Macromolecular antioxidants for chemically durable polymer electrolyte fuel cell membranes

Abstract

Summary We investigated macromolecular antioxidants to improve the stabilities of polymer electrolyte membranes during fuel cell operation. Fenton's oxidative test was conducted to screen the scavenging activities of five different antioxidants, and Fourier transforms infrared spectroscopy and fluoride emission, conductivity, and tensile strength analyses were employed to monitor their effects on membrane degradation. The proton conductivities and water absorption of the composite membranes were comparable to those of the pristine membrane, which may overcome issues with metal antioxidants. Moreover, open‐circuit voltage (OCV) studies confirmed their positive effects during fuel operation. The OCV study showed that the membrane containing macromolecular antioxidants maintained a higher OCV than the pristine Nafion membrane, as verified by in situ analysis. Therefore, macromolecular antioxidants are useful for increasing the chemical durabilities of fuel cell membranes.

Numerical investigation of gas cross‐over and hydrogen peroxide formation in hydrocarbon‐based fuel cell membranes

“…Drawing on our previous study, 41 the proton conductivity (σ þ ) of Nafion and SPEEK membranes have been 21) and (22), respectively. In Equation ( 22), d represents SPEEK density.…”

“…PEMs suffer mechanical stresses induced by RH fluctuation, temperature mismanagement, and poor fabrication of MEA 13,21 . Secondly, the inevitable generation of reactive radicals within the membrane during PEFC operation and their intrinsic propensity for hydrogen abstraction result in chemical degradation of PEMs which manifests itself as defect and pinhole formation 22,23 . Although the hydroxyl ( ˙ OH) and hydroperoxyl ( ˙ OOH) destructive intermediates can be formed directly within the PEM, the most likely path for radical formation is reportedly the hydrogen peroxide (H 2 O 2 ) decomposition while metal transition ions, for example, Fe 2+ , are present 24 …”

“…13,21 Secondly, the inevitable generation of reactive radicals within the membrane during PEFC operation and their intrinsic propensity for hydrogen abstraction result in chemical degradation of PEMs which manifests itself as defect and pinhole formation. 22,23 Although the hydroxyl (˙OH) and hydroperoxyl (˙OOH) destructive intermediates can be formed directly within the PEM, the most likely path for radical formation is reportedly the hydrogen peroxide (H 2 O 2 ) decomposition while metal transition ions, for example, Fe 2+ , are present. 24 Along with the above-mentioned radicals, other intermediates such as ˙H have been detected in an in situ fuel cell test working with Nafion and SPEEK membranes by the spin-trapping electron spin resonance (ESR) technique.…”

Adsorption of Methylene Blue on the Surface of Polymer Membrane; Dependence on the Isotopic Composition of Liquid Matrix

“…The problem of increasing the durability of the polymer membrane as a fuel cell element while suppressing the membrane degradation is very clear. This can be achieved, for example, by adsorption of various antioxidants on the membrane surface; see recent works [ 9 , 10 ].…”