Showing papers on "Hydrogen storage published in 1990"

Hydrogen-alkali-metal-graphite ternary intercalation compounds

Abstract: Alkali-metal-graphite intercalation compounds (alkali-metal-GIC’s) absorb hydrogen in two ways: physisorption and chemisorption. Hydrogen uptake through the physisorption process occurs at low temperatures below about 200 K in higher stage alkali-metal-GIC’s, where hydrogen molecules are stabilized to form a two-dimensional condensed phase in the galleries of the graphite sheets. The concentration of absorbed hydrogen molecules is saturated at a rate of H2/alkali metal atom ∼2. The hydrogen physisorption shows a strong isotope effect and a swelling effect on c-axis lattice expansion. In the case of hydrogen uptake through the chemisorption process, dissociated hydrogen species are stabilized in the intercalate spaces. The activity of the chemisorption increases in the order Cs < Rb < K. The introduction of hydrogen generates a charge transfer from the host alkali metal GIC’s to the hydrogen since hydrogen has strong electron affinity. The hydrogenated potassium-GIC’s have intercalates consisting of K+-H−-K+ triple atomic layer sandwiches which are inserted between metallic graphite sheets. The inserted two-dimensional hydrogen layer is suggested to consist of H ions with a weakly metallic nature. The superconductivity of the hydrogenated potassium-GIC is also discussed in terms of the change in the electronic and lattice dynamical properties by hydrogen uptake. The hydrogen-absorption in alkali-metal-GIC’s is an interesting phenomenon in comparison with that in transition metal hydrides from the point of hydrogen storage. The hydrogen-alkali-metal-ternary GIC’s obtained from hydrogen absorption have novel electronic properties and lattice structures which provide attractive problems for GIC research. The studies of hydrogen-alkali-metal ternary GIC’s are reviewed in this article.

Catalytic hydrogen storage electrode materials for use in electrochemical cells and electrochemical cells incorporating the materials

Abstract: Disclosed is a reversible, electrochemical cell having a high electrochemical activity, hydrogen storage negative electrode. The negative electrode is formed of a reversible, multicomponent, multiphase, electrochemical hydrogen storage alloy. The hydrogen storage alloy is capable of electrochemically charging and discharging hydrogen in alkaline aqueous media. In one preferred exemplification the hydrogen storage alloy is a member of the family of hydrogen storage alloys, dericed from the V-Ti-Zr-Ni and V-Ti-Zr-Ni-Cr alloys in which the V, Ti, Zr, Ni and Cr are partially replaced by one or more modifiers, and the alloy has the composition: (V.sub.y'-y Ni.sub.y Ti.sub.x'-x Zr.sub.x Cr.sub.z).sub.a M'.sub.b M".sub.c M d iv where x' is between 1.8 and 2.2, x is between 0 and 1.5, y' is between 3.6 and 4.4, y is between 0.6 and 3.5, z is between 0.00 and 1.44, a designates that the V-Ni-Ti-Zr-Cr component, as a group is from 70 to 100 atomic percent of the alloy, b,c,d,e, . . . , are the coefficients on the modifiers, and M', M", M iii , and M iv are modifiers which may be individually or collectively up to 30 atomic percent of the total alloy. The modifiers, M', M", M iii , and M iv are chosen from Al, Mn, Mo, Cu, W, Fe, Co, and combinations thereof.

Method of preparing active magnesium-hydride or magnesium hydrogen-storer systems

Abstract: A method of preparing an active magnesium-hydride or magnesium hydrogen-storer system which can reversibly take up H2, comprising contacting finely divided magnesium hydride or metallic magnesium with a solution of a metal complex or of a metal-organic compound of a transition metal of Subgroups IV-VIII of the periodic table, and then removing the solution. The product performs better with regard to speed and efficiency upon repeated hydrogenation and dehydrogenation, as in hydrogen storage and evolution.

The influence of oxidation upon the storage capacity of LaNi5 electrodes

Abstract: The particle-size effect of LaNi5 powders on the rate of degradation of the corresponding LaNi5 electrode is reported. A linear relation between the degree of oxidation of the LaNi5 powder and the decrease in hydrogen storage capacity of the electrodes prepared from these oxidized powders was found, independent of the specific surface area of the powder.

Rectangular sealed alkaline storage battery with negative electrode comprising hydrogen storage alloy

Abstract: The present invention relates to improvement of an active material of a negative electrode in a rectangular sealed alkaline storage battery. That is, by using a hydrogen storage alloy as the active material of the negative electrode, a capacity density as a battery can be enhanced and besides, mounting a space for the battery in equipments which use the battery can be reduced and dischargeability and storability can be improved.

The effect of the electrolyte on the degradation process of LaNi5 electrodes

Abstract: The effect of the process parameters, such as temperature, charge rate and charge time, rest period, discharge rate, KOH concentration of the electrolyte and encapsulation with copper, upon the hydrogen storage capacity of LaNi5 electrodes was investigated as a function of the number of charge-discharge cycles. The decay in storage capacity of the electrodes was ascribed to a crashing-oxidation process at the surface of the LaNi5 particles. The oxidized layer at the surface of the particles was found to be formed by a reaction with the electrolyte. The growth of this layer could be diminished by encapsulation of the LaNi5 particles by copper without a reduction in the storage capacity of the electrodes.

Process and apparatus for the purification of hydrogen gas

Abstract: A process for the purification of contaminated hydrogen gas which involves, first, subjecting the hydrogen gas to a preliminary purification with a hydride-forming material which has a low hydrogen storage capacity to remove substantially all of the contaminants, followed by a primary purification of the hydrogen gas with a hydride-forming material which has a high hydrogen storage capacity, thereby extending the useful life of the hydride-forming material which has the high hydrogen storage capacity

Hydrogen storage electrode and process for producing the same

Abstract: Disclosed are a hydrogen storage electrode and a process for producing the same. The process includes the steps of: coating the surface of hydrogen storage alloy powder with copper or nickel, thereby making the hydrogen storage alloy powder into microcapsule; mixing the microcapsule with uncrosslinked silicone rubber and/or powder for forming porosity; and pressure molding the mixture of the microcapsule, the uncrosslinked silicone rubber and/or the powder for forming porosity, thereby completing the crosslinking of the uncrosslinked silicone rubber during or after the pressure molding. The hydrogen storage electrode has a reduced capacity deterioration characteristic during a high rate electric discharge and an extended charge and discharge cycle life, since the silicone rubber binds the neighboring mecorcapsules elastically, thereby preventing the microcapsules including the hydrogen storage powder from coming off, and since the powder for forming porosity forms microspaces on the boundaries between itself and the silicone rubber, thereby improving the hydrogen permeability and reducing the internal electric resistance.

Alloy preparation of hydrogen storage material

Abstract: A method for the preparation of a highly alloyed metal hydride, hydrogen storage alloy material including titanium, zirconium, vanadium, nickel and chromium. The hydrogen storage alloy material is prepared by vacuum induction melting electrochemically operative amounts of the materials in a nigh density, high purity graphite crucible, under an inert gas atmosphere.

The influence of the pretreatment of powder on the resulting properties of LaNi5 electrodes

Abstract: Both the increase in specific surface area and the decay in hydrogen storage capacity of LaNi 5 electrodes as a function of the charge-discharge cycle number are ascribed to an oxidation-crashing process. In each cycle the oxidized layer at the surface of the LaNi 5 particles in the electrodes is crashed as a result of the volume expansion of the active powder caused by hydrogen absorption followed, after desorption of the hydrogen, by an oxidation of the newly formed clean LaNi 5 surface by a reaction with the electrolyte. A similar oxidation-crashing mechanism occurs in the hydrogen gas absorption-desorption process in the presence of air or water vapour. Activation of hydrogen absorption is necessary in both processes because of a compact oxidized layer already present at the surface of the LaNi 5 particles. The slight influence of the porosity of the electrodes on their electrochemical properties may be ascribed to a high hydrogen bulk diffusion rate in the LaNi 5 as well as in the copper particles.

Surface properties and their consequences on the hydrogen sorption characteristics of certain materials

Abstract: Surface analyses (X-ray photoelectron spectroscopy, X-ray-induced Auger electron spectroscopy and Auger electron spectroscopy) results of some hydrogen storage intermetallic compounds of the type AB, AB5, A2B and the hydride, A2BH4 (A ≡ Ti, La, CaorMg; B ≡ Fe, NiorCu) show the presence of numerous oxidation (aerial) products, such as oxides, hydroxides and carbonates. In general, the hydroxide and/or carbonate species are present in small amounts and persist only on the outer passivated surface. However, there are cases where they seem to be predominant, at least in the top few layers. