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

燃料电池是一种电化学装置，它能将反应中的化学能直接转化为电能。质子交换膜燃料电池（PEMFC）是一个备受关注的领域。这是因为它们非常通用。例如，它们可用于便携式能源、固定式能源生产和运输等应用。此外，它们可能在未来的“氢经济”中发挥重要作用。这包括为减少温室气体排放和减少对化石燃料技术的依赖做出贡献。气体扩散层（GDL）是PEMFC的关键部件。GDL在PEMFC操作中的作用是多方面的。它提供了一种介质，通过这种介质，反应物气体可以扩散，同时允许除去多余的液态水。GDL还促进了热和电子通过PEMFC的传递。此外，它还为精致的催化剂层和膜提供机械支撑。GDL是催化剂与双极板之间的重要介质；这导致了对GDL性能的大量研究。尽管如此，在PEMFC中，GDL仍然是一个相当大的操作损耗区域，特别是欧姆损耗。这些损失在燃料电池组件之间的界面接触处变得更加重要；这对于GDL尤其重要，因为它位于双极板和催化剂层之间。在GDL和双极板之间以及GDL和催化剂层之间的接触界面上的电损耗明显高于单个组件的体积损耗。为了提高GDL在与催化剂层接触界面处的性能，通常采用微孔层（MPL）。通常，MPL由碳颗粒与PTFE和粘合剂混合组成。MPL已被证明可以改善GDL在催化剂层界面的整体性能，包括改善电接触。本研究的主要目的是通过应用双面MPL涂层GDL来降低界面接触电阻（ICR），从而提高PEMFC的性能。这将通过在GDL上涂覆双面MPL来实现。一个MPL将面对催化剂层，另一个将面对双极板。降低PEMFC的欧姆损耗一直是许多研究小组关注的焦点。然而，通过使用双面MPL涂层GDL降低ICR来降低欧姆损耗仍然没有完全了解。将特别注意非原位特征测量，因为这些将有助于对GDL的整体理解。本研究旨在为ICR和替代GDL涂层MPLs的发展提供更深入的见解，以改善接口特性。此外，还将探索新型材料，如碳纳米管和石墨烯，用于MPL涂层。开发新的材料组合和不同的GDL设计旨在降低界面接触电阻，提高导电性，从而提高PEMFC运行的整体性能。本项目的目标主要分为3个部分：准确量化GDL与流场板之间以及GDL与催化剂层之间的界面接触阻力。通过检查PEMFC的特性和整体性能来优化双面MPL涂层GDL。通过特性和整体PEMFC性能优化双面MPL涂层GDL中新材料的使用。

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.