Perfluorosulfonate ionomer membranes with improved through-plane proton conductivity fabricated under magnetic field

Tang, Junkun; Yuan, Wang Zhang; Wang, Jinhui; Tang, Junke; Li, Hong; Zhang, Yongming

doi:10.1016/j.memsci.2012.08.023

Cited by 24 publications

(19 citation statements)

References 36 publications

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“…Ostensibly, a shorter and less tortuous conduction pathway in the TP direction would increase the efficiency of proton transport from the anode to the cathode, thereby increasing PEMFC performance. So far, efforts to orient conductivity in the TP direction have been explored by electric field alignment 9–15 and magnetic field alignment 16–20 . Electric field alignment has been explored by incorporating metal 9 or metal oxide 10 , non-solvent-assisted casting 11 , and polymer blends 12–15 , but improvements in both conductivity and fuel cell performance have been modest.…”

Section: Introductionmentioning

confidence: 99%

“…Electric field alignment has been explored by incorporating metal 9 or metal oxide 10 , non-solvent-assisted casting 11 , and polymer blends 12–15 , but improvements in both conductivity and fuel cell performance have been modest. In the case of magnetic field alignment, this has been carried out using materials related only to metal oxides, such as pristine metal oxides 16–18 , coated metal oxide 19 , and other filler deposited with metal oxide 20 . This class of fillers for magnetic alignment are not proton conductive, and thus their incorporation would result in a reduction in ion exchange capacity (IEC), which compromises any gains in proton conductivity through enhancement of TP alignment.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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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.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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“…The proton conductivity of membranes is calculated by the electrochemical impedance spectroscopy (EIS) and can be measured in two directions; i.e., in-plane or through-plane (Tang et al, 2012), by either four-probe or two-probe method. Conductivity (σ) is calculated using the following equation (Eq.…”

Section: Membrane Proton Conductivity Measurementmentioning

confidence: 99%

Advanced nanocomposite membranes for fuel cell applications: a comprehensive review

2016

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“…10,11,13 Similarly, a strong magnetic field was shown to align conductive groups conjugated with magnetically active moieties in a hydrocarbon-based ionomer, 14,15 as well as Nafion 16 and a similar perfluorinated ionomer. 17 Nafion channels were also shown to preferentially orient next to interfaces, which enhances conductivity in ultrathin Nafion films on solid substrates. 18,19 Unfortunately, this interfacial effect barely extends over a few tens of nanometers, i.e., distances commensurate with the bundle width.…”

Section: Introductionmentioning

confidence: 95%

“…Nevertheless, certain stimuli were found to promote channel orientation in Nafion and other ion-conducting materials and, correspondingly, increase TP conductivity. For instance, similar to TP alignment of conductive particles in an insulating matrix, , an electric field may promote conductive channel alignment in ionomers, including Nafion, − which works best when the field is applied to a solution during membrane casting. ,, Similarly, a strong magnetic field was shown to align conductive groups conjugated with magnetically active moieties in a hydrocarbon-based ionomer, , as well as Nafion and a similar perfluorinated ionomer . Nafion channels were also shown to preferentially orient next to interfaces, which enhances conductivity in ultrathin Nafion films on solid substrates. , Unfortunately, this interfacial effect barely extends over a few tens of nanometers, i.e., distances commensurate with the bundle width.…”

Section: Introductionmentioning

confidence: 96%

Electrospun Ion-Conducting Composite Membrane with Buckling-Induced Anisotropic Through-Plane Conductivity

Odess

Cohen

et al. 2021

ACS Appl. Mater. Interfaces

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Fuel cell (FC) is an attractive green alternative for today's fuel combustion systems. In common FCs, a polymer electrolyte membrane selectively conducts protons but blocks the passage of electrons and fuel. Nafion, the current benchmark membrane material, has a superior conductivity owing to unique morphology comprising randomly oriented elongated ionic nanochannels within its Teflon-like matrix. Channel orientation enhances Nafion conductivity, yet there has been no facile method to induce a stable alignment in the desired through-plane (TP) direction. Here, we report an approach based on dual electrospun Nafion-PVDF nanofiber composites that yields a stable TP alignment. It utilizes extreme thinness and strong inherent orientation within electrospun nanofibers, which is readily converted to TP alignment by plunging an electrospun nanofiber mat into a thin slit, resulting in nanofiber buckling and subsequent consolidation. Using TEM and SAXS, we demonstrate a pronounced and sustained TP ion channel orientation in prepared membranes, yielding a highly anisotropic swelling and conductivity exceeding that of bulk Nafion when normalized to Nafion content. The analysis also highlights the importance of PVDF as a stabilizing component, preserving orientation upon annealing, while a similarly prepared pure Nafion membrane loses anisotropy. The approach holds potential to advance the FC technology by overcoming current limitations of ionomeric membranes.

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Perfluorosulfonate ionomer membranes with improved through-plane proton conductivity fabricated under magnetic field

Cited by 24 publications

References 36 publications

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

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

Advanced nanocomposite membranes for fuel cell applications: a comprehensive review

Electrospun Ion-Conducting Composite Membrane with Buckling-Induced Anisotropic Through-Plane Conductivity

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