Humidity can affect the attenuation of MEA (membrane electrode assembly)

however

the relationship between humidity and MEA decays is complex and ambiguous in realistic application. Herein

we design a simulating automotive protocol

performed on five single fuel cells under RH (relative humidity) 100%

RH 80%

RH 64%

and RH 40%

RH 10%

respectively

to study the relationship of MEA decays and humidity and suggest optimized humidity range to extend the durability. With the electrochemical impedance spectroscopy

cyclic voltammetry

X-ray fluorescence

X-ray diffraction

transmission electron microscope

X-ray photoelectron spectroscopy

the four degradation mechanisms about catalyst layer

including Pt dissolution

Pt coarsening

carbon corrosion and ionomer degradation

are observed. Pt coarsening and carbon corrosion are accelerated by higher water content at high humidity. Ionomer degradation and Pt dissolution are enhanced in low humidity. With the linear sweep voltammetry

ion chromatography

nuclear magnetic resonance

tensile test and scan electron microscope

chemical and mechanical degradation in proton exchange membrane are all observed in these five fuels. Chemical degradation

characterized by membrane thinning and more fluoride loss

occurred markedly in RH 10%. Mechanical degradation

characterized by the non-uniformity thickness and bad mechanical properties

is more pronounced in RH 100%

RH 80%

RH 64%. These two degradations are in a moderate level in RH 40%. The research suggests that the RH range from 64% to 40% is conductive to mitigate the degradation of MEAs operated in automotive applications.