Influence of adjusted hydrophilic-hydrophobic lengths in sulfonated multiblock copoly(ether sulfone) membranes for fuel cell application

Proton conducting ABA triblock copolymers with sulfonated poly(phenylene sulfide sulfone) midblock obtained via copper-free thiol-click chemistry

The synthesis and characterization of novel proton conducting ABA triblock copolymers are reported. Structure-properties relationship of the block copolymers has been investigated at both the microscopic and macroscopic levels.

Cross-Linked Sulfonated Poly(arylene ether sulfone) Containing a Flexible and Hydrophobic Bishydroxy Perfluoropolyether Cross-Linker for High-Performance Proton Exchange Membrane

Here we show a simple and effective cross-linking method to prepare a high performance cross-linked sulfonated poly(arylene ether sulfone) (C-SPAES) membrane using bishydroxy perfluoropolyether (PFPE) as a cross-linker for fuel cell applications. The C-SPAES membrane shows much improved physicochemical stability due to the cross-linked structure and reasonably high proton conductivity compared to the non-cross-linked SPAES membrane due to the incorporation of flexible PFPE and the effective phase-separated morphology between the hydrocarbon and perfluorinated moieties forming well-connected networks. Under intermediate-temperature and low humidity conditions (90 °C, 50% RH, and 150 kPa), the membrane electrode assembly employing the C-SPAES membrane reveals an outstanding cell performance (1.17 W cm^-2 at 0.65 V) ascribed to its reasonably high proton conductivity and enhanced interfacial compatibility between the perfluorinated moieties in the electrode and C-SPAES membrane. Furthermore, a hydration-dehydration cycling test result at 90 °C reveals that the C-SPAES membrane has notable durability against rigorous operating conditions.

Fuel cell electrocatalyst using polybenzimidazole-modified carbon nanotubes as support materials

Toward the next generation fuel cell systems, the development of a novel electrocatalyst for the polymer electrolyte fuel cell (PEFC) is crucial to overcome the drawbacks of the present electrocatalyst. As a conductive supporting material for the catalyst, carbon nanotubes (CNTs) have emerged as a promising candidate, and many attempts have been carried out to introduce CNT, in place of carbon black. On the other hand, as a polymer electrolyte, polybenzimidazoles (PBIs) have been recognized as a powerful candidate due to the high proton conductivity above 100 °C under non-humid conditions. In 2008, we found that these two materials have a strong physical interaction and form a stable hybrid material, in which the PBIs uniformly wrap the surfaces of the CNTs. Furthermore, PBIs serve as effective binding sites for the formation of platinum (Pt) nanoparticles to fabricate a ternary composite (CNT/PBIs/Pt). In this review article, we summarize the fundamental properties of the CNT/PBIs/Pt and discuss their potential as a new electrocatalyst for the PEFC in comparison with the conventional ones. Furthermore, potential applications of CNT/PBIs including use of the materials for oxygen reduction catalysts and reinforcement of PBI films are summarized.

Sulfonated poly(ether sulfone ether ketone ketone)/sulfonated poly(ether sulfone) blend membranes with reduced methanol permeability

Proton exchange membranes were prepared by blending sulfonated poly(ether sulfone ether ketone ketone) (SPESEKK) with sulfonated poly(ether sulfone) (SPES). The morphology, tensile strength, proton conductivity and methanol permeability of the blend membranes were investigated. The scanning electron microscope and transmission electron microscope observation indicates the good dispersion of the SPES in SPESEKK polymer matrix. The addition of SPES also enhances the tensile strength of the SPESEKK membrane. The blend membrane shows lower methanol diffusivity and higher proton conductivity with comparison to the pure SPESEKK membrane, ascribing to the inhabitation of the player SPES to methanol permeation and facilitation of the increment of sulfonic acid groups to the proton transport. The SPESEKK/SPES 5 : 5 membrane exhibits an appreciable tensile strength of 52.3 MPa and a reduced methanol permeability of 6.6 × 10−7 cm2 s−1. This SPESEKK/SPES composite membrane shows a potential feasibility as a promising electrolyte for direct methanol fuel cells.

Structure-morphology-property relationships of non-perfluorinated proton-conducting membranes

A fundamental understanding of structure-morphology-property relationships of proton exchange membranes (PEMs) is crucial in order to improve the cost, performance, and durability of PEM fuel cells (PEMFCs). In this context, there has been an explosion over the past five years in the volume of research carried out in the area of non-perfluorinated, proton-conducting polymer membranes, with a particular emphasis on exploiting phase behavior associated with block and graft copolymers. This progress report highlights a selection of interesting studies in the area that have appeared since 2005, which illustrate the effects of factors such as acid and water contents and morphology upon proton conduction. It concludes with an outlook on future directions.

Polysulfone-based Ionomers for Fuel Cell Applications

This paper is a review that is focused on ionomers based on aromatic polysulfone backbone and intended to be used in proton exchange membrane fuel cells or in direct methanol fuel cells. Emphasis is placed on the different chemical routes to prepare the ionomers. Special attention is given to the impact of the ionomer structure on the conductivity performance and on the dimensional stability of the membranes at high temperatures.