Perfluorosulfonic acid ionomer – silica composite membranes prepared using hyperbranched polyethoxysiloxane for polymer electrolyte membrane fuel cells (original) (raw)
Related papers
International Journal of Hydrogen Energy, 2011
Organiceinorganic hybrid proton exchange membranes were prepared from poly(vinyl alcohol) (PVA) and various amounts of nanoporous silica containing phenyl sulfonic acid groups. These hybrid membranes were prepared via co-condensation of functionalized nanoporous SBA-15 (SBA-ph-SO 3 H) as hydrophilic inorganic modifier, glutaraldehyde (GLA) as cross-linking agent in a PVA matrix. These membranes were characterized for their morphology, thermal stability, electrochemical and physicochemical properties using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and water uptake studies. The SBA-ph-SO 3 H/PVA composite membranes have a higher water retention and thermal stability than that of Nafion 117, perhaps because of responsibility of both acidic groups and nanoporous structure of silica additive. This work demonstrates the promising potential of new composite membranes for the development of high-performance and high-stability PEM fuel cells with improved proton conductivity.
Polysulfone ionomers for proton-conducting fuel cell membranes
Electrochimica Acta, 2005
Polysulfones and polyphenylsulfones having pendant phenyl groups with sulfonic acid units have been prepared by lithiation of the respective polymer, followed by reaction with 2-sulfobenzoic acid cyclic anhydride. The resulting ionomers were cast into membranes and properties such as thermal stability, ion-exchange capacity, water sorption and proton conductivity were evaluated. These membranes proved to have a high thermal stability, with a decomposition temperature between 300 and 350 • C, and a high proton conductivity, 60 mS/cm at 70 • C for a polyphenylsulfone with 0.9 sulfonic acid group per repeating unit measured at 100% relative humidity. Moreover, some of the membranes endured immersion in water at temperatures ranging from 20 to 150 • C without swelling extensively, and therefore kept their mechanical stability under these conditions. It was also shown that these membranes retained a high conductivity up to 150 • C under humidifying conditions. The combination of properties make these membranes potential candidates for fuel cells operating at temperatures above 100 • C.
Membranes
Series of partially fluorinated sulfonated poly(arylene ether)s were synthesized through nucleophilic substitution polycondensation from three types of diols and superhydrophobic tetra-trifluoromethyl-substituted difluoro monomers with postsulfonation to obtain densely sulfonated ionomers. The membranes had similar ion exchange capacities of 2.92 ± 0.20 mmol g−1 and favorable mechanical properties (Young’s moduli of 1.60–1.83 GPa). The membranes exhibited considerable dimensional stability (43.1–122.3% change in area and 42.1–61.5% change in thickness at 80 °C) and oxidative stability (~55.5%). The proton conductivity of the membranes, higher (174.3–301.8 mS cm−1) than that of Nafion 211 (123.8 mS cm−1), was the percent conducting volume corresponding to the water uptake. The membranes were observed to comprise isolated to tailed ionic clusters of size 15–45 nm and 3–8 nm, respectively, in transmission electron microscopy images. A fuel cell containing one such material exhibited hi...
Polymer, 2006
Sulfonated poly(arylene ether ether ketone ketone) (SPAEEKK) copolymer containing pendant sulfonic acid group (sulfonic acid content (SC) ¼ 0.67) was synthesized from commercially available monomers such as sodium 6,7-dihydroxy-2-naphthalenesulfonate (DHNS), 1,3bis(4-fluorobenzoyl)-benzene (BFBB), and hexafluorobisphenol A (6F-BPA). SPAEEKK/silica hybrid membranes were prepared using the solegel process under acidic conditions. The SPAEEKK/silica hybrid membranes were fabricated with different silica contents and the membranes were modified to achieve improved proton conductivity incorporating PeOH groups (H 3 PO 4 treatment).
Journal of Membrane Science, 2001
Sulfonation of polysulfone strongly affects both protonic conductivity and lifetime of composite polyelectrolytes. Viscosimetric comparisons showed the effect of the sulfonating agent. Indeed, chlorosulfonic acid leads to chain cleavage while its trimethyl silyl ester does not affect the polymer backbone. Sampling aliquots allowed the sulfonation yield to be followed by 1 H NMR. From this study, one might infer that the conversion should not exceed 70% of the theoretical yield. Viscosimetric measurements performed on the same aliquots demonstrated that, even after 72 h reaction time, chain cleavage did not occur. Filling of sulfonated polysulfone with 8% of phosphatoantimonic acid resulted in a conductivity trebling 0.06 versus 0.02 S cm −1 at 80 • C and 98% of relative humidity (RH). Electrochemical performances, thermo-mechanical stability and low cost make this composite membrane an attractive material for proton exchange membrane fuel cell (PEMFC).
Materials Research Bulletin, 2017
The present work is an attempt to improve the usseful properties of sulfonated polyphenylene oxide in order to obtain a proton exchange membrane (PEM) for proton exchange membrane fuel cells(PEMFC). Formation of siloxane compounds inside the polymer matrix through an in situ sol-gel process improves properties of the composite membrane: water retention, tensile strength and dimensional stability of the membrane. The presence of the silicone atoms inside the polymer matrix is highlited in the X-ray fluorescence spectra. Parameters related to water absorbtion and proton transport inside the membrane such as: water uptake, hydration number (l), dimensional expansion by hydration, ion exchange capacity and sulfonation degree show an optimization of the composite membrane compared to the polymeric one. Furthermore, the tensile strength of the composite membranes is better than the polymeric one when both samples are fully hydrated.
High Conductivity Perfluorosulfonic Acid Nanofiber Composite Fuel‐Cell Membranes
…, 2010
There is a need for polymeric hydrogen/air fuel-cell membranes that can efficiently conduct protons at moderate to high temperatures for wet and dry gas feeds. The US Department of Energy (DOE), for example, set an exceedingly stringent preliminary target for membrane conductivity, 0.10 S cm À1 at 120 8C and 50 % relative humidity (RH). Herein, we describe the fabrication and basic properties of one membrane that exhibits outstanding proton conductivity over a wide range of humidity conditions at temperatures of 80 8C and 120 8C. The membrane is based on a nanofiber network composite design with precise topological separation of the proton transporting and mechanically reinforcing polymer components. This desirable morphology is created via electrospinning, an electrostatic fiber processing technique that has been known for more than one hundred years and underwent a renaissance in the early 1990s, mainly due to the work of Reneker et al. The use of electrospinning for membrane and porous filter fabrication is not yet widespread, but interest in this technique is growing. Nanofiber air filters with highly desirable retention characteristics have recently been commercialized. Electrospinning of ionic polymers, on the other hand, is quite new and the data on these systems are very scarce.
Chinese Journal of Polymer Science, 2014
New siloxane and sulfone containing poly(benzimidazole/sulfone/siloxane/amide) (PBSSA) has been prepared for the formation of hybrid membranes (PBSSA/PS-S/SiNPs) with sulfonated polystyrene (PS-S) and 0.1 wt%−2 wt% silica nanoparticles (SiNPs). Field emission scanning electron micrographs showed good dispersion of filler, formation of dense nanoporous honeycomb like structure and uniform ionic pathway in these hybrids. The porous membrane structure was responsible for the fine water retention capability and higher proton conductivity of the new hybrids. Increasing the amount of nanoparticles from 0.1 wt% to 2 wt% increased the tensile stress of acid doped PBSSA/PS-S/SiNPs nanocomposites from 65.7 MPa to 68.5 MPa. A relationship between nanofiller loading and thermal stability of the membranes was also experientially studied, as the glass transition temperature of phosphoric acid doped PBSSA/PS-S/SiNPs nanocomposites increased from 207 °C to 215 °C. The membranes also had higher ion exchange capacity (IEC) around 2.01 mmol/g to 3.01 mmol/g. The novel membranes with high IEC value achieved high proton conductivity of 1.10−2.34 S/cm in a wide range of humidity values at 80 °C which was higher than that of perfluorinated Nafion ® 117 membrane (1.1 × 10 −1 S/cm) at 80 °C (94% RH). A H 2 /O 2 fuel cell using the PBSSA/PS-S/SiNP 2 (IEC 3.01 mmol/g) showed better performance than that of Nafion ® 117 at 40 °C and 30% RH.
Journal of Nanostructure in Chemistry, 2014
Organic-inorganic nanocomposite membranes of poly(vinyl alcohol) (PVA) and nanoporous silica containing sulfonic acid groups are synthesized in order to increase the proton conductivity, water retention and thermal stability of membrane. The cross-linked PVA/ SBA-15-propyl-SO 3 H nanocomposite membrane was prepared by solution casting method. Infrared spectroscopy and scanning electron microscopy are used to characterize and confirm the structure of PVA and the cross-linked membranes. The impedance spectroscopy, water uptake and thermal stability of membranes are investigated to confirm their applicability in fuel cells. It was found that the cross-linked PVA/SBA-15-propyl-SO 3 H nanocomposite membrane appears to be a good candidate for using in PEM fuel cell.
New highly phosphonated polysulfone membranes for PEM fuel cells
Journal of Membrane Science, 2010
This paper reports the development and characterization of phosphonated poly(arylene ether sulfone) polymer electrolytes for direct methanol fuel cells. The synthesis of phosphonated polysulfone was performed by a post-phosphonation method via chloromethylation of the polysulfone backbone followed by phosphonation utilizing the Michaels-Arbuzov reaction. High degree of phosphonation up to 150% was achieved without crosslinking side reactions. The obtained membranes/polymers in the ester form were hydrolyzed to the corresponding phosphonic acid by refluxing in aqueous hydrochloric acid. The modified polymers were characterized by nuclear magnetic resonance, infrared spectroscopy, ion exchange capacity, differential scanning calorimetry and thermal gravity analysis. The high level of phosphonic acid content 150% led to high water uptake level 52 wt% which is necessary to reach high proton conductivity values. The synthesized membranes with the highest phosphonic acid content 150% reached 12 mS/cm at 100 • C under fully hydrated conditions and showed low methanol crossover (9.12 × 10 −8 cm 2 /s) compared to Nafion 117 membranes. Also, membranes with 150% phosphonic acid content exhibit high thermal stability up to 252 • C under air which entitle them as future candidates for proton exchange membrane fuel cells PEMFCs.