Temperature and Alkali Stable Polymer Electrolytes for Hydrogen and Carbon Dioxide Alkaline Electrolysers

The project aims to develop innovative polymer electrolyte based electrolysers with lower life cycle costs (achieved by enhanced efficiency) utilising enhanced materials and components. This proposal is based on adopting alkaline anion-exchange membrane (AEM) and ionomer (AEI) technology to open up the opportunity for low cost electrolysers systems with: i) low cost polymer electrolytes, catalysts (sustainable i.e. non-Pt), and bipolar plate materials; ii) higher energy efficiency; iii) durable long life operation; and iv) flexibility to respond to dynamic load operation. We target electrolysers involving hydrogen production from water electrolysis and involving carbon dioxide reduction for low overpotential (high value) organic chemical synthesis. A major aim is to produce the next generation of AAEMs and AEIs that can be supplied to (current and future) project partners in bulk quantities (including AEIs in a solubilised form).

Hydrogen is an excellent storage medium for renewable and sustainable energy systems. Hydrogen has several advantages as an energy carrier including highly efficient reversible conversion between hydrogen and electricity, good gravimetric energy density of compressed gas compared to most batteries and scalability of hydrogen technologies for grid scale applications. Water electrolysis is a safe option for production of pure hydrogen at point of use as it does not require substantial storage requirements.
Currently, the cost of hydrogen produced by electrolysis is greater than that of other methods such as steam reforming. Two major reasons for this is the capital cost of the cells and the electrical energy consumption. Commercial hydrogen production by water electrolysis is based on one of two technologies: aqueous alkaline (potassium hydroxide) electrolytes and proton exchange membrane electrolytes. Alkaline cells use lower cost electrode materials than acid polymer systems but current densities (and efficiency) are typically lower. The capital cost of proton exchange membrane electrolysers is higher (largely dictated by the high material costs of membranes [perfluorinated polymers] and precious metal [Pt, Ir, Ru] based catalysts) but their production rates (per unit electrode area) are higher based on the higher current densities. We thus seek to transform the latter technology by combing the advantages of alkaline and polymer electrolytes using low cost materials with the aim of improving energy efficiencies. Realistically there is a minimum energy consumption that can be achieved by electrolysis (based on thermodynamic potentials and voltage losses in the cell) and thus we set our target at a voltage of 1.75 V at 1 A cm-2 (based on geometric electrode area).
To maximise the potential impact of the materials being developed, carbon dioxide reducing electrolysers will also be studied (involving the field of carbon dioxide utilisation). The reduction of carbon dioxide into useful chemicals is of great potential value from a sustainability, environmental and societal context. Such syntheses require a significant energy use and thus using renewable electrical energy in such applications could play a major part in their development. Consequently we seek to develop electrochemical technology whereby we synthesis small molecules (formate, synthesis gas, and/or methanol) based on anion exchange membrane electrolyser materials and architectures (including the involvement of carbonate anion conducting electrolytes - which inherently yield higher chemical stabilities compared to hydroxide conducting analogues).
The project aims to deliver a step change in uptake of ultra-low carbon, green-hydrogen production and carbon dioxide reduction systems. This will be based upon the application of the applicants previous technology breakthroughs of alkaline polymer electrolyte materials and non-precious metal catalyst for galvanic and electrolytic electrochemical energy conversion and storage technologies.