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

燃料电池是将化学反应的化学能直接转化为电能的电化学装置。尤其是质子交换膜燃料电池(PEMFC)是一个非常有意义的领域。这是因为它们非常多才多艺。例如，它们可以用于便携式能源、固定能源生产和交通运输等应用。此外，它们还有可能在未来的“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。气体扩散层是质子交换膜燃料电池的关键部件。GDL在质子交换膜燃料电池运行中的作用是多方面的。它提供了一种介质，反应气体可以通过它扩散，同时允许多余的液态水被去除。GDL还促进了通过PEMFC的热和电子传递。此外，它还为脆弱的催化剂层和膜提供机械支撑。GDL是催化剂和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，在质子交换膜燃料电池中，GDL仍然是一个相当大的运行损失领域，特别是欧姆损失。这些损失在燃料电池内组件之间的界面接触时变得更加严重；这对GDL尤其重要，因为它位于双极板和催化层之间。接触界面处的电损耗，例如GDL和双极板之间以及GDL和催化层之间的电损耗，明显高于单个元件的体损耗值。为了提高GDL在与催化层的界面接触处的性能，通常使用微孔层(MPL)。通常，MPL由碳颗粒与聚四氟乙烯和粘结剂混合组成。事实证明，MPL可以改善GDL在催化层界面的整体性能，包括改善电接触。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)来提高PEMFC的性能。这将通过在GDL上涂上双面MPL来实现。一个MPL将面向催化层，另一个将面向双极板。降低质子交换膜燃料电池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来降低ICR来降低欧姆损耗的方法仍然不完全清楚。将特别注意异地表征测量，因为这些测量将有助于从整体上了解GDL。本研究旨在更深入地了解ICR和开发替代GDL涂层的MPLS，以改善界面特性。此外，还打算探索用于MPL涂层的新材料，如碳纳米管和石墨烯。发展新的材料组合和不同的设计是为了减少界面接触电阻，增加电导率，从而改善PEMFC的整体性能。该项目的目标分为三个主要部分：准确地量化GDL与流场板之间以及GDL与催化层之间的界面接触电阻。通过考察PEMFC的特性和整体性能来优化双面MPL涂层GDL。根据特性和整体PEMFC性能优化双面MPL涂层GDL中使用的新材料。

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.