In-Plane Mass-Transport Studies of GDL Variation Using the Segmented Cell Approach

摘要

The effects of cathode GDL variation on segmented cell performance were investigated using polarization analysis, AC impedance, and cyclic voltammetry. Three different SGL SIGRACET~? materials were used with markedly different PTFE treatments operating under 100%/100% and 50%/50% (anode/cathode) relative humidity (RH) conditions. The total cell performance varied little under both wet and dry operating conditions for three different GDL types, but performance differences were observed for individual segments based on polarization and AC impedance data. When the different GDL types were arranged in a mixed configuration, an improvement over the base case GDL 24BC (5/23 wt% PTFE substrate/MPL) of 11% and 8% in current density at 0.6 V was seen for wet and dry conditions, respectively. When the three different GDL types were compared for ECSA loss after 300 operating hours, the GDL 24BC5 (5/5 wt% PTFE substrate/MPL) exhibited the largest decline, which was attributed to increased Pt particle agglomeration. The cell with the mixed configuration showed an ECSA decline comparable to GDL 24BC (5/23 wt% PTFE substrate/MPL) and GDL 24D1 (20/10 wt% PTFE substrate/MPL). Therefore, it was demonstrated that moderate performance improvements can be realized by varying the in-plane GDL type in relation to its flow-field position without sacrificing durability.