Small-angle X-ray and neutron scattering study of Nafion-SiO2 hybrid membranes prepared in different solvent media

Dresch, Mauro André; Matos, Bruno R.; Fonseca, Fábio C.; Santiago, Elisabete I.; Lanfredi, Alexandre J. C.; Balog, Sandor

doi:10.1016/j.jpowsour.2014.10.072

Cited by 19 publications

(17 citation statements)

References 29 publications

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“…This means that the larger, more well‐defined SiO 2 nanoclusters exist in the amorphous domains of the Nafion, which brings into the question the mechanism by which vanadium crossover is reduced in membranes that contain the SiO 2 phase, both solution‐cast membranes and ones created via sol–gel chemistry. The results of this study are consistent with recent literature, where Dresch et al observed that the growth of silica particles occurred in both the ionic and nonionic domains of Nafion and was dependent on the solvent media in which the sol–gel reaction was performed. Furthermore, regardless of where the SiO 2 phase resides in the sol–gel hybrid membranes, one possible explanation for the reduced crossover is a decrease in the chain dynamics of the Nafion with the introduction of the SiO 2 nanoparticles, as well as a reduction in chain dynamics with annealing at elevated temperatures (i.e., chain stiffening).…”

Section: Resultssupporting

confidence: 93%

Uncovering the Structure of Nafion–SiO₂ Hybrid Ionomer Membranes for Prospective Large‐Scale Energy Storage Devices

Davis

Kim

Oleshko

et al. 2015

Adv Funct Materials

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4064 wileyonlinelibrary.com thermal stability. [ 5 ] However, Nafi on suffers from low ion selectivity which leads to vanadium crossover in the VRFB and decreases energy effi ciency of the battery over time. [ 3 ] There have been several efforts to combat the low ion selectivity of Nafi on for use as the IEMs in VRFBs. These include creating Nafi on blends with other polymers, [ 6 ] incorporating inorganic fi llers, [ 3,7,8 ] layered composites at interfaces, [9][10][11] as well as synthesizing entirely new classes of Nafi on-inspired membranes. [ 2 ] More specifi cally, sol-gel derived Nafi on-SiO 2 and Nafi on-Si/TiO 2 hybrid membranes were observed to signifi cantly reduce the permeability of vanadium ions and water, while minimally impacting ion exchange capacity (IEC) and proton conductivity, thus improving battery performance. [ 3,7 ] It has been suggested that these fi llers selectively incorporate into the ion-conducting domains of Nafi on, effectively altering (or disrupting) the ion/water transport domains. It is thought that creation of SiO 2 in the ion transport channels acts to reduce vanadium crossover by a "size exclusion" mechanism, impeding the transport of vanadium ions and creating a more ion-selective medium with better crossover resistance. There have been many studies of this type of Nafi on-SiO 2 nanocomposite using infrared [12][13][14][15][16][17] and/or nuclear magnetic resonance (NMR) [ 14,15,17 ] spectroscopy to identify the appropriate mechanism and gain a deeper understanding of the local environment of the SiO 2 and Nafi on phases. These spectroscopic investigations have provided great insight into the local interactions of the inorganic nanoparticles and the Nafi on; however, there is limited information on the nanostructure of these Nafi on-SiO 2 composite membranes.Recently, Ladewig et al. [ 18 ] published a structural characterization study of Nafi on-SiO 2 nanocomposite membranes created using this sol-gel chemistry approach. They employed both small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) to resolve the structure of the ionic domains in the Nafi on composite membranes. While little difference was observed between the X-ray scattering curves of the neat and modifi ed Nafi on, SANS showed a broadening and reduction in intensity of the ionomer peak, as well as a slight shift in the ionomer peak position to higher q (i.e., reduction in the d-spacing of this correlation peak, which can be indicative of Nafi on nanocomposite membranes are attractive candidates for the ion conducting phase in energy storage devices such as vanadium redox fl ow batteries. Herein, vanadium crossover and Nafi on-SiO 2 nanostructure are quantifi ed in a series of hybrid membranes created via solution-casting Nafi on fi lms with discrete SiO 2 nanoparticles, as well as membranes created using an in situ silica sol-gel condensation process. The crossover of vanadium ions is suppressed in all Nafi on membranes with the SiO 2 inorganic phase when compared to unannealed, neat N...

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Section: Resultssupporting

confidence: 93%

Uncovering the Structure of Nafion–SiO₂ Hybrid Ionomer Membranes for Prospective Large‐Scale Energy Storage Devices

Davis

Kim

Oleshko

et al. 2015

Adv Funct Materials

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“…Similar results were obtained on SAXS and SANS analyses of Naon®/SG-derived silicon oxide phase, obtained either by membrane casting or by in situ SG reaction. 13,15,18,19 Concerning the intensity, shape and position of the ionomer peak, we observe a clear dependence with the SG content. A zoom of the ionomer peaks is presented in the inset of Fig.…”

Section: Impact Of the Sg Phase On The Host Membrane Nanostructurementioning

confidence: 69%

“…The hybridization strategy, however, can provide better control over the nanostructure and functional properties. 12 To name a few, one can cite: (i) an improvement of water retention with hygroscopic particles as ZrP, SiO 2 , TiO 2 , ZrO 2 (precipitated within pre-formed PFSA and sPEEK membranes or in the polymer dispersion 13,14 ), (ii) an enhancement of the mechanical properties with SiO 2 llers [15][16][17][18] for PEMPC, (iii) a reduction of vanadium crossover for vanadium redox ow batteries (again SiO 2 llers), 19 (iv) or a mitigation of the chemical degradation (cerium-NPs). 20 In addition, the aforementioned issues like the dispersion or elution of llers/nanocharges can be overcome if a SG network is grown in situ in a host ionomer membrane instead of dispersing inorganic particles into an ionomer solution previous to membrane casting.…”

Section: Introductionmentioning

confidence: 99%

Unveiling the multiscale morphology of chemically stabilized proton exchange membranes for fuel cells by means of Fourier and real space studies

et al. 2021

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“…These challenges have prompted the development of membranes able to operate at elevated temperatures (>100 °C) . High temperature proton exchange membranes (HTPEMs) improve the sluggish kinetics of the oxygen reduction reaction (ORR), increase the tolerance to impurities in reformed fuels, simplify the management of water and temperature, make humidification and cooling units unnecessary due to their independence from water for proton transport, and decrease the fabrication and operating costs of the fuel cells dramatically …”

Section: High‐temperature Pemsmentioning

confidence: 99%

Non‐Fluorinated Polymer Composite Proton Exchange Membranes for Fuel Cell Applications – A Review

2019

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The critical component of a proton exchange membrane fuel cell (PEMFC) system is the proton exchange membrane (PEM). Perfluorosulfonic acid membranes such as Nafion are currently used for PEMFCs in industry, despite suffering from reduced proton conductivity due to dehydration at higher temperatures. However, operating at temperatures below 100 °C leads to cathode flooding, catalyst poisoning by CO, and complex system design with higher cost. Research has concentrated on the membrane material and on preparation methods to achieve high proton conductivity, thermal, mechanical and chemical stability, low fuel crossover and lower cost at high temperatures. Non‐fluorinated polymers are a promising alternative. However, improving the efficiency at higher temperatures has necessitated modifications and the inclusion of inorganic materials in a polymer matrix to form a composite membrane can be an approach to reach the target performance, while still reducing costs. This review focuses on recent research in composite PEMs based on non‐fluorinated polymers. Various inorganic fillers incorporated in the PEM structure are reviewed in terms of their properties and the effect on PEM fuel cell performance. The most reliable polymers and fillers with potential for high temperature proton exchange membranes (HTPEMs) are also discussed.

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Small-angle X-ray and neutron scattering study of Nafion-SiO2 hybrid membranes prepared in different solvent media

Cited by 19 publications

References 29 publications

Uncovering the Structure of Nafion–SiO₂ Hybrid Ionomer Membranes for Prospective Large‐Scale Energy Storage Devices

Uncovering the Structure of Nafion–SiO₂ Hybrid Ionomer Membranes for Prospective Large‐Scale Energy Storage Devices

Unveiling the multiscale morphology of chemically stabilized proton exchange membranes for fuel cells by means of Fourier and real space studies

Non‐Fluorinated Polymer Composite Proton Exchange Membranes for Fuel Cell Applications – A Review

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Small-angle X-ray and neutron scattering study of Nafion-SiO2 hybrid membranes prepared in different solvent media

Cited by 19 publications

References 29 publications

Uncovering the Structure of Nafion–SiO2 Hybrid Ionomer Membranes for Prospective Large‐Scale Energy Storage Devices

Uncovering the Structure of Nafion–SiO2 Hybrid Ionomer Membranes for Prospective Large‐Scale Energy Storage Devices

Unveiling the multiscale morphology of chemically stabilized proton exchange membranes for fuel cells by means of Fourier and real space studies

Non‐Fluorinated Polymer Composite Proton Exchange Membranes for Fuel Cell Applications – A Review

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Uncovering the Structure of Nafion–SiO₂ Hybrid Ionomer Membranes for Prospective Large‐Scale Energy Storage Devices

Uncovering the Structure of Nafion–SiO₂ Hybrid Ionomer Membranes for Prospective Large‐Scale Energy Storage Devices