it with established alkaline water electrolysis technology. Proton exchange membrane (PEM) water electrolysis is promising, but limited by the necessity to use expensive platinum and iridium catalysts. The expected solution is anion exchange membrane (AEM) water electrolysis, which combines the use of cheap and abundant catalyst materials with the advantages of PEM water electrolysis, namely a low foot print, large operational capacity, and fast response to changing operating conditions. The key component for AEM water electrolysis is a cheap, stable, gas tight and highly hydroxide conductive polymeric AEM. Here we present target values and technical requirements for AEMs, discuss the chemical structures involved and the related degradation pathways, and give an overview over the most prominent and promising commercial AEMs (Fumatech Fumasep® FAA3, Tokuyama A201, Ionomr Aemion™, Dioxide materials Sustainion®, and membranes commercialized by Orion Polymer), and review their properties and performances of water electrolyzers using these membranes.

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A stable, non-platinum-catalyst-coated anion-exchange membrane with a promising performance for alkaline water electrolysis as an energy conversion technology is prepared and tested. Hot plate spraying technique is used to deposit electrodes on surface of the anion selective polymer electrolyte membrane in the thicknesses of 35 and 120 m corresponding to the catalyst load of 2.5 and 10 mg cm -2 . The platinum free catalysts based on NiCo2O4 for anode and NiFe2O4 for cathode were used together with anion selective polymer binder in the catalyst/binder ratio equal to 9:1. The performance of the prepared membrane electrode assembly is verified under the conditions of the alkaline water electrolysis using different concentrations of the liquid electrolyte ranging from 1 to 15 wt.% KOH. The electrolyser performance is compared to the cell utilising the catalyst coated Ni foam as electrodes. The prepared membrane-electrode assembly stability at a current load of 250 mA cm -2 is verified by an electrolysis test lasting for 72 hours. Results of the experiments provided indicate a possibility of the significant catalyst loading reduction when compared to the catalyst coated electrode approach.

In this study, the chemical stability of three types of the anion-exchange functional groups in an alkaline environment was tested. The following groups were selected for the test: trimethylbenzylammonium, methyl pyridinium, and tributhylbenzylphosphonium. A KOH solution with various concentrations and temperatures was used as the environment. The trimethylbenzylammonium group showed the highest stability of the materials tested under conditions relevant to water electrolysis. In the next step, four types of polymeric binders, including ethyleneco-methacrylic acid, linear polyethylene, linear polyethylene blended with poly(ethylene-co-vinylalcohol), and low-density polyethylene, were selected to determine their impact on the resulting electrochemical properties of a heterogeneous membrane. This study reveals the morphology of the membrane, ion-exchange capacity, ionic conductivity, and performance in alkaline water electrolysis conducted on a laboratory scale. The material showing the most promising properties was selected for further optimization and testing.