The challenge
Hydrogen fuel cells convert the energy in hydrogen fuel directly into electricity by combining it with oxygen to make water. Conversely, electrolysers use electricity to split water and generate the hydrogen fuel.
These devices play an important role in the implementation of a sustainable energy infrastructure. Fuel cells are used to power hydrogen cars and have the potential to disrupt a variety of industries, helping to reduce our reliance on fossil fuels and mitigating problems of pollution such as poor air quality.
However, the performance of fuel cells and electrolysers can suffer if the reaction is not uniformly distributed across the cell. Non-uniform distributions make inefficient use of expensive catalysts and can lower performance. They also arise naturally during start-up and shut-down of the cell, leading to reactions that increase the risk of corrosion and harm the useful lifetime of the device.
The solution
To better characterise reaction distributions in fuel cells, we developed an innovative reference electrode for polymer electrolyte membrane (PEM) fuel cells and electrolysers. By connecting a reference electrode directly to the electrode using a novel Nafion salt bridge configuration, the design allowed, for the first time, the accurate mapping of electrode potential across the active area of the cell. It also allowed separation of the contribution of each electrode to the overall performance of the cell.
The impact
The in situ reference electrode has led to major advances in fundamental understanding of degradation mechanisms associated with start-up/shut-down in fuel cells and electrolysers and bipolar plate corrosion. The impact of this work has been to change the approach of industry to materials qualification for hydrogen applications through the definition of more representative ex situ test conditions
The measurement technique has been adopted by UK manufacturers Intelligent Energy, Johnson Matthey, ITM Power, Acal Energy and Amalyst for optimisation of catalyst and hardware design to improve the lifetime of their products in this emerging market. An independent Technologia case study estimated that the impact of this innovation would lead to equivalent carbon savings of 0.4 megatonnes.