The effect of inhomogeneous humidif

The effect of inhomogeneous humidification on the local aging of the membrane electrodeassemblies (MEAs) was investigated using segmented fuel cells under current cyclingconditions. The active area of the MEA was divided into 8 segments along the flow channels. The effects of the local humidification of the MEA were measured by the highfrequency resistance (HFR). It was found that the HFR of the first segment was largest dueto the lower humidification. The concentration of water and water vapor was higherdownstream, the MEA was humidified, and consequently the value of HFR also decreased.The fuel cells were operated at 60% RH, cell temperature 60 ℃ for uniform cell performance, with current cycling between 700 and 70 mA/cm2. The polarization curve showedless differentiation between each segment after 450 cycles and 150 hours of the currentloading test. The MEA was exposed to cycling expansion and contraction during the dryingand humidification processes, respectively. The results suggest that the membrane mightexperience mechanical degradation in downstream segments. In addition, the slope of thecyclic voltammetry (CV) curves increased from region 6 to region 8. The surface area of the catalyst also decreased due to the downstream water flooding, which might block the mass transfer and result in fuel starvation, carbon corrosion and catalyst degradation.