Electrodes by Design - Microstructural Engineering of High Performance Electrodes for Solid Oxide Fuel Cells

The electrode, and the electrolyte-electrode interface, plays a critical role in the performance of all cells. In Solid Oxide Fuel Cells (SOFCs) the microstructures of the porous composite anode and cathode are particularly critical as they determine the electrochemical, electrical, mechanical and transport properties of the electrode, and of current distribution to/from the electrode/electrolyte interface. Current state of the art SOFC electrodes rely on a largely empirical understanding to establish the electrode microstructure, and its influence on key performance characteristics, including long term durability. But recent work by the proposers has established a new suite of tools and techniques that offer the prospect of moving towards a design led approach to manufacture of improved electrodes, based on our ability to image, model, simulate and fabricate new electrode structures with controlled properties. This proposal seeks to develop and demonstrate this, further improving and validating our analysis and modelling tools, using these design optimum structures, fabricating these using three novel processing techniques established by the proposers, and then measuring device performance to feedback into the design process.

Our work will have impact on the fuel cell research community in academia and industry, and more widely to those interested in understanding and developing materials where microstructure plays a critical role in determining performance. There will also be wider impact to those interested in functional materials based around porous composite materials (e.g. batteries). The academic research community will benefit from the characterisation and modelling tools and techniques that we will continue to pioneer, extend and validate, the new nanoceramic powders that we will produce, and the new electrode fabrication processes that we will explore and develop. The fuel cell industry will benefit from the fundamental understanding that this work generates, as well as the design tools that we will establish to support the development of improved fuel cell electrodes, and that we will specifically work to translate into industry.

In addition to our engagement with a wide range of stakeholders through the H2FC SUPERGEN Hub, we have key industry partners working alongside us within this proposal. This provides us a clear route to ensure that our work has maximum relevance and impact. As Dr Mark Selby of our partner Ceres Power notes "Engineering microstructural properties of actual electrode structures in terms of their electrochemical, mechanical and transport properties are critical to achieving a low cost, high efficiency product. Additionally, understanding the evolution of these properties over time is important to designing long life products. I view learning that generates mechanistic and predictive models of restructuring over long time scales as one of the grand challenges in this research and development area.... There is a dearth of information and understanding in this area useful to the industrial community." The other leading SOFC developer, Rolls Royce Fuel Cell Systems, also support the proposal, regarding this work as "leading to more cost effective products". The broader impacts to the fuel cell sector are further highlighted by our partner AFC Energy. AFC Energy are a UK developer of alkaline fuel cells, but as AFC make clear "the experimental approaches to be further developed in the proposal, as well as the modelling, simulation and design tools that will result, will also have applicability to alkaline fuel cell electrode design ... we have similar design challenges around optimising coupled gas transport, electron transport, ion transport and electrochemical kinetics in porous composite electrode materials. Hence we are delighted that you have also recognised these broader spillover benefits, giving us the chance to input to the proposal and to work with you and your team to apply the research outputs to materials of our interest." Wider benefits are also highlighted by our partner Praxair, a developer in the strongly related field of Oxygen Transport Membrane (OTM) technology, who comment "Whilst we are in the process of commercializing several OTM technologies there are a number of fundamental materials issues that remain to be addressed, including durability, reliability and mechanical integrity.. It is exciting to see that you will be developing novel techniques, such as 4D tomography, microstructure modelling and novel manufacturing strategies, all of which will be applicable to OTM materials, and will help to establish performance/microstructure relationships for our materials, and furthermore to establish how they degrade over time."

We have also secured the support of Zeiss, a leading supplier of X-ray microscopy equipment. Zeiss provide a means for us to translate our advances in X-ray tomography experimental methodology into practice through this supply chain, making it available to others.