The Contact Resistance of a Double-Sided MPL Coated GDL used in PEMFC

Fuel cells are electrochemical devices that convert the chemical energy of a reaction directly into electrical energy. Proton exchange membrane fuel cells (PEMFC) are in particular, an area of substantial interest. This is due to the fact that they are very versatile. For example, they can be used in applications such as portable energy, stationary energy production and transportation. Furthermore, they potentially have an important role to play in the future "hydrogen economy". This includes contributing to reduce greenhouse gas emissions and decreasing the dependence on fossil fuel technologies.
The gas diffusion layer (GDL) is a critical component in the PEMFC. The role of the GDL in the operation of a PEMFC is multifaceted. It provides a medium through which the reactant gases can diffuse through, while simultaneously allowing excess liquid water to be removed. The GDL also facilitates heat and electron transfer through the PEMFC. Additionally, it provides mechanical support for the delicate catalyst layer and membrane.
The GDL is an important medium between the catalyst and bipolar plate; this has led to much research into the GDL performance. Despite this, the GDL is still an area of considerable operational losses in a PEMFC, particularly ohmic losses. These loses become more consequential at the interfacial contacts between components within the fuel cell; this is especially significant for the GDL as it sits in between the bipolar plate and catalyst layer. Electrical losses at the contact interfaces, such as, between the GDL and bipolar plate and the GDL and catalyst layer are significantly higher than individual component bulk losses.
To enhance the properties of the GDL at the interfacial contact with the catalyst layer, a microporous layer (MPL) is conventionally applied. Typically, the MPL consists of carbon particles mixed with PTFE and a binder. The MPL has been proven to improve overall performance of the GDL at the catalyst layer interface, including improvements in electrical contact.
The main objective of the research is to improve the performance of PEMFC by reducing the interfacial contact resistance (ICR) by the application of a double-sided MPL coated GDL. This will be achieved by coating the GDL with a double-sided MPL. One MPL will face the catalyst layer and the other will be facing the bipolar plate. Reducing ohmic losses of the PEMFC has been the focus of many research groups. However, the reduction of ohmic losses via the reduction of ICR using a double-sided MPL coated GDL is still not fully understood. Particular attention will be paid to the ex-situ characterisation measurements, as these will aid in holistic understanding of the GDL.
This study aims to provide greater insight into the ICR and the development of alternative GDL coated MPLs to improve interfacial characteristics. In addition, it is intended to explore novel materials for MPL coatings such as carbon nanotubes and graphene. The development of new combinations of materials and different designs for the GDL is aiming at reducing the interfacial contact resistance, increase electrical conductivity, thus improving the overall performance of PEMFC operation.
The objective of this project is divided into 3 main parts:

Accurately quantify the interfacial contact resistance between GDL and the flow field plate and between the GDL and the catalyst layer.
Optimise the double-sided MPL coated GDL by examining characterisation and holistic performance on PEMFC.
Optimise the use of novel materials for use in the double-sided MPL coated GDL by characterisations and overall PEMFC performance.

The proposed Centre will benefit the following groups

1. Students - develop their professional skills, a broad technical and societal knowledge of the sector and a wider appreciation of the role decarbonised fuel systems will play in the UK and internationally. They will develop a strong network of peers who they can draw on in their professional careers. We will continue to offer our training to other Research Council PhD students and cross-fertilise our training with that offered under other CDT programmes, and similar initiatives where that develops mutual benefit. We will further enhance this offering by encouraging industrialists to undertake some of our training as Professional Development ensuring a broadening of the training cohort beyond academe. Students will be very employable due to their knowledge, skills and broad industrial understanding.
2. Industrial partners - Companies identify research priorities that underpin their long-term business goals and can access state of the art facilities within the HEIs involved to support that research. They do not need to pre-define the scope of their work at the outset, so that the Centre can remain responsive to their developing research needs. They may develop new products, services or models and have access to a potential employee cohort, with an advanced skill base. We have already established a track record in our predecessor CDTs, with graduates now acting as research managers and project supervisors within industry
3. Academic partners - accelerating research within the Energy research community in each HEI. We will develop the next generation of researchers and research leaders with a broader perspective than traditional PhD research and create a bedrock of research expertise within each HEI, developing supervisory skills across a broad range of topics and faculties and supporting HEIs' goals of high quality publications leading to research impacts and an informed group of educators within each HEI. .
4. Government and regulators - we will liaise with national and regional regulators and policy makers. We will conduct research directly aligned with the Government's Clean Growth Strategy, Mission Innovation and with the Industrial Strategy Challenge Fund's theme Prosper from the Energy Revolution, to help meet emission, energy security and affordability targets and we will seek to inform developing energy policy through new findings and impartial scientific advice. We will help to provide the skills base and future innovators to enable growth in the decarbonised energy sector.
5. Wider society and the publics - developing technologies to reduce carbon emissions and reduce the cost of a transition to a low carbon economy. Need to ascertain the publics' views on the proposed new technologies to ensure we are aligned with their views and that there will be general acceptance of the new technologies. Public engagement will be a two-way conversation where researchers will listen to the views of different publics, acknowledging that there are many publics and not just one uniform group. We will actively engage with public from including schools, our local communities and the 'interested' public, seeking to be honest providers of unbiased technical information in a way that is correct yet accessible.