The effect of tin on the degradation of LaNi5−Sn  metal hydrides during thermal cycling

Bowman, Robert C.; Luo, Ching‐Zong; Ahn, Channing C.; Witham, C.; Fultz, B.

doi:10.1016/0925-8388(94)01337-3

Cited by 164 publications

(85 citation statements)

References 23 publications

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“…8 Pneumatic valve operation and pressure and temperature data monitoring were computer controlled, permitting automatic isotherm data collection. The system was thoroughly leak checked at 200 bar and calibrated to ensure reliable determination of the hydrogen storage properties.…”

Section: ͓S0003-6951͑98͒04549-5͔mentioning

confidence: 99%

Hydrogen desorption and adsorption measurements on graphite nanofibers

Ahn

Ratnakumar

et al. 1998

Applied Physics Letters

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225

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Graphite nanofibers were synthesized and their hydrogen desorption and adsorption properties are reported for 77 and 300 K. Catalysts were made by several different methods including chemical routes, mechanical alloying, and gas condensation. The nanofibers were grown by passing ethylene and H 2 gases over the catalysts at 600°C. Hydrogen desorption and adsorption were measured using a volumetric analysis Sieverts' apparatus, and the graphite nanofibers were characterized by transmission electron microscopy and Brunauer-Emmett-Teller surface area analysis. The absolute level of hydrogen desorption measured from these materials was typically less than the 0.01 H/C atom, comparable to other forms of carbon. © 1998 American Institute of Physics. ͓S0003-6951͑98͒04549-5͔The main impediment to the use of hydrogen as a transportation fuel is the lack of a suitable means of storage. Compressed gas storage is bulky and requires the use of high strength containers. Liquid storage of hydrogen requires temperatures of 20 K and efficient insulation. Solid state storage offers the advantage of safer and more efficient handling of hydrogen, but promises at most 7% hydrogen by weight and more typically 2%. There has therefore been much interest in recent reports 1 that certain carbon graphite nanofibers 2 can absorb and retain 67 wt % hydrogen gas at ambient temperature and moderate pressures ͑i.e., up to 23 standard liters or 2 g of hydrogen per gram of carbon at 50-120 bar͒. The lowest hydrogen adsorption reported for any graphite fiber microstructure was 11 wt %. 1 Approximately 90% of the absorbed hydrogen was claimed to be desorbed at ambient temperature by reducing the pressure, while the balance is desorbed upon heating. Such claims are especially noteworthy, given that, up to this point, the typical best value of hydrogen adsorption in carbon materials has been on the order of 4 wt %, or 0.5 H/C ͑although there is also a recent claim that up to 10 wt % was achieved for H storage in single wall nanotubes 3 ͒. Owing to the potential importance of new materials with high hydrogen storage capacity for the worldwide energy economy, transportation systems and interplanetary propulsion systems, we have synthesized graphitic structures of appropriate morphology to make our own measurements of hydrogen absorption and desorption.Several graphite nanostructured materials were prepared using Fe-Cu catalysts of different compositions, in order to generate a range of fiber sizes and morphologies. We used either chemical methods, mechanical alloying, or gas condensation to produce the catalysts. The chemical method consisted of reduction of Fe and Cu nitrate precursors using the generic conditions of Rodriguez and Baker that produce high yields of graphite nanofibers. 2,4,5 Mechanically alloyed catalysts were produced using a SPEX 8000 mixer/mill using Fe and Cu powders in appropriate proportions. 6 A variation of the gas condensation method 7 was also used to produce catalyst.Catalysts were placed in a tube furnace and their surface ...

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Section: ͓S0003-6951͑98͒04549-5͔mentioning

confidence: 99%

Hydrogen desorption and adsorption measurements on graphite nanofibers

Ahn

Ratnakumar

et al. 1998

Applied Physics Letters

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225

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“…The corresponding energy difference is, at least in part, available to produce the plastic deformation in the material that accommodates the volume difference between the metal and hydride phases [19,31,32]. In the case of LaNi 5 the internal stresses involved in the phase transformation are very high, stabilizing an intermediate b phase [33] that has not been observed in LaNi 5Àx Sn x alloys [15,34]. Fultz et al [29] have shown that during the hydriding process, internal hydrogen distribution is more homogeneous for the ternary alloys containing Sn than in LaNi 5 .…”

Section: 3mentioning

confidence: 96%

Dynamic measurements of hydrogen reaction with LaNi5−xSnx alloys

Borzone¹,

Baruj²,

Blanco³

et al. 2013

International Journal of Hydrogen Energy

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Metal hydrides AB5Compression Purification a b s t r a c tThe study focuses on the reaction between hydrogen gas and LaNi 5Àx Sn x alloys, where 0 x 0.5, in broad temperature and pressure ranges. It was performed by means of dynamic volumetric techniques using specific equipment developed at our laboratory. IntroductionHydrides belonging to the so-called AB 5 family have been intensively studied during the last decades due to their potential for storing or purifying hydrogen. These alloys combine an extended range of equilibrium pressures with hydrogen and fast reaction kinetics at room temperature. Although their relatively low gravimetric capacity (around 1 wt.% H) in comparison with newly developed hydrogen storage materials hinders their use for mobile applications, they are still convenient for static applications. Among the AB 5 alloys, LaNi 5 has been the object of numerous studies due to its good hydrogen interaction properties at room temperature [1e3], its adequate resistance to cycling degradation[4e6] and to the possibility of recovering the material after degradation by means of a simple thermal treatment [4,7]. Several of LaNi 5 hydrogen interaction properties can be modified or adapted to a specific need by the partial substitution of its elements [8e10]. For example, it is possible to increase the equilibrium pressure by substituting part of La by Ce [11], or to achieve an improvement in electrochemical properties by replacing a fraction of La by Dy [12]. The partial substitution of Ni, on the other hand, has been reported to improve the resistance to thermal and pressure cycling degradation [3]. Ni substitutions also produce changes in the equilibrium pressure which could be useful for the development of applications based on these materials. In particular, it has been found that the substitution of small amounts of Ni by * Corresponding author. Centro Ató mico Bariloche, Av. Bustillo 9500, 8400 Bariloche, Argentina. Tel.: þ54 294 4445278; fax: þ54 294 4445299.E-mail address: baruj@cab.cnea.gov.ar (A. Baruj).Available online at www.sciencedirect.com journal h om epa ge: www.elsev ier.com/locate/he i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 8 ( 2 0 1 3 ) 7 3 3 5 e7 3 4 3

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“…For example, LaNi 5 can experience a reduction in capacity of 56% after 520 cycles at 500 K [24]. Improvements can be made by substituting Al or Sn [24,25]. For example, LaNi 4.8 Sn 0.2 only experiences capacity loss of 10% after 1330 cycles at 500 K. This illustrates that degradation through disproportionation and also contamination is an issue that affects candidate hydrides for compressors to different levels.…”

Section: Compression Performance Of the Studied Casesmentioning

confidence: 98%

“…This can result in reduction of the capacity and increased plateau slopes. For example, LaNi 5 can experience a reduction in capacity of 56% after 520 cycles at 500 K [24]. Improvements can be made by substituting Al or Sn [24,25].…”

Section: Compression Performance Of the Studied Casesmentioning

confidence: 99%

Numerical study on a two-stage Metal Hydride Hydrogen Compression system

Gkanas

Grant

Stuart

et al. 2015

Journal of Alloys and Compounds

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A multistage metal hydride hydrogen compression (MHHC) system uses a combination of hydride materials in order to increase the total compression ratio, whilst maximizing the hydrogenation rate from the supply pressure at each stage. By solving the coupled heat, mass and momentum conservation equations simultaneously the performance of a MHHC system can be predicted. In the current work a numerical model is proposed to describe the operation of a complete compression cycle. Four different MHHC systems are examined in terms of maximum compression ratio, cycle time and energy consumption and it was found that the maximum compression ratio achieved was 22:1 when operating LaNi 5 (AB 5 -type) and a Zr-V-Mn-Nb (AB 2 -type intermetallic) as the first and second stage alloys respectively in the temperature range of 20 °C (hydrogenation) to 130 °C (dehydrogenation).

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The effect of tin on the degradation of LaNi5−Sn metal hydrides during thermal cycling

Cited by 164 publications

References 23 publications

Hydrogen desorption and adsorption measurements on graphite nanofibers

Hydrogen desorption and adsorption measurements on graphite nanofibers

Dynamic measurements of hydrogen reaction with LaNi5−xSnx alloys

Numerical study on a two-stage Metal Hydride Hydrogen Compression system

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