A Platinum‐Free Zero‐Carbon‐Emission Easy Fuelling Direct Hydrazine Fuel Cell for Vehicles

Asazawa, Koichiro; Yamada, Kôji; Tanaka, Hiroyuki; Oka, Akinori; Taniguchi, Masatoshi; Kobayashi, Tetsuhiko

doi:10.1002/anie.200701334

Cited by 327 publications

(239 citation statements)

References 12 publications

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“…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 cells were initially conceived with liquid basic electrolytes containing alkali metal cations, such as sodium hydroxide or potassium hydroxide. Recently, polymers with tethered organic cations have been demonstrated as solid polymer anion-exchange membranes (AEMs) for alkaline fuel cells.…”

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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“…On the other hand, transferring the non-Pt catalysts from AFC to APEFC is not as straightforward as expected. Although Ag has been found to be still applicable as the cathode catalyst for oxygen reduction in APEFC (18,19), attempts to use Ni as the anode catalyst for hydrogen oxidation failed unexpectedly and unexceptionally until now (9). proaches in both the APE and the anode catalyst.…”

mentioning

confidence: 99%

“…The electrolysis method used in AFC to activate the Ni anode in a separate electrolyzer (28,29) is, unfortunately, inapplicable for APEFC using an electrode-membrane-assembly (MEA) structure, unless a bifunctional oxygen electrode can be found. For this reason, Tanaka and coworkers (9) at Daihatsu Motors had to use hydrazine, instead of gaseous hydrogen, as the fuel for APEFC. In the present work, we succeeded in addressing this problem by tuning the surface electronic property of Ni through a combined computational and experimental study.…”

mentioning

confidence: 99%

Alkaline polymer electrolyte fuel cells completely free from noble metal catalysts

Pan

Huang

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

733

500

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In recent decades, fuel cell technology has been undergoing revolutionary developments, with fundamental progress being the replacement of electrolyte solutions with polymer electrolytes, making the device more compact in size and higher in power density. Nowadays, acidic polymer electrolytes, typically Nafion, are widely used. Despite great success, fuel cells based on acidic polyelectrolyte still depend heavily on noble metal catalysts, predominantly platinum (Pt), thus increasing the cost and hampering the widespread application of fuel cells. Here, we report a type of polymer electrolyte fuel cells (PEFC) employing a hydroxide ionconductive polymer, quaternary ammonium polysulphone, as alkaline electrolyte and nonprecious metals, chromium-decorated nickel and silver, as the catalyst for the negative and positive electrodes, respectively. In addition to the development of a high-performance alkaline polymer electrolyte particularly suitable for fuel cells, key progress has been achieved in catalyst tailoring: The surface electronic structure of nickel has been tuned to suppress selectively the surface oxidative passivation with retained activity toward hydrogen oxidation. This report of a H2-O2 PEFC completely free from noble metal catalysts in both the positive and negative electrodes represents an important advancement in the research and development of fuel cells.nonprecious metals ͉ hydrogen oxidation ͉ oxygen reduction F uel cells have been recognized as an alternative powergeneration technique for the future in both mobile and stationary uses (1, 2). After decades of evolution, fuel cells of various types have been developed (2), such as alkaline fuel cell (AFC), phosphoric acid fuel cell (PAFC), molten carbonate fuel cell (MCFC), solid oxide fuel cell (SOFC), and polymer electrolyte fuel cell (PEFC). Among them, PEFC has been the most developed one in the past 2 decades (3), featuring rapid startup and high power density particularly suitable for vehicle applications (1-3).Compared with the aqueous electrolytes traditionally used in low-temperature fuel cells, polymer electrolytes completely eliminate the problems caused by electrolyte leakage and can effectively separate the fuels (such as hydrogen) and the oxidant (oxygen) with a thin film of a few tens of microns in thickness. For decades, the commonly used polymer electrolytes have been limited to proton exchange membranes, typically Nafion . Nowadays, many Nafion-based fuel cell systems of different sizes are being demonstrated or tested on a variety of applications across the world. Although they are promising, the Nafion-based fuel cells still face a number of obstacles to commercialization, one of which has been the severe dependence of catalysts on platinum (Pt), an expensive and scarce resource in the earth. Such dependence stems from the strong acidic nature of the protonexchange membrane; and thermodynamically, only noble metals can be relatively stable in this corrosive environment. Despite tremendous efforts devoted to the search for non-...

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“…Most research and development on PEFCs and direct FCs has concentrated on the CEM-type. However, interest in AEM-type direct FCs has recently been growing with various fuels, such as methanol 7)～10) , ethanol 10) , ethylene glycol 9)～11) , and hydrazine 12) . In these studies, a hydrocarbon polymer carrying quaternary ammonium groups chemically bonded as side chains has often been used as an AEM.…”

Section: Biomass Fuelsmentioning

confidence: 99%

“…The so-called "flooding" phenomenon, in which oxygen diffusion is inhibited by water generated at the cathode, is often observed in the CEM-type, but can be avoided in the AEM-type, where water is generated at the anode. Pt-free fuel cells have been successfully demonstrated by replacing the conventional acidic membrane with an AEM 12) . However, the primary problem with AEM-type fuel cells is that acidic impurities, e.g.…”

Section: Ethanolmentioning

confidence: 99%