Anion exchange membranes for alkaline fuel cells: A review

Merle, G Géraldine; Weßling, Matthias; Nijmeijer, DC Kitty

doi:10.1016/j.memsci.2011.04.043

Cited by 1,564 publications

(1,294 citation statements)

References 221 publications

(332 reference statements)

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“…7,8 Alkaline fuel cells (AFCs) have received significant interest in recent years relative to acidic fuel cells, 9−14 because of advantages when operating under alkaline conditions, which include enhancement of the electrode reaction kinetics, especially at the cathode, and the catalysts are not subjected to corrosion at high pH. 9,12,13 Consequently, non-noble metals or inexpensive metal oxides can be used as catalysts to greatly reduce the cost of the device. 13−16 In addition, high energy density liquids and gases such as ethanol, hydrazine, and ammonia can be adopted as fuels.…”

Section: ■ Introductionmentioning

confidence: 99%

Highly Stable, Anion Conductive, Comb-Shaped Copolymers for Alkaline Fuel Cells

et al. 2013

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To produce an anion-conductive and durable polymer electrolyte for alkaline fuel cell applications, a series of quaternized poly(2,6-dimethyl phenylene oxide)s containing long alkyl side chains pendant to the nitrogen-centered cation were synthesized using a Menshutkin reaction to form combshaped structures. The pendant alkyl chains were responsible for the development of highly conductive ionic domains, as confirmed by small-angle X-ray scattering (SAXS). The combshaped polymers having one alkyl side chain showed higher hydroxide conductivities than those with benzyltrimethyl ammonium moieties or structures with more than one alkyl side chain per cationic site. The highest conductivity was observed for comb-shaped polymers with benzyldimethylhexadecyl ammonium cations. The chemical stabilities of the comb-shaped membranes were evaluated under severe, accelerated-aging conditions, and degradation was observed by measuring IEC and ion conductivity changes during aging. The comb-shaped membranes retained their high ion conductivity in 1 M NaOH at 80°C for 2000 h. These cationic polymers were employed as ionomers in catalyst layers for alkaline fuel cells. The results indicated that the C-16 alkyl side chain ionomer had a slightly better initial performance, despite its low IEC value, but very poor durability in the fuel cell. In contrast, 90% of the initial performance was retained for the alkaline fuel cell with electrodes containing the C-6 side chain after 60 h of fuel cell operation. ■ INTRODUCTIONFuel cells are efficient energy conversion devices that generate electric power from energy-dense chemical fuels and have been attracting attention as a clean energy technology. 1−3 The most widespread low-temperature fuel cell technologies are based on sulfonated polymer membranes to separate the oxidant and fuel chambers and conduct protons between the anode and cathode of the cell. 4−6 These proton exchange membrane fuel cells (PEMFC) principally employ Nafion, a product from DuPont, as the sulfonated polymeric proton conductor. PEMFCs require platinum or other precious metal-based catalysts because these are the only types of metal catalysts stable under the low pH and electrochemical conditions of an operating cell. The expensive Pt-based catalysts, combined with perfluorinated membranes and corrosion-resistant cell hardware increase the cost of PEMFC devices beyond what is currently commercially viable. 7,8 Alkaline fuel cells (AFCs) have received significant interest in recent years relative to acidic fuel cells, 9−14 because of advantages when operating under alkaline conditions, which include enhancement of the electrode reaction kinetics, especially at the cathode, and the catalysts are not subjected to corrosion at high pH. 9,12,13 Consequently, non-noble metals or inexpensive metal oxides can be used as catalysts to greatly reduce the cost of the device. 13−16 In addition, high energy density liquids and gases such as ethanol, hydrazine, and ammonia can be adopted as fuels. 17,18 Alkaline fuel ...

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Section: ■ Introductionmentioning

confidence: 99%

Highly Stable, Anion Conductive, Comb-Shaped Copolymers for Alkaline Fuel Cells

et al. 2013

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“…The crosslinked copolymer/silica composite membranes, QP(DNB/NB-SiO 2 -x), were obtained by further reacting P(DNB/NB-OH) with TSPCA and GA via sol-gel method (Scheme 1). 1 H NMR spectrum of QP(DNB/NB-OH) copolymer was shown in Fig. 3.…”

Section: H Nmr Spectrum Analysismentioning

confidence: 99%

Crosslinked hydroxyl‐conductive copolymer/silica composite membranes based on addition‐type polynorbornene for alkaline anion exchange membrane fuel cell applications

