Novel diagnostic tools and techniques for monitoring and control of SOFC stacks - understanding mechanical and structural change

The Republic of Korea has world leading expertise in the deployment and scale up of Solid Oxide Fuel Cell (SOFC) technologies. The UK has world class expertise in underpinning science and engineering of SOFC materials and devices. Large-scale trials by HK Oil and others have revealed unsatisfactory durability at steady state operating conditions in the anode supported SOFC stacks under development in Korea, as well as poor tolerance to thermal cycling.

This reflects that fact that scaling up SOFC technology introduces additional challenges related (in particular) to non-uniform distribution of reactants, products and temperature within the fuel cell stack. Some steady state degradation can be attributed to classical SOFC issues of cathode poisoning, phase segregation and anode Ni coarsening. However, rapid failure, cycling intolerance and step changes in performance are most likely associated with mechanical issues. Understanding the thermal and mechanical environment of the cells in a stack under different conditions and during cycling is therefore key to improving the design and the operating regime of the system to give maximum durability, as these can manifest as additional mechanical and chemical strains within the ceramic materials used for SOFC fabrication, resulting in degradation and in extreme cases failure. Commercial development of SOFC stacks and systems requires a reduction in degradation rate, and an increase to mean time to failure.

To address this it is necessary to be both able to monitor the conditions within the fuel cell stack, relating these to state of health, and then using this information to better control the system to maintain stack life, or engineer a controlled shut down so that components can be replaced, extending system life. These advanced monitoring techniques when coupled with validated predictive simulation capability will allow new cell and stack configurations to be developed for high durability and performance.

This proposal seeks to develop two novel diagnostic techniques, pioneered by UK partners, and apply them to advanced cell testing and characterisation at partners in Korea . The measurements are used to validate models developed in the UK to relate the measured data to degradation and failure modes, transferring this to Korean partners to offer the potential for real time monitoring and control of SOFC stacks. This will give valuable understanding required to refine and develop the next generation of SOFC systems in the most time efficient manner, and have wider impact on UK and other international developers. The programme will support an exchange of researchers between the UK and Korean partners, supported by two research workshops in the UK, and one in Korea.

Our work will have impact on the academic SOFC research community, SOFC developers in industry, and more widely to those interested in understanding and developing engineered products based electro-ceramic materials such as ceramic oxygen membranes and electrolysers, where thermal issues impact critically on material, device and product lifetime. We will ensure that our work has maximum impact to both the academic and industry communities through high quality peer reviewed publications, presentations at key conferences in the field, and engagement through the Hydrogen and Fuel Cell SUPERGEN Hub to disseminate our research, and by dual language summaries of our research outputs that we will make widely available. We will organise a final project workshop in partnership with the H2FC SUPERGEN Hub to discuss the key outputs from our work, and to disseminate learning from the research to stakeholders. We will further ensure that research outputs and learning are disseminated through the the POSTECH institute of new and renewable energy (INRE), and the Korean national hydrogen fuel cell test-bed centre. These multi-disciplinary Institutes bring together researchers to address wide ranging challenges across the energy sector in both the UK and Korea. Indeed, the Directors of both H2FC SUPERGEN and the Korean national fuel cell test-bed centre are Investigators on this proposal, Brandon in the UK, and Chung in Korea, ensuring strong participation at the national level, and providing a clear route to wider dissemination and research translation.

In addition to our engagement with a wide range of stakeholders described above, we are working directly with H K Oil Ltd as an industry partner in this proposal. This provides us a clear route to ensure that our work has maximum relevance and impact, and (critically for work of this type) access to long term testing and a supply of technologically relevant cells and short stacks. In return H K Oil gain insight from the test and characterisation capability with leading research partners at POSTECH and KIER in Korea, and sensors, diagnostic and modelling expertise in the UK at Loughborough, Imperial and Lancaster respectively.

Where our research work has potential for commercial impact we will ensure that the necessary intellectual property is protected by patents. For example Imperial (inventors Brandon, Yufit and others) have already patented the FAZE approach to be further developed and extended to SOFCs in this proposal (previously this has been demonstrated only for lithium battery technology), and hence licensing opportunities exist to the SOFC industrial sector if the value of the innovation can be demonstrated through longer term testing (something very difficult to achieve in UK academic laboratories). Similarly, our industry partner H K Oil Ltd gains the advantage of improved lifetime of cells and stacks through translation and implementation of the research outcomes proposed in this study, offering technology advantage. Through publication and wider dissemination of the research outcomes, other developers will subsequently benefit from the research, and improve their tolerance to, and management of, thermal cycling and temperature gradients.

A further key impact of this proposal will be in the training and development of highly qualified personnel, familiar with the research culture in both the UK and Korea.

Finally, the proposal will strengthen the emerging ties and links between the UK and Korea in the fuel cell sector. The proposers have been deeply involved in the development of this relationship to date. Brandon and Chung led the development of the UK-Korea MOU in fuel cells, signed on Nov 6th 2013, following two exchange visits between both investigators. Brandon led the UK delegation to the joint workshop in Seoul where the call was discussed, and this proposal directly arose from that, in which Kim, Dawson, Song and Chung were all invited participants.