Understanding Charge, Mass, and Heat Transfer in Fuel Cells for Transport Applications – Insights from the Camelot Project

Abstract

Proton Exchange Membrane Fuel Cells (PEMFCs) are a promising solution for zero-emission vehicle propulsion owing to their high energy density, low operating temperature, and high efficiency. The overall aim of the CAMELOT project is to improve the power density of fuel cells by understanding the limitations on the performance of state-of-the-art (SoA) and beyond SoA PEMFC membrane electrode assemblies (MEAs). To achieve this, the CAMELOT project has diagnosed the fundamental transport properties that limit performance of these MEAs and materials. Not only has the CAMELOT project produced MEAs with features that have the potential to enable disruptive performance increases but have further developed leading open-source models to enable accurate simulations validated through experimental work. In-depth parametrisation of fuel cell components through extensive ex-situ and in-situ characterisation has been performed to provide input to the modelling activities. The two major modelling advances achieved by the CAMELOT project are i) the improvement of water uptake and transport models, especially concerning ultra-thin PEMs, and ii) extending a leading open-source model (FAST-FC) to enable accurate simulation of beyond SoA fuel cell performance and voltage loss breakdown. CAMELOT has developed a series of beyond-SoA fuel cell components to ensure that the modelling inputs are representative of SoA component properties. A series of membranes with varying thicknesses were prepared and a range of ex-situ experiments were carried out to gather water uptake and permeability properties for the water transport models. Additional in-situ electrochemical characterisation was carried out on a series of catalyst coated membranes (CCMs) to extract important properties of the catalyst and membrane components as inputs to improve the physics-based fuel cell performance model.Significant results from the project to be highlighted in this presentation include the development of a water transport model with improved description of water uptake and transport in thin ionomeric layers, the development of a predictive modelling framework from which we can identify the most important material parameters to tune to reach our MEA performance targets of 2.7 A/cm2 at >0.67 V with total catalyst loadings <0.08 mgPt/cm2, the development of ultrathin (< 10 µm) proton exchange membranes and ultra-low loading cathode catalyst loadings (0.08 mgPt/cm2), the development of catalyst coated membranes (CCMs) with in-plane catalyst and ionomer gradients, and extensive in-situ fuel cell characterization of the SoA CAMELOT CCMs/MEAs.The CAMELOT project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under grant agreement No 875155. This Joint Undertaking receives support from the European Union’s Horizon 2020 Research and Innovation program, Hydrogen Europe and Hydrogen Europe Research.