Separator development for alkaline water electrolysis
- Persons involved: Cloë Berkien (PhD Candidate), Rob Lammertink (promotor), Nieck Benes (co-promotor), Wiebe de Vos (co-promotor)
- Duration: 2025-2029
- Funding: SFI-NWO NGF Groenvermogen ubnder consortium HyPRO
Introduction
Water can be split into hydrogen and oxygen gas upon charging an electrochemical cell, known as a water electrolyzer. This generated green hydrogen is unlike hydrogen produced from fossil fuels, as its production does not emit greenhouse gases when coupled to a renewable energy source. Hydrogen is of significant relevance for many chemical industries, and in addition, can serve as an energy carrier by storing electrical energy in the form of chemical energy, which can be converted back into electrical energy in a fuel cell when required. This is especially valuable given the continuously increasing contribution of renewable energy sources, such as wind and solar, which are weather dependent and therefore fluctuate accordingly. Storing surplus energy, for instance in green hydrogen, enables a more constant energy supply by bridging periods of reduced renewable energy generation.
There are various technologies that enable the generation of hydrogen through water electrolysis, of which alkaline water electrolysis is the most mature due to its relatively cheaper and more robust materials. In this technology, the electrolyte separating the two electrodes is of a highly alkaline pH to enhance conductivity and the redox reactions at the electrodes. A porous separator is placed between the two electrodes to separate the produced gases, whilst allowing electrolyte infiltration for ionic transport. However, despite its relative maturity, the operation of alkaline water electrolysis is still limited by high resistances within the electrolyzer cell, with transport limitations mostly occurring in the separator. In addition, the produced gases are not always sufficiently separated to maintain safe and continuous operation conditions.
Key words
Green hydrogen, alkaline water electrolysis, separator development, polymeric materials, ionic transport, gas crossover
Technological challenges
The separator’s performance is dependent on a trade-off between conductivity and gas crossover. Improving one often worsens the other. Therefore, this project focuses on finding the right chemical composition and manufacturing method to manipulate transport processes in the electrolyzer, in turn allowing for optimal performance.
Research goal
The goal is to fabricate a sustainable separator that allows for improved conductivity, limits the mixing of hydrogen and oxygen, and remains chemically and physically stable in highly alkaline and heated environments. In this way, the separator can contribute to optimal operation of the electrolyzer, thereby supporting the goal of the consortium HyPRO: maximizing the efficiency of green hydrogen production.
