Magnetic field alignment of stable proton-conducting channels in an electrolyte membrane

Abstract

Proton exchange membranes with short-pathway through-plane orientated proton conductivity are highly desirable for use in proton exchange membrane fuel cells. Magnetic field is utilized to create oriented structure in proton exchange membranes. Previously, this has only been carried out by proton nonconductive metal oxide-based fillers. Here, under a strong magnetic field, a proton-conducting paramagnetic complex based on ferrocyanide-coordinated polymer and phosphotungstic acid is used to prepare composite membranes with highly conductive through-plane-aligned proton channels. Gratifyingly, this strategy simultaneously overcomes the high water-solubility of phosphotungstic acid in composite membranes, thereby preventing its leaching and the subsequent loss of membrane conductivity. The ferrocyanide groups in the coordinated polymer, via redox cycle, can continuously consume free radicals, thus helping to improve the long-term in situ membrane durability. The composite membranes exhibit outstanding proton conductivity, fuel cell performance and durability, compared with other types of hydrocarbon membranes and industry standard Nafion® 212.

Polyoxometalate–Polymer Hybrid Materials as Proton Exchange Membranes for Fuel Cell Applications

“…For example, Uchida and Yin et al dissolved H 3 PW 12 O 40 ·nH 2 O, PEG1000 and CsNO 3 into water and obtained highly efficient proton-conducting POM–PEG crystalline hybrid materials, in which a single PEG chain was confined in the one-dimentional nanochannels defined by the frameworks of POMs [59,60]. Besides water, polar organic solvents such as alcohols and N, N-dimethylformamide which are able to make POMs and polymers a homogeneous solution, are also widely used in solution blending [61,62,63]. It should be noted that when dealing with water-insoluble polymers which cannot directly blend with POMs, solution swelling is also a constructive way to achieve the hybridization process.…”

“…The sole proton conductor, PWA was confined in the submicro-porous structure cross-linking the polymer matrix, which not only enhanced proton conductivity and mechanical properties but also reduced methanol permeability and the leakage of itself. Recently, Guiver and co-workers reported a magnetic field induced composite PEM containing through-plane-aligned proton channels with PWA arrays inside (Figure 7a) [62]. The PEM was co-casted by polysulfone and a water-insoluble proton-conducting paramagnetic complex formed by both water-soluble ferrocyanide-coordinated poly(4-vinylpyridine) (CP4VP) and PWA via electron transfer under the magnetic field.…”

Large‐Area Aminated‐Graphdiyne Thin Films for Direct Methanol Fuel Cells

“…It is understandable for this phenomenon because of the selectivity of NH 2 -GDYand the smaller ionic cluster near its surface.W ecan find that the variations of the proton conductivity follows the Arrhenius relationship of s = s 0 exp(ÀE a /kT). [18] In the equation, the s is the proton conductivity,t he E a is the activation energy.T he slope of the plot in Figure 3f reveals that the composite membrane has an E a of 6.255 kJ mol À1 ,which is slightly higher than the pure Nafion (4.786 kJ mol À1 ). Besides,the composite membrane has stable mechanical property (Supporting Information, Figure S27).…”

Recent Progress in the Development of Composite Membranes Based on Polybenzimidazole for High Temperature Proton Exchange Membrane (PEM) Fuel Cell Applications

“…Among this family of heteropolyacids, phosphotungstic acid (HPW), with molecular formula H 3 P 4 W 12 O 40 , has been efficiently applied as a proton carrier in proton exchange membrane fuel cells [ 60 , 61 ]. Some representative literature on heteropolyacid doped polymer as PEM should be consulted [ 62 , 63 ]. In a recent work, we have evaluated the long-term stability of PBI membranes doped with different concentrations of the widely used PA, and an important acid leaching and subsequent conductivity drop was observed [ 64 ].…”