Improved Water Management for PEFC with Interdigitated Flow Fields using Modified Gas Diffusion Layers

Abstract

Polymer electrolyte fuel cells (PEFCs) with interdigitated flow fields were operated with modified gas diffusion layers (GDLs). Interdigitated flow fields have dead-ended channels, which forces the gas to flow convectively through the GDLs to the outlet channels and significantly reduces the mass transport losses. However, when using conventional GDLs, the water accumulation at the end of the inlet channels results in an increased and unpredictable pressure drop, which translates in unstable performance. This has prevented so far the use of this kind of flow fields in a stack configuration. Here, we show how GDLs optimized for water management with designed hydrophilic lines facilitate the transport of water from the dead ends to the outlet channels, which results in a lower and predictable pressure drop and in a stable performance. The voltage and pressure drop measurements were complemented by liquid water distribution measurements using high resolution neutron imaging to elucidate the water transport mechanisms. The stable pressure drop obtained with our customized GDLs allows to expect this configuration to be suitable for stack operation, opening the way to bring the benefits of interdigitated flows fields – high power density with low mass transport losses – to real fuel cell systems.