Jiang

Wang

et al. 2017

Polymer Engineering & Sci

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Crosslinked hydroxyl-conductive copolymer/silica composite membranes based on addition-type polynorbornene, poly(dodoxymethylene norbornene-co-norbornene-3-(trimethylpropyl ammonium)-functionalized silica (QP(DNB/ NB-SiO 2 ), were prepared by a sol-gel method. Copolymer composite membranes with different degree of quaternary ammonium functional silica, designated as QP(DNB/NBSiO 2 -X) (X 5 5, 10, 15 and 25 wt%, respectively), displayed good dimensional stabilities with low in-plane swelling rate of 1.32-3.7%, good mechanical properties with high elastic modulus of 605.4-756.8 MPa and high tensile strength of 13.2-20 Mpa. The achieved copolymer composite membranes could self-assemble into a microphase-separated morphology with randomly oriented long-range aliphatic chain/cylinder ionic channels that were imbedded in the hydrophobic PNB matrix. Among these membranes, the QP(DNB/NB-SiO 2 -25) showed the parameter with ionic conductivity of 9.33 3 10 23 S cm 21 , methanol permeability of 2.89 3 10 27 cm 2 s 21 , and ion-exchange capacity(IEC) of 1.19 3 10 23 mol g 21 . A current density of 82.3mA cm 22 , the open circuit voltage of 0.65 V and a peek power density of 32 mW cm 22 were obtained. POLYM. ENG. SCI., 58:13-21, 2018.

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“…because it is the most conducting of all alkaline hydroxides. [1]. The major drawback of AFC is that KOH electrolyte is very sensitive to CO 2 that forms carbonates crystals such as K 2 CO 3 which then precipitate in the cell.…”

Section: Direct Methanol Fuel Cellmentioning

confidence: 99%

“…The major drawback of AFC is that KOH electrolyte is very sensitive to CO 2 that forms carbonates crystals such as K 2 CO 3 which then precipitate in the cell. Another disadvantage is related to the amount of liquid electrolyte that may cause electrode flooding or drying [1]. Later on, advances in PEMFC brought the idea of…”

Section: Direct Methanol Fuel Cellmentioning

confidence: 99%

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Nitrogen-doped graphene with enhanced oxygen reduction activity produced by pyrolysis of graphene functionalized with imidazole derivatives

Borghei

Azcune

Carrasco

et al. 2014

International Journal of Hydrogen Energy

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Direct methanol fuel cells (DMFC) are great candidates for portable power source applications. However, the sluggish reaction kinetics are key challenges in DMFC technology. The state-of-the-art electrocatalysts are Pt-based catalysts supported on carbon black. However, the high price of Pt, corrosion of carbon support and Pt degradation are the main problems.In this thesis, carbon nanomaterials, namely few-walled carbon nanotubes (FWCNTs) and graphitized nanofibers (GNFs) were used as catalyst supports in the search for stable and durable catalysts. PtRu nanocatalysts with similar particle size and composition were synthesized and deposited on FWCNTs and GNFs. The electrochemical activities for methanol oxidation were compared with that of PtRu-carbon black in acidic conditions. The half-cell electrochemical measurements revealed higher activity with PtRu-GNFs and PtRu-FWCNTs. Later, the electrocatalysts were tested in macro-and micro-DMFC. The results revealed the significant influence of the catalyst support, inomer contect, electrode structure, preparation method, as well as the fuel cell architecture on the performance of a specific electrode material. The results also highlighted the necessity of electrode composition optimization when applying new materials at the electrodes, in order to achieve the best activity and durability for a certain electrocatalyst.A special effort was also done to achieve Pt-free electrocatalysts with high activity for the oxygen reduction reaction (ORR) by introducing nitrogen heteroatoms in carbon nanomaterials, namely FWCNTs and graphite nanoplatelets (GNPs). N-FWCNTs exhibited remarkable electrocatalytic activity for ORR in alkaline media, despite their very low nitrogen content (~0.5 at.%). N-FWCNTs performed on par or better than a commercial Pt-C at the cathode of an alkaline DMFC. The N-GNPs exhibited enhanced electrocatalytic activity for ORR compared to pristine GNPs in alkaline media. The results indicated that N-doped carbon nanomaterials could be promising alternatives to their Pt counterparts to reduce fuel cell costs. However, further investigations are necessary to ascertain the real active sites in order to design more efficient and durable ORR electrocatalysts.Keywords Carbon nanomaterials, PtRu catalysts, nitrogen-doping, direct methanol fuel cell ISBN (printed) 978-952-60-6140-5 ISBN (pdf) 978-952-60-6141-2

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Anion exchange membranes for alkaline fuel cells: A review

Cited by 1,564 publications

References 221 publications

Highly Stable, Anion Conductive, Comb-Shaped Copolymers for Alkaline Fuel Cells

Highly Stable, Anion Conductive, Comb-Shaped Copolymers for Alkaline Fuel Cells

Crosslinked hydroxyl‐conductive copolymer/silica composite membranes based on addition‐type polynorbornene for alkaline anion exchange membrane fuel cell applications

Nitrogen-doped graphene with enhanced oxygen reduction activity produced by pyrolysis of graphene functionalized with imidazole derivatives

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