Coating and lamination of Nafion117 with partially sulfonated PVdF for low methanol crossover in DMFC applications (original) (raw)
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The surface of Nafion 117 membrane was modified by dip-coating of a blend of polybenzimidazole (PBI) and partially sulfonated polyvinylidinefluoride-co-hfp (SPVDF-co- HFP) polymer without any significant change in the thickness of the membrane. The dipcoated membranes were characterized by FTIR spectroscopy, thermogravimetry and rheology; ion exchange capacity (IEC), proton conductivity and methanol permeability were also measured to find the suitability of these membranes in the direct methanol fuel cell (DMFC), especially keeping in view with a reduced methanol crossover and improved electrical efficiency. The IEC and proton conductivity of the membranes were observed to be lower than pristine Nafion 117 membrane. On the other hand, the methanol permeability of coated membranes was found to be very less than the pristine Nafion 117 membrane. Although, a very thin coat of the blends of PBI and SPVdF-co-HFP was applied on Nafion117, the dynamic rheological studies indicated that the glass transition temperature of nafion117 shifted to a higher temperature, leading to higher stability of coated membranes at higher temperature in comparison to the stability of Nafion. The high thermal stability of the coated membranes compared to Nafion was also corroborated from the thermogravimetric analysis. All these results indicated that the coated Nafion117 membrane could be electrically efficient at high temperature for DMFC applications. From the DMFC performance test, it was observed that the Nafion 117 membrane coated with 70:30 PBI and SPVDF-co-HFP showed the best electrical performance (39mW/cm2 at 0.2 V) at the temperature of 90 °C, whereas for pristine Nafion 117 membrane, the maximum electrical performance of the DMFC was observed to be 36 mW/cm2 at the same voltage and at 60 °C.
A coated Nafion membrane with a PVdF copolymer/Nafion blend for direct methanol fuel cells (DMFCs)
Solid State Ionics, 2005
To enhance the compatibility between electrode and membrane and also reduce methanol crossover from anode to cathode in direct methanol fuel cells, a Nafion membrane coated with a PVdF copolymer/Nafion blend has been prepared and characterized. This coated Nafion shows reduced methanol crossover and an enhancement in cell performance due to its improved compatibility with the electrode compared to that of native Nafion. D
European Polymer Journal, 2008
Poly-(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP)/Nafion ionomer/aluminum oxy hydroxide nanocomposite membranes were prepared by phase inversion technique. The resultant membranes were subjected to protonic conductivity, methanol permeability, infra-red and thermogravimmetric analysis. The infra-red spectroscopic measurements revealed the presence of sulfonic acid groups in the composite membranes. The thermal stability and ionic conductivity of the polymer membranes have been greatly varied upon the addition of AlO[OH] n . Although the PVDF-HFP/Nafion/AlO[OH] n composite membranes have moderate protonic conductivity it has lower methanol permeability and may be considered as a candidate for DMFC applications.
Characteristics of PVdF copolymer/Nafion blend membrane for direct methanol fuel cell (DMFC)
Electrochimica Acta, 2004
For direct methanol fuel cell, blends of vinylidene fluoride-hexafluoropropylene copolymer (P(VdF-co-HFP)) and Nafion were prepared the different equivalent weight of Nafion. The investigations of the blend morphology were performed by means of permeability test, uptake measurement, differential-scanning calorimetry (DSC), and scanning electron microscopy.
Applied Energy, 2014
Fabrication of low cost sulfonated polystyrene/PVdF-co-HFP/Nafion semi-IPN PEM. Enhancement of water uptake value and ion exchange capacity compared to Nafion-117. A maximum current density of 120 mA cm À2 at 0.2 V was obtained. A cell efficiency of 24 mW cm À2 at 60°C was obtained while using air at cathode. Enhanced proton conductivity over Nafion-117 was recorded. g r a p h i c a l a b s t r a c t a b s t r a c t Sodium salt of sulfonated styrene (SS) was polymerized in situ within the polymeric blend of PVdF-co-HFP/Nafion. The electrical efficiency of this cross-linked semi interpenetrating network membranes were evaluated for its potential application as a polymer electrolyte membrane in direct methanol fuel cell (DMFC). The characteristic aromatic peaks obtained in the FT-IR spectra confirmed the successful incorporation of SS within the polymeric blend. X-ray diffraction analyses were conducted to determine the presence of crystalline and amorphous domains within the structure of the blend membrane. Water uptake measurements at room temperature indicate that above a threshold value of 20 wt% of incorporated SS (S-20), water uptake of the semi-IPN membranes increases up to 24%, with an IEC value equal to Nafion, i.e. 0.8 meq g À1 . The maximum current density was recorded to be 120 mA cm À2 at 0.2 V, with a cell efficiency (power density) of 24 mW cm À2 at 60°C. In addition, proton conductivity and methanol permeability test results indicate that the prepared membrane S-20 is comparable to that of Nafion-117 membrane.
RSC Adv., 2015
was incorporated into the blend of sulfonated-PVdF-co-HFP/Nafion using NMP (1-methyl-2pyrrolidone) as a common solvent with the aim to develop an alternate membrane to be used in a single cell direct methanol fuel cell (DMFC). Furthermore, the synthesized nano-composite membranes were subjected to different tests such as FTIR, XRD, water uptake, swelling, IEC (ion exchange capacity), proton conductivity and methanol crossover. The water uptake results indicated that with an increase in the nano-Al 2 O 3 content (up to 5% w/w) in the blend, the water uptake of the nanocomposite matrix rapidly increased up to 34.8%. Sample S-5 composed of 5% (w/w) Al 2 O 3 exhibited comparable proton conductivity/IEC, low methanol permeability and high membrane selectivity over the corresponding Nafion-117 membrane. In addition, the prospective nanocomposite membrane also exhibited comparable mechanical stability. Moreover, the maximum current density at 0.2 V in a single cell DMFC, which was operated with atmospheric air (without preheating/humidification) at the cathode, was recorded as 285 mA cm À2 and 270 mA cm À2 at 90 C and 110 C, respectively. Comparing the power densities of the single cell fitted with the membrane of Nafion-1 17 (28 mW cm À2 ) and blend of sulfonated-PVdF-co-HFP and Nafion (32 mW cm À2 ), the single cell with the composite membrane S-5 showed an optimum power density (57 mW cm À2 ) at +0.2 V at a high temperature of 90-110 C. These results indicate that the composite membrane could effectively reduce the anhydrous conditions at high operating temperatures.
Journal of Membrane Science, 2018
In the present work, three kinds of sulfonated poly(arylene ether ketones) (SPAEKs) with different structures are introduced into Nafion as blending modifiers to enhance the properties of Nafion, especially methanol resistance. Characterizations such as transmission electron microscope (TEM), proton conductivity, methanol crossover, and single cell performance, are carried out to evaluate these composite membranes (SPAEK@Nafion) as prepared. Besides, recast Nafion membrane is prepared and characterized for comparison via the same method. By investigating the microstructure of SPAEK@Nafion membranes, p-BPAF@Nafion membrane is found to have the most homogeneous distribution and Nafion-like phase separation among these membranes. The pendent sulfobutyl side-chain and fluorinated main chain of p-BPAF make it most similar structure with Nafion among three modifiers, and such Nafion-liked structure provides p-BPAF a good compatibility with Nafion, which can facilitate its enhancement for Nafion. Consequently,
Membranes
Nafion, a perfluorosulfonic acid proton exchange membrane (PEM), has been widely used in direct methanol fuel cells (DMFCs) to serve as a proton carrier, methanol barrier, and separator for the anode and cathode. A significant drawback of Nafion in DMFC applications is the high anode-to-cathode methanol fuel permeability that results in over 40% fuel waste. Therefore, the development of a new membrane with lower permeability while retaining the high proton conductivity and other inherent properties of Nafion is greatly desired. In light of these considerations, this paper discusses the research findings on developing Nafion-based membranes for DMFC. Several aspects of the DMFC membrane are also presented, including functional requirements, transport mechanisms, and preparation strategies. More importantly, the effect of the various modification approaches on the performance of the Nafion membrane is highlighted. These include the incorporation of inorganic fillers, carbon nanomateri...
Methanol permeability and properties of DMFC membranes based on sulfonated PEEK/PVDF blends
Journal of Applied Polymer Science, 2006
Proton exchange membranes for a direct methanol fuel cell were prepared by blending poly(vinylidene fluoride) [PVDF] with sulfonated poly(etheretherketone) [SPEEK]. The effects of PVDF content on methanol permeability in the blend membranes were investigated by using a diffusion cell and gas chromatography technique. The thermal resistance and proton conductivity of the membranes were also determined by using a thermal gravimetric analysis (TGA) and an impedance analysis technique, respectively. It was found that methanol permeability in the blend membranes decreased with PVDF content at the expense of proton conductivity. The methanol permeability values of the blend membranes are much lower than that of Nafion 115, whereas proton conductivities of the membranes are comparable to that of Nafion. The thermal stability of these blend membranes are above 2508C which is sufficiently high for use in DMFC.