Showing papers on "Hydrogen storage published in 1995"
TL;DR: In this paper, the performance of a metal hydride electrode is determined by both the kinetics of the processes occurring at the metal/electrolyte interface and the rate of hydrogen diffusion within the bulk of the metal.
Abstract: Metal hydrides are being used as electrodes in nickel/metal-hydride batteries because of their ability to store large quantities of hydrogen and because of their many advantages over conventional lead-acid and nickel-cadmium batteries. The performance of a metal hydride electrode is determined by both the kinetics of the processes occurring at the metal/electrolyte interface and the rate of hydrogen diffusion within the bulk of the metal. The constant potential and constant current discharge techniques were used to determine the hydrogen diffusion coefficients in an LaNi{sub 4.25}Al{sub 0.75} electrode. The values obtained were 2.97 {times} 10{sup {minus}11} and 3.30 {times} 10{sup {minus}11} cm{sup 2}/s, respectively. The advantages and disadvantages of these two techniques are discussed.
478 citations
TL;DR: In this paper, the use of zeolites as media for hydrogen storage was investigated using different pore architecture and composition at temperatures from 293 to 573K and pressures from 2.5 to 10.0 MPa.
321 citations
TL;DR: In this article, the hydrogen storage characteristics of nanocrystalline Mg2Ni with grain sizes of about 20-30 nm were investigated and improvements were found in the kinetics of hydrogen absorption and in the activation pretreatment.
295 citations
TL;DR: In this article, the authors showed that substitution of only a small amount of tin suppressed the rate of hydrogen absorption-desorption reactions during thermal cycling from room temperature to over 500 K.
135 citations
TL;DR: In this article, the hydrogen storage materials were made by mechanical milling of mixed elemental magnesium and FeTi1.2 alloy powders, and the hydrogen absorption and desorption characteristics of powders milled for various times were evaluated.
109 citations
TL;DR: In this article, the effects of mechanical alloying and hydriding-dehydriding cycling on the reaction of Mg in the mixtures are investigated. And the effect of these two types of cycles on the hyddriding and dehydriding properties of these materials is investigated.
99 citations
TL;DR: In this article, the hydriding and dehydriding kinetics of Mg are reviewed, and it is reported that the hyddriding reaction is nucleation-controlled under certain conditions and progress by a mechanism of nucleation and growth.
Abstract: The hydriding and dehydriding kinetics of Mg are reviewed. It is reported that the hydriding and dehydriding reactions of Mg are nucleation-controlled under certain conditions and progress by a mechanism of nucleation and growth, and that the hydriding rates of Mg are controlled by the diffusion of hydrogen through a growing Mg hydride layer.
98 citations
TL;DR: In this article, a stoichiometric gas mixture for methanol synthesis (3H2 + CO2) was found to require an energy input of less than 1.4 MJ mol−1, corresponding to a higher heating value efficiency of over 60%.
97 citations
TL;DR: In this paper, experimental results of a combined absorption and electrodialysis process for the CO2 recovery from the atmosphere are presented as the first step in an environmentally neutral fuel production.
80 citations
TL;DR: In this paper, it was found that 0.8 g lithium nitrate added to a solution of 1 g chitosan dissolved in 100 ml 1% acetic acid produces a film, via the solution cast technique, with a maximum electrical conductivity of the order of 10−4 S cm−1.
79 citations
TL;DR: In this paper, the effect of stoichiometric ratio on the electrochemical properties of negative electrodes was investigated for alloys with composition Mm(Ni3.6Mn0.4Al0.3Co0.7)x (Mm = misch metal, 0.88 ⊽ x ⩽ 1.12), and discharge capacity at a current density of 0.2 A g−1 increased with an increase in unit cell volume of the alloys in the range of x = 0.96−1.12.
TL;DR: In this article, various Mg2Ni-type hydrogen-storage alloy electrodes are prepared and characterized at room temperature, and the discharge capacity is improved markedly via partial substitution of titanium for magnesium and iron for nickel in the Mg 2Ni alloy.
TL;DR: In this article, the hydriding and dehydriding kinetics of mixtures of magnesium and a LaNi5 type MM′5 alloy were investigated at various temperatures and pressures.
TL;DR: The Mg-composites as a hydrogen storage material are those in which such a finely divided magnesium is in intimate contact with graphite containing synergism between Mg and aromatic carbons in graphite as discussed by the authors.
Patent•
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TL;DR: In this article, a fuel cell consisting of an aqueous alkaline solution of electrolyte containing a hydrogen-releasing agent selected from the group consisting of NaBH4, KBH4 and LiAlH4 was presented.
Abstract: The present invention relates to a fuel cell comprising an aqueous alkaline solution of electrolyte containing a hydrogen-releasing agent selected from the group consisting of NaBH4, KBH4, LiAlH4, KH and NaH, an oxygen electrode as a cathode and a hydrogen storage alloy electrode as an anode
TL;DR: In this article, the diffusion kinetics of the hydrogen atom in the alloys were discussed based on the thermodynamic stability of the resulting hydrides and electrostatic interaction between foreign metals and hydrogen.
TL;DR: In this paper, a series of TiMn multicomponent alloys based on the composition TiMn 2 with high hydrogen storage capacity were investigated, and it was found that the alloy Ti 0.8 Zr 0.3 Mn 1.4 Mo 0.1 V 0.2 Cr 0.
Abstract: A series of TiMn multicomponent alloys based on the composition TiMn 2 with high hydrogen storage capacity were investigated. It is found that the alloy Ti 0.8 Zr 0.3 Mn 1.4 Mo 0.1 V 0.2 Cr 0.2 has a maximum hydrogen capacity of 3.4 H/M (mol H/mol alloy), theoretical electrochemical capacity of 560 mAh g −1 , exhibits a plateau pressure range between 0.006 and 0.01 MPa at 293 K. Addition of the elements Si and Al in a four component alloy causes the hydrogen storage capacity to decrease and plateau pressure to increase. Addition of a small amount of Mo increases hydrogen storage capacity. The substitution of V for Mn lowers the plateau pressure dramatically. The phase composition and microstructure of Ti 0.8 Zr 0.3 Mn 1.4 Mo 0.1 V 0.2 Cr 0.2 , which is one of the highest capacity TiMn 2 -based alloys, has been studied by X-ray diffraction, optical microscopy and scanning electron microscopy.
TL;DR: In this paper, the mechanism underlying the rapid, early, capacity loss of titanium-based (Ti2Ni) hydrogen-storage alloys was examined via X-ray diffraction analysis.
TL;DR: Amorphous La-Ni thin films over a wide range of composition were fabricated by electron beam evaporation in ultra-high vacuum as discussed by the authors, and the structure and composition of these films were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA).
TL;DR: The rare earth intermetallics for metal-hydrogen batteries are discussed in this paper, where a hydrogen storage alloy (metal hydride) is used as a negative electrode material.
Abstract: Publisher Summary The rare earth intermetallics for metal-hydrogen batteries are discussed in this chapter. The chapter describes the research and development (R&D) for nickel–metal hydride batteries in which a hydrogen storage alloy (metal hydride) is used as a negative electrode material. This type of battery has been attracting a great deal of attention as a new non-military battery because it is characterized by several advantages over the conventional secondary batteries, such as high energy density, compatibility with a nickel–cadmium battery, and no consumption of the electrolyte solution during charge–discharge cycling. Because the charge–discharge characteristics of the negative electrode can be widely altered depending on the kind and composition of alloys used, extensive R&D work has been conducted from this point of view. Effects of various alloying elements on the behavior of metal hydride electrodes are summarized in the chapter. The development of a new hydrogen storage alloy of high performance and low cost is a key to further development of metal hydride batteries.
TL;DR: In this article, the properties of polycrystalline alloys with hexagonal C14-and/or cubic C15-type structures were determined by X-ray and neutron diffraction.
TL;DR: In this article, the applicability of six hydrogen absorbing pseudobinary AB5 and AB2 alloys for near ambient temperature (10 − 50 °C) and atmospheric pressure (1 −10 … 20 bar) applications was investigated.
TL;DR: In this paper, a model for the hydriding/dehydriding processes of multi-component magnesium-base alloys is proposed, based on surface segregation and interface microcrack passages.
Patent•
06 Nov 1995TL;DR: An improved metal hydride hydrogen storage alloy electrochemical cell (10) includes a positive electrode (20) and a negative electrode (30) having disposed therebetween, a polymer electrolyte (40) comprising a polymer support structure fabricated of, for example, polyvinyl alcohol or polyvinylon acetate, and having dispersed therein an electrolyte active species such as, for instance, KOH as mentioned in this paper.
Abstract: An improved metal hydride hydrogen storage alloy electrochemical cell (10) includes a positive electrode (20) and a negative electrode (30) having disposed therebetween, a polymer electrolyte (40). The polymer electrolyte (40) comprises a polymer support structure fabricated of, for example, polyvinyl alcohol or polyvinyl acetate, and having dispersed therein an electrolyte active species such as, for example, KOH. The improved electrolyte for a metal hydride hydrogen storage alloy cell provides a battery cell free from electrolyte leakage, and having ionic conductivities which allow for an efficient use of the metal hydride electrodes.
TL;DR: In situ x-ray absorption spectroscopy (XAS) studies were done on three metal hydride electrodes, LaNi, LaNns, and LaNi~, in 6M KOH as mentioned in this paper, and the results indicate that XAS is a very useful technique for the study of alloy hydrides.
Abstract: In situ x-ray absorption spectroscopy (XAS) studies were done on three metal hydride electrodes, LaNi~, LaNi~.sSns.2, La0.sCe02Ni48Sn0.2, in 6M KOH. Ex situ measurements were also made on dry uncycled electrodes and on material from an La0.sCe0.2Ni48Sn0.2 electrode that had been cycled 25 times. Comparison of the in situ XAS at the Ni K and at the La L3 edge of charged and discharged electrodes indicates large changes in the electronic and structural characteristics on introduction of hydrogen. Results at the Ce L2 edge in La~.sCe~.2Ni4.~Sn0.~ show a transition from a mixed valent c~ to a -/-like Ce state as the lattice expands during charge. Ex situ x-ray absorption near-edge structures (XANES) at the Ni K edge indicate that the additions of either Ce or Sn fill empty Ni 3d states. The Ni K edge extended x-ray absorption fine structures (EXAFS) for all three alloys in the dry uncharged state were similar, indicating that minor substitutions for either the A or B component do not substantially change the structure. The Sn substitution causes an increase both in a and c axis as evidenced from increase in the Ni-Ni and the Ni-La distances. Partial substitution of La by Ce causes a slight contraction in the Ni-La distance. The Ni XANES and EXAFS indicate that about 6 % of the Ni in the La0.sCe0.2Ni~.sSn02 corroded after 25 cycles. Ce XANES on the cycled electrode indicates some corrosion of Ce and the formation of Ce (III) state. The results indicate that XAS is a very useful technique for the study of alloy hydrides, particularly the role of electronic structure, the environment around minor constituents, and the corrosion of individual components. Recent advances in the development of stable metal hydride alloy electrodes have led to their use as a replacement for cadmium anodes in rechargeable alkaline batteries. I Present battery electrodes are either AB2 or AB5 type alloys. The performance and life of these alloys greatly depend on their composition. In the case the AB5 type alloys, substitution of either component in the prototype alloy, LaNi~, with small amounts of other alloying elements can have major effects in the performance and stability of the alloy. Previous results with Ce, Sn, and Co substitution have demonstrated promising results in battery electrodes. 2 Recent results 3 have shown that Sn and Co substitution for some of the Ni causes a lowering of the hydrogen plateau pressure. Partial substitution of La with Ce results in improved corrosion resistance and cycle life. The Ce substitution also causes an increase in the hydrogen plateau pressure. An understanding of the mechanism of these effects would help in optimizing metal hydrides for various hydrogen storage and battery applications.
Patent•
01 Dec 1995
TL;DR: In this article, rare earths from the hydrogen storage alloys in the negative electrodes are precipitated, then the disintegration solution is solvent-extracted in such conditions (pH value, choice of solvent, volume ratio between the phases) that the quantity and atomic ratio of nickel and cobalt is the same in the aqueous phase as in the scrap.
Abstract: When recycling used nickel-metal hydride accumulators, scrap batteries are dissolved in sulphuric acid after the coarse components have been mechanically separated in a magnetic wind sifter. Rare earths (from the hydrogen storage alloys in the negative electrodes), iron and aluminium are precipitated, then the disintegration solution is solvent-extracted in such conditions (pH value, choice of solvent, volume ratio between the phases) that the quantity and atomic ratio of nickel and cobalt is the same in the aqueous phase as in the scrap. They can thus be recovered together by simultaneous electrolysis. The separated product forms a pre-alloy that may be used together with the precipitated rare earths converted by an electrometallurgical process into mischmetal to produce new hydrogen storage alloys.
Patent•
21 Feb 1995
TL;DR: In this paper, the authors proposed to favorably regulate hydrogen by additionally providing a heat exchanging device different from a cooling device so as to effectively utilize reaction heat of hydrogen storage alloy for the cooling device, and interposing a hydrogen compressor on a hydrogen flow passage connecting together a MH-built-in tank and a hydrogen consuming part.
Abstract: PURPOSE:To favorably regulate hydrogen by additionally providing a heat exchanging device different from a cooling device so as to effectively utilize reaction heat of hydrogen storage alloy for the cooling device, and interposing a hydrogen compressor on a hydrogen flow passage connecting together a MH- built-in tank and a hydrogen consuming part. CONSTITUTION:In a hydrogen fuel automobile 1, hydrogen 81 is supplied from a MH-built-in tank 10 receiving hydrogen storage allay to a hydrogen consuming part 11 generating power driving a vehicle. A cooling device 20 is provided with a condenser 21 condensing compressed refrigerant 82 and an evaporator 22 evaporating expanded refrigerant 82. Fourther, a heat exchanging device 30 is formed with a part of a thermal medium flow passage 33 in the MH-built- in tank 10. In such constitution, a first heat exchanger 31 arranged in the MH- built-in tank 10 and a second heat exchanger 32 arranged on a passage 41 of air 85 cooled by the cooling device 20 are arranged in the heat exchanging device 30. A hydrogen compressor 13 is interposed on a hydrogen flow passage 12 connecting together the MH-built-in tank 10 and the hydrogen consuming part 11.
01 Jan 1995
TL;DR: In this article, the authors provide an introduction to and overview of the important scientific and practical aspects of hydrogen interactions with metals, focusing on the controlled absorption and desorption of hydrogen into and out of metals, especially the area of rechargeable metal hydrides.
Abstract: This chapter provides an introduction to and overview of the important scientific and practical aspects of hydrogen interactions with metals. In particular, it concentrates on the controlled absorption and desorption of hydrogen into and out of metals, especially the area of rechargeable metal hydrides. The subject of the hydrogen degradation of structural materials is also briefly discussed.
01 Jan 1995
TL;DR: In this paper, a technical description of both types of underground storage and illustrates the economic case for future hydrogen utilizations with two examples: annual storage in aquifers and daily storage in salt cavities.
Abstract: Hydrogen is stored in bulk quantities in liquid form in 360 and 3800 cubic meter tanks and in gas form underground. The two techniques of underground storage for hydrogen in the future are analogous to those used for natural gas. Cavities created by dissolving salt layers, affording volume capacities of the order of 100,000 m3, make it possible to store a few million cubic meters of H2. Storage facilities in aquifers fitted out in the same way as natural gas fields provide capacities of the order of 100 to 1000 million m3. This paper gives a technical description of both types of underground storage and illustrates the economic case for future hydrogen utilizations with two examples: annual storage in aquifers and daily storage in salt cavities.