Rigid-Rod Poly(phenylenesulfonic acid) Proton Exchange Membranes with Cross-Linkable Biphenyl Groups for Fuel Cell Applications

Abstract

Biphenyl was grafted on rigid-rod aromatic poly(p-phenylenesulfonic acids) (IEC ∼ 8 mequiv g −1 ) to generate cross-linkable polyelectrolytes. Cross-linking conditions and film properties before and after cross-linking were studied. Films equilibrated between 20 and 30% relative humidity (RH) had tensile moduli of 2 to 1 GPa and broke at 5 to 9% elongation. The moduli decreased as RH increased and dropped drastically at high humidity if the films were not cross-linked. Grafted films had conductivities at 80 °C 4−5 times that of Nafion NR-212 over the whole relative humidity range even after cross-linking. The sample reported in detail here had a conductivity of 0.10 S cm −1 at 120 °C and 30% RH. As is usual for this class of materials, even after the loss of 24% of starting sulfonic acid groups by grafting and cross-linking, ionic conductivity was high at low humidity. A membrane electrode assembly (MEA) prepared with this rigid-rod poly(phenylenesulfonic acid) proton exchange membrane and tested in a fuel cell exhibited performance and properties similar to those of Nafion NR-212 films. The power density was ∼95% of that of the Nafion MEA over the operating range in spite of relatively high hydrogen crossover due to the presence of nanocracks in the membrane.

Hexafluoroisopropylidene based sulfonated new copolytriazoles: investigation of proton exchange membrane properties

“…As a core component of the proton exchange membrane fuel cells (PEMFCs), the proton exchange membrane (PEM) acts as a proton transporter and provides a barrier for the reactant and the catalyst support (1)(2)(3)(4). At present perfluoro sulfonated ionomers, for example: Nafion ® , Flemion ® , Dow ® and Aciplex ® are commonly used as a PEM material, due to its high chemical and mechani cal stability along with its high proton conductivity (5,6).…”

Proton-conductive nano zeolite-PVA composite film as a new water-absorbing electrolyte for water electrolysis

“…The frequency range was 1 MHz to 0.1 Hz with an applied voltage of 100 mV. For through-plane proton conductivity measurements of the composite films, 740 Membrane Test System (MTS, Scribner Associates, Inc.) was used with a through-plane measurement attachment (740 Cell Head) and a Solatron 1260 impedance meter (Solatron, UK) [17]. The current, voltage and frequency range used were 0.1 mA, 1 V and 10-10 6 Hz, respectively.…”

The sulfonated poly(phenylene) membranes containing multi-phenylrings prepared by nickel catalyst

“…However, the chemical stabilities of ether sulfone polymers are unapproachable to Nafion, because of ether linkage with acid functional groups was easily attacked by nucleophiles at operating PEMFC system [14]. In order to redeem the fault, many researcher, Ghassemi and coworkers [15], Zhang and co-workers [16], Linivin and co-workers [17], Si and co-workers [18] were studied carbon-carbon coupling reaction with metal catalyst. Chemical degradation of membranes is considered as a major concern for fuel cell performance.…”

“…The introduced multi pendant phenyl rings effect on the improvement of morphology and properties. Moreover, polymers with pendant benzoyl group improve molecular weight due to symmetrical monomer and have some advantages, such as good solubility, durability and thermooxidative stability [10,[15][16][17][18]. The proposed polymer membranes containing no-ether linkage, multi-phenyl, and benzoyl structures were desirable monomer units to good chemical stability, morphology, and proton conductivity.…”