Effect of membrane electrode assembly characteristics on the performance of a proton exchange membrane fuel cell stack designed for unmanned aerial vehicle applications

Abstract

ABSTRACT A proton exchange membrane fuel cell stack designed for unmanned aerial vehicle applications was used to evaluate the influence of several membrane electrode assembly (MEA) characteristics. MEAs prepared with catalytic layers (CLs) deposited directly on the membrane presented slightly better performance than those with CLs deposited in the gas diffusion layers (GDLs). Thinner membranes were beneficial to the stack performance due to lower activation and ohmic losses. Increasing the Pt loading on the cathode side from 0.5 to 2.0 mg Pt cm−2 did not improve the performance. Small differences were observed between carbon cloth and carbon paper GDLs, possibly due to the presence of a microporous layer (MPL). The hydrophobic treatment of the GDLs improved the performance due to a better humidification of the MEAs. The MPL was found fundamental for a high performance due to an improvement in the electric contact, decreasing ohmic losses. The stack operation under realistic conditions, consisting of a transient energy profile typical of an UAV flight, was also investigated. The stack presented higher dynamic performance than its steady-state one at low currents but slightly lower at high currents. Differences in temperature were observed, which probably contributed to this disparity.