Papers by Keyword: Anion Exchange Membrane

Abstract: In recent years, the EU policy identified the hydrogen as one of the main energy vectors to support the power production from renewable sources. Coherently, electrolysis is suitable to convert energy in hydrogen with no carbon emission and high purity level. Among the electrolysis technologies, the anion exchange membrane (AEM) seems to be promising for the performance and the development potential at relatively high cost. In the present work, AEM electrolysers, and their technological bottlenecks, have been investigated, in comparison with other electrolysers’ technology such as alkaline water electrolysis and proton exchange membranes. Major efforts and improvements are investigated about innovative materials design and the corresponding novel approach as main focus of the present review. In particular, this work evaluated new materials design studies, to enhance membrane resistance due to working cycles at temperatures close to 80 °C in alkaline environment, avoiding the employment of toxic and expensive compounds, such as fluorinated polymers. Different strategies have been explored, as tailored membranes could be designed as, for example, the inclusion of inorganic nanoparticles or the employment of not-fluorinated copolymers could improve membranes resistance and limit their environmental impact and cost. The comparison among materials’ membrane is actually limited by differences in the environmental conditions in which tests have been conducted, thereafter, this work aims to derive reliable information useful to improve the AEM cell efficiency among long-term working periods.

Abstract: CoNi and FeCoNi hydroxide with narrow voltage distance between oxygen reduction reaction and oxygen evolution reaction was synthetized by electro-deposition in low solvent concentration. 5cm² Membrane electrode assemble (MEA) electrolyzers composed with anion exchange membrane, homogenerated catalyst on both cathode and anode gas diffusion layer (GDL) was fabricated for oxygen electrochemical production from air. The current and yield of binary CoNi device reached up to 466.7mA and 4.4mmol/h (94.7% conversion rate) at 1.2V. The ternary FeCoNi device showed only 0.5% degradation from 394.0mA during 12h. The applicability of oxygen production from air by high performance electrochemical devices was demonstrated.

Abstract: Poly (phthalazinone ether ketone) anion exchange membranes with pyridinium groups (PyPPEK) for vanadium redox flow battery were prepared from chloromethylated poly (phthalazinone ether ketone) and pyridine. The chemical structure of PyPPEK was characterized by using FT-IR spectrum. Compared with quaternary ammonium group containing poly (phthalazinone ether ketone), PyPPEK membrane showed low ion exchange capacity, low swelling ratio and comparable tensile strength. Columbic efficiencies of VRB with anion exchange membranes were higher than that of VRB with Nafion117 membrane. When the ion exchange capacity of PyPPEK membrane was 1.40 mmol·g^-1, energy efficiency of VRB with the membrane was higher than that of VRB with Nafion117 membrane at charge-discharge current densities ranging from 20 mA·cm^-2 to 50 mA·cm^-2.

Abstract: A series of anion exchange membranes (AEMs) based on quaternary poly(ether sulfone)s (QPES) have been successfully prepared through aromatic nucleophilic polymerization, chloromethylation, quaternization and alkalization for alkaline direct methanol fuel cell (ADMFC) applications. The influence of quaternization reagents on properties of the prepared QPES membranes has been discussed in details, including ion exchange capacity (IEC), size change and ionic conductivity. The results indicated that the selection of quaternization reagent is very important. At similar IEC level, the membranes using N,N,N’,N’-tetramethyl-1,3-propanediamine as the quaternization reagent showed relatively high dimensional stability and ionic conductivity.

Abstract: A series of anion exchange membranes based on poly(arylene ether sulfone)s (PAES) have been prepared through condensation polymerization, chloromethylation and quaternization. The membrane using N, N, N’,N’-tetramethylhexyldiamine both as the quaternization and crosslinking reagent had self-crosslinking structure, and their properties have been compared with those using trimethylamie as the quaternization reagent, including ion exchange capacity, solubility, water uptake, dimensional change, hydrolytic stability and ion conductivity. The self-crosslinking membranes showed improvement in durability towards common organic solvents, dimensional stability and ion conductivity.

Abstract: Anion exchange membranes based on poly(aryl ether oxadiazole)s (FPAEO) were prepared by quaternization of bromomethylated FPAEO with N-methyl imidazole. The structures of the obtained polymers were characterized and confirmed with 1H-NMR measurement. The physical and electrochemical properties of anion exchange membranes were also studied. The conductivity of FPAEO-xMIM membranes were almost higher than 10−2 S/cm at room temperature. In addition, TGA revealed that the AEMs based on imidazolium salts have excellent thermal stability. The experimental results suggested that the obtained AEMs may be potential membranes for anion exchange membrane fuel cells

Abstract: A series of fluorinated poly(aryl ether oxadiazole)s (FPEO) were synthesized and brominated with N-bromosuccinmide (NBS) which were then functionalized with quaternary guanidinium to get fluorinated anion exchange membranes （AEM）with pendant quaternary guanidinium Groups. The structure of resulting polymers was characterized by FTIR spectroscopy. The properties of the obtained membranes were investigated in terms of ion exchange capacity (IEC), swelling ratio, area resistance and vanadium permeability. The results showed that the novel anion exchange membranes possess much higher selectivity in VRB system. The permeation rate of vanadium ions of GFPEO is 0.21×10-7 cm2min-1 which is much lower compared with that of Nafion.

Abstract: Poly(vinylidene fluoride)(PVDF)-SiO₂ anion-exchange membranes was prepared by blending method with the avoidance of chloromethylation. Various membranes were prepared with different content of SiO₂ nanoparticles. These membranes were extensively characterized for their surface morphology, thermal stability, tensile properties, water content and permselectivity property using SEM, TGA, water uptake and ion exchange capacity measurements. It was found that physicochemical properties of the PVDF/SiO₂ membranes were found to be highly dependent on the SiO₂ nanoparticles content in the membrane matrix.

Abstract: Novel anion exchange membranes were synthesized by grafted copolymerization of 1-vinylimidazole onto pre-irradiated ethylene-tetrafluoroethylene copolymer (ETFE) film, followed by quaternization and alkalization. The structure of the membranes was studied by Fourier transform infrared (FT-IR). The physicochemical and electrochemical properties of the membranes were also characterized. The ionic conductivity of the synthesized membrane is 0.03 S/cm at 30°C. This result indicates that the membrane is suitable polymer electrolyte membrane and so may find potential applications in alkaline membrane fuel cells.

Abstract: A series of hydroxyl conducting anion exchange membranes based on the copolymer of vinylbenzyl chloride, butyl methacrylate and fluoro-polyacrylate were prepared by radical polymerization, quaternization and alkalization. The reaction conditions of polymerization were discussed and the potential applications of the resulting membranes in alkaline fuel cells were assessed. The results show that the membranes have adequate conductivity for fuel cell application.