Preparation and Properties of Cross‐linked Sulphonated Poly(sulphide sulphone) Membranes for Fuel Cell Applications

Abstract

A series of cross‐linked sulphonated poly(sulphide sulphone) (SPSSF) membranes have been prepared via a polyphosphoric‐acid‐catalysed condensation reaction at 180 °C for a period of time (1.5–5.0 h) and the resulting cross‐linking bonds are the highly stable sulphonyl groups. The cross‐linking density could be controlled by regulating the reaction time. Cross‐linking caused significant enhancement in the mechanical properties and large reduction in both water uptake (WU) and methanol permeability. The SPSSF‐60 membrane (the numeral 60 refers to the degree of sulphonation), e.g. had a tensile strength increased from 16 to 27 MPa (wet membranes) after cross‐linking for 5 h, while the WU substantially decreased from 320 to 58 wt.‐% and the methanol permeability decreased from 1.9 × 10–6 to 2.7 × 10–7 cm2 s–1 (30 °C). Single cell test on hydrogen/oxygen revealed that the cross‐linked SPSSF‐50 (1.5 h) membrane displayed higher open circuit voltage (OCV, 1.02 V), higher maximum output power density (1.32 W cm–2) and significantly slower OCV decay rate than the uncross‐linked SPSSF‐40 membrane under the same operating conditions despite their similar ion exchange capacities. The cross‐linked SPSSF‐60 (5.0 h) and SPSSF‐50 (1.5 h) membranes showed significantly better fuel cell performance than Nafion 212.

Preparation and properties of covalently cross-linked sulfonated poly(sulfide sulfone)/polybenzimidazole blend membranes for fuel cell applications

“…SPSSF80 and SPSS with 50% degree of sulfonation (SPSSF50) were synthesized via random copolymerization of 4,4 0 -dichlorodiphenyl sulfone-3,3 0 -disulfonic acid disodium salt, DCDPS, and TBBT in DMAc at 160 C for 20 h following the experimental procedures described in the literature. 5 H 2 N-PBI was synthesized via the condensation polymerization of the AIPA and DAB in polyphosphoric acid at 185 C for 24 h according to a literature method. 24 The chemical structures of the SPSSFs and the H 2 N-PBI are shown in Figure 1.…”

“…So far, a huge number of sulfonated aromatic hydrocarbon polymer membranes have been extensively studied such as sulfonated poly(ether sulfone)s, sulfonated poly(ether ether ketone)s, sulfonated poly(sulfide sulfone)s (SPSSs), sulfonated polyimides, sulfonated (aryl ether)s, and sulfonated poly(phenylene)s. In general, sulfonated hydrocarbon polymer membranes are cost-effective and part of them have been reported to show better fuel cell performance than Nafion under the same operation conditions. [1][2][3][4][5][6][7][8][9][10] However, in comparison with Nafion sulfonated hydrocarbon polymers generally have the drawback of poor chemical stability, in particular, the radical oxidative stability, leading to short lifetime of the fuel cells. It has been identified that the radical oxidation-induced polymer degradation is the main reason for the deterioration of fuel cells.…”

“…The mechanical properties, water uptake (WU), SW, proton conductivity, and radical oxidative stability of the blend membranes are also investigated. The selection of the SPSSF80 is based on the consideration that the fuel cells equipped with the SPSSF membranes show higher output power density than that of Nafion under the same conditions, 5 while the use of the H 2 N-PBI is because it has good solubility in common aprotic solvents 24 and the pendant amino groups are useful functional groups for covalent cross-linking. It is expected that the covalent cross-linking can further suppress membrane swelling and enhance the radical oxidative stability.…”

Synthesis, proton conductivity and chemical stability of novel sulfonated copolyimides-containing benzimidazole groups for fuel cell applications

“…180 C) for a period of time. [33][34][35] The cross-linking mechanism is based on the phosphorus pentoxide-catalyzed condensation reaction between the sulfonic acid groups and the activated benzene rings. The key merit of this cross-linking technique is that it is unnecessary to introduce special crosslinkable groups into polymer structure but just to use small part of the sulfonic acid groups and thus complicated synthetic procedures are avoided.…”

Cross-linked membranes with a macromolecular cross-linker for direct methanol fuel cells

“…Xu et al prepared cross-linked membranes via a condensation reaction of sulfonic groups. 19 This method involved the elimination of sulfonic acid, which resulted in the decline of the IEC and proton conductivity. Phu and co-workers have recently reported a cross-linked membrane using 4,4 0 -oxybis(benzoic acid) as a cross-linker.…”