Influence of Sulfonated Graphene Oxide on Sulfonated Polysulfone Membrane for Direct Methanol Fuel Cell

Novel proton exchange membranes consisting of an inorganic filler, namely sulfonated graphene oxide, embedded in sulfonated polysulfone were fabricated. The membrane performance depended on the sulfonated graphene oxide content possessed the functional groups to provide the interfacial interaction with sulfonated polysulfone through ionic channels and blocking effect. The membrane with 3% v/v sulfonated graphene oxide content embedded in the matrix was shown to be suitable for direct methanol fuel cell applications. The membrane exhibited the highest proton conductivity of 4.27?×?10^?3 S cm^?1 which was higher than that of Nafion117. Moreover, the membrane provided the lowest methanol permeability of 3.48?×?10^?7?cm²/s which was lower than that of Nafion117.     

Polymer Electrolyte Membrane Based on Sulfonated Poly(Ether Ketone Ether Sulfone) (S-PEKES) with Low Methanol Permeability for Direct Methanol Fuel Cell Application

Poly(ether ketone ether sulfone), (PEKES), was synthesized by the nucleophilic aromatic substitution polycondensation between bisphenol S and 4,4′-difluorobenzophenone (system A), and between bisphenol S and 4,4′-dichlorobenzophenone (system B). The oxidative stability was characterized by using a Fenton's reagent. S-PEKES membranes show a higher thermal stability than that of Nafion 117 and comparable to that of S-PEEK 150XF. The proton conductivity values of S-PEKES of the highest DS are comparable to those of Nafion 117 and S-PEEK. The methanol permeability of the synthesized and fabricated S-PEKES membrane is lower than that of Nafion 117 by at least an order of magnitude.     

直接甲醇燃料电池用Nafion膜及其改性研究进展

讨论了 Nafion膜在直接甲醇燃料电池中的应用 ,综述了国内外对直接甲醇燃料电池用 Nafion膜改性的最新进展。     

Modified Sulfonated Poly(ether ether ketone) Based Mixed Matrix Membranes for Direct Methanol Fuel Cells

Mixed matrix membranes based on zeolite 4A‐methane sulfonic acid (MSA)‐sulfonated poly(ether ether ketone) (SPEEK) are evaluated as a potential polymer electrolyte membrane (PEM) for direct methanol fuel cells (DMFCs). Ion‐exchange capacity, sorption of water, and water–methanol mixture, proton conductivity, and methanol permeability for the mixed‐matrix membranes have been extensively investigated. The mixed‐matrix membranes are also characterized for their cross‐sectional morphology, mechanical, and thermal properties. DMFCs employing SPEEK‐MSA (20 wt.%) blend, zeolite 4A (4 wt.%)‐SPEEK‐MSA (20 wt.%) mixed matrix membranes deliver peak power densities of 130 and 159 mW cm^–2, respectively; while a peak power density of only 95 mW cm^–2 is obtained for the DMFC employing pristine SPEEK membrane at 70 °C. The results showed that these SPEEK based mixed matrix membranes exhibit higher DMFC performance and lower methanol permeability in comparison to Nafion‐117 membrane.     

Chitosan/titanate Nanotube Hybrid Membrane with Low Methanol Crossover for Direct Methanol Fuel Cells

Titanate nanotubes (TNTs) about 10 nm in diameter and 200–600 nm in length were hydrothermally synthesized, and then incorporated into a chitosan (CS) matrix to fabricate chitosan/titanate nanotube (CS/TNT) hybrid membranes for a direct methanol fuel cell (DMFC). These hybrid membranes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray powder diffraction (XRD), thermogravimetry (TG), and positron annihilation lifetime spectroscopy (PALS). Moreover, their performances, including mechanical strength, water and methanol uptake, methanol permeability, and proton conductivity were determined. SEM results demonstrated that TNTs dispersed homogeneously in the hybrid membranes. Mechanical strength and TG measurements demonstrated that the mechanical and thermal stability of CS/TNT hybrid membranes were much higher than those of pure chitosan membranes. PALS analysis revealed that the fractional free volume (FFV) of CS/TNT hybrid membranes increased with the incorporation of TNTs and, thus, resulting in the reduction of methanol crossover. In all as‐prepared membranes, the hybrid membrane containing 15 wt % TNTs exhibited the highest mechanical strength of 85.0 MPa, low methanol permeability of 0.497 · 10^–6 cm²·s^–1, and proton conductivity of 0.0151 S·cm^–1, which had the potential for DMFC applications.     

Composite Proton Exchange Membranes of Sulfonated Poly(ether ketone ether sulfone) (S-PEKES) and Molecular Sieve With High Mechanical Strength for Direct Methanol Fuel Cell

Composite proton exchange membranes are prepared by solvent casting via the incorporation of molecular sieves 3A, 4A, and 5A into the sulfonated poly(ether ketone ether sulfone) (S-PEKES) at the sulfonation degree of 0.66, with varying the ratio at of 3%, 6%, 9%, and 12% v/v. The influences of type and amount of the molecular sieves on the proton conductivity, methanol permeability, structural, thermal, and mechanical stabilities of the membranes are investigated. The composite membranes are characterized by FTIR, TGA, LCR meter, and GC techniques. All properties of the composite membrane are compared with the pristine S-PEKES and Nafion 117 membrane.     

Evaluation of Sulfonated Poly(Ether Ether Ketone) Silicotungstic Acid Composite Membranes for Fuel Cell Applications

Fuel cells have received much attention for clean power generation for transportation, portable power systems, etc. Composite membranes are better than the homopolymeric membranes, as their properties can be altered by varying the composition.

In our present study, five samples of sulfonated poly(ether ether ketone) (SPEEK)/silicotungstic acid (SWA) composite membranes were prepared. The molecular interactions of the composite membranes were characterized by FTIR and XRD techniques. The ion exchange capacity (IEC) was studied. The thermal suitability was found to be excellent as confirmed by TGA. SEM analysis revealed uniform distribution of the hetero poly acid (HPA) in the composite membranes. The protonic conductivity determined by impedance spectroscopy was found to be in the order of 10^?3 S/cm. The change in the mechanical properties of the composite membranes was observed by Universal Testing Machine (UTM).

Overall, the composite membranes proved to be an excellent candidate for fuel cell applications.     

Synthesis and Characterization of Sulfonated Cardo Poly(Arylene Ether Sulfone)s for Fuel Cell Proton Exchange Membrane Application

Sulfonated cardo poly(arylene ether sulfone)s ( SPPA ‐ PES ) with various degrees of sulfonation (DS) were prepared by post‐sulfonation of synthesized phenolphthalein anilide ( PPA ; N‐phenyl‐3,3′‐bis(4‐hydroxyphenyl)‐1‐isobenzopyrolidone) poly(arylene ether sulfone)s ( PPA ‐ PES ) by using concentrated sulfuric acid. PPA ‐ PES copolymers were synthesized by direct polycondensation of PPA with bis‐(4‐fluorophenyl)‐sulfone and 4,4′‐sulfonyldiphenol. The DS was varied with different mole ratios of PPA (24, 30, 40, 50 mol.%) in the polymer. The structure of the resulting SPPA ‐ PES copolymers and the different contents of the sulfonated unit were studied by Fourier transform infrared (FT‐IR) spectroscopy, ¹H NMR spectroscopy, and thermogravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymer with water. The ion exchange capacity (IEC) and proton conductivity of SPPA ‐ PES were evaluated according to the increase of DS. The water uptake (WU) of the resulting SPPA ‐ PES membranes was in the range of 20–72%, compared with 28% for Nafion 211®. The SPPA ‐ PES membranes showed proton conductivities of 23–82 mS cm^–1, compared with 194 mS cm^–1 for Nafion 211®, under 100% relative humidity (RH) at 80 °C.     

Influence of Methanol Crossover on the Fuel Utilization of Passive Direct Methanol Fuel Cell

The effect of methanol crossover on the fuel utilization of a passive direct methanol fuel cell (DMFC) was reported. The results revealed that the Faradaic efficiency decreased from 46.9 to 17.4% when methanol concentration increased from 1.0 to 8.0 mol L^–1 at the lower current density 11.1 mA cm^–2. However, the Faradaic efficiency increased from 14.7 to 31.3% when methanol concentration increased from 1.0 to 8.0 mol L^–1 at a higher current density of 44.4 mA cm^–2. On the other hand, although the amount of methanol was increased, the Faradaic efficiency did not change, obviously due to the uniform methanol crossover and methanol diffusion at the same methanol concentration and constant current.     

Preparation and Characterization of Perfluorosulfonate‐Free Phosphosilicate Glass‐Based Composite Proton‐Exchange Membrane

Based on hydrothermally treated phosphosilicate (SiO₂–P₂O₅) glass and sulfonated poly(ether ether ketone) (SPEEK) polymer, perfluorosulfonate‐free SiO₂–P₂O₅/SPEEK composite membranes are prepared. The morphology, thermal and mechanical properties, pore structure, proton conductivity, water uptake, as well as the fuel cell performances of the SiO₂–P₂O₅/SPEEK composite membranes are investigated. The SiO₂–P₂O₅/SPEEK composite membranes with proton conductive SiO₂–P₂O₅ glass powders of more than 50 wt.% were determined to be flexible due to the incorporation of the SPEEK polymer component, and it showed proton conductivities of above 10^–2 S cm^–1. A single H₂/O₂ fuel cell was assembled based on the SiO₂–P₂O₅/SPEEK composite membrane, and was found to release a peak power density of 355.6 mW cm^–2 at 68 °C.     

磺化聚酰亚胺质子导电材料的研究进展

由于Nafion膜在工作温度超过90℃的燃料电池中，或者是在直接甲醇燃料电池中的种种不良表现使得燃料电池的应用得到制约，所以发展新型导电聚合物电解质膜就与聚台物燃料电池的发展紧密联系在一起。近些年来这个领域的研究成果包括新的离子聚合物、用于控制形态及保水能力的纳米无机颗粒复合膜，以及碱性聚合物与含氧酸的络合物等。而聚酰亚胺，作为一种耐高温的含氮杂环碱性聚合物，在电解质燃料电池中正表现出广阔的应用前景。     

直接甲醇燃料电池用新型质子交换膜的研究

以聚醚醚酮(PEEK)为原料,浓硫酸为磺化剂制备了不同磺化度的磺化聚醚醚酮(SPEEK)膜,以及磺化聚醚醚酮与聚乙烯醇(PVA)、正硅酸乙酯(TEOS)、磷钨酸的复合膜.分别对膜的电导率、阻醇性能和吸水率进行了研究.随着SPEEK膜磺化度的增大,膜的电导率有所提高,然而甲醇渗透系数也增大,膜的机械强度明显降低.SPEEK膜的吸水率低于Nafion 115膜,而PVA膜的吸水率则过高.     

Sulphonated Tetramethyl Poly(ether ether ketone)/Epoxy/Sulphonated Phenol Novolac Semi‐IPN Membranes for Direct Methanol Fuel Cells

The sulphonated phenol novolac (PNBS) which was used as a curing agent of epoxy was synthesised from phenol novolac (PN) and 1, 4‐butane sultone and confirmed by FTIR and ¹H NMR. The degree of sulphonation (DS) in PNBS was calculated by ¹H NMR. The semi‐IPN membranes composed of sulphonated tetramethyl poly(ether ether ketone) (STMPEEK) (the value of ion exchange capacity is 2.01 meq g^–1), epoxy (TMBP) and PNBS were successfully prepared. The semi‐IPN membranes showed high thermal properties which were measured by differential scanning calorimeter (DSC) and thermogravimetric analyses (TGA). With the introduction of the cross‐linked TMBP/PNBS, the mechanical properties, dimensional stability, methanol resistance and oxidative stability of the membranes were improved in comparison to the pristine STMPEEK membrane. Although the proton conductivities of the semi‐IPN membranes were lower than those of the pristine STMPEEK membrane, the higher selectivity defined as the ratio of the proton conductivity to methanol permeability was obtained from the STMPEEK/TMBP/PNBS‐14 semi‐IPN membrane. The results indicated that the semi‐IPN membranes could be promising candidates for usage as proton exchange membranes in direct methanol fuel cells (DMFCs).     

直接甲醇燃料电池技术及应用

本文回顾了直接甲醇燃料电池（ＤＭＦＣ）的研究开发历史,系统阐述了ＤＭＦＣ系统中电催化剂选择与设计基本原则、电解质膜材料与甲醇渗透的关系。分析了电池工作温度、工作压力和甲醇进料方式对ＤＭＦＣ电化学性能的影响。     

Empirical Model Equations for the Direct Methanol Fuel Cell DMFCs

Empirical model equations, proposed for polymer electrolyte fuel cells, are used to predict the cell voltage vs. current density response of a liquid feed direct methanol fuel cell. The model equations are validated against experimental data for a small-scale fuel cell over a wide range of methanol concentration and temperatures. A new empirical equation is presented which is able to predict the voltage response of liquid feed direct methanol fuel cells over a wide range of operating conditions and even in the case of very low current densities caused by, for example, the use of dilute methanol solutions or low cell temperatures.     

Enhanced Proton Conductivity of Sulfonated Poly(ether ether ketone) Membrane Embedded by Dopamine‐Modified Nanotubes for Proton Exchange Membrane Fuel Cell

Design and fabrication of alternative proton exchange membrane (PEM) with high proton conductivity is crucial to the commercial application of PEM fuel cell. Inspired by the bioadhesion principle, dopamine‐modified halloysite nanotubes (DHNTs) bearing –NH₂ and –NH– groups are facilely synthesized by directly immersing natural halloysite nanotubes (HNTs) into dopamine aqueous solution under mild conditions. DHNTs are then embedded into sulfonated poly(ether ether ketone) (SPEEK) matrix to prepare hybrid membranes. HNTs‐filled hybrid membranes are prepared for comparison. The microstructure and physicochemical properties of the membranes are extensively investigated. Fourier transform infrared analysis implies that ordered acid–base pairs (e.g., –S–O^–…⁺H–HN–, –S–O^–…⁺H–N–) are formed at SPEEK–DHNT interface through strong electrostatic interaction. In such a way, continuous surface‐induced ion‐channels emerge along DHNTs. Although the incorporation of DHNTs reduces the channel size, water uptake, and area swelling of the hybrid membranes, which in turn would reduce the vehicle‐type proton transfer, the acid–base pairs create continuous pathways for fast proton transfer with low energy barrier via Grotthuss mechanism. Consequently, DHNT‐filled hybrid membrane with 15% DHNTs achieves a 30% increase in proton conductivity and a 52% increase in peak power density of single cell when compared with SPEEK control membrane, particularly.     

直接甲醇燃料电池钯基催化剂研究进展

直接甲醇燃料电池(DMFC)阳极催化剂是直接甲醇燃料电池的关键材料之一。由于钯的价格便宜、储量丰富、在碱性条件下活性较高,成为取代铂作为DMFC的潜在的阳极催化剂。着重介绍了近年来钯基阳极催化剂在碱性条件下对甲醇的电氧化的研究进展,展望了其发展前景。     

Modeling Flow Distribution for Internally Manifolded Direct Methanol Fuel Cell Stacks

A model is presented for the liquid feed direct methanol fuel cell, which describes the hydraulic behavior of an internally manifolded cell stack. The model is based on the homogeneous two‐phase flow theory and mass conservation equation. The model predicts the pressure drop behavior of an individual fuel cell, and is used to calculate flow distribution through fuel cell stack internal manifolds. The flow distribution of the two‐phase fluids in the anode and the cathode chambers is predicted as a function of cell operating parameters. An iterative numerical scheme is used to solve the differential equations for longitudinal momentum and continuity.     

A Pumpless Methanol Feeding Method for Application in Direct Methanol Fuel Cell Systems

This paper presents a simple and reliable pumpless methanol feeding (PLMF) method for application in direct methanol fuel cell (DMFC) systems. The primary feature and advantage of the PLMF is as follows: it employs an approach that allows the cathode gas pressure to be connected with a fuel container for supplying the methanol fuel into the anode fuel loop, instead of using any feeding pump or other specially designed apparatuses. The PLMF has been used in a portable 25 W DMFC system and realised feeding methanol in real time for meeting the requirements of the system. The PLMF method not only is suitable for the DMFC system, but also can be used in other liquid‐feeding fuel cell systems.     

基团法估算磺化聚苯醚的溶解度参数

以氯磺酸为磺化剂制备了一系列不同磺化度的磺化聚苯醚（SPPO）。采用基团贡献法估算出了聚苯醚（PPO）及SPPO的溶解度参数值，随着磺化度的增加，溶解度参数逐渐增加，估算的结果与SPPO在不同溶剂中的溶解行为基本吻合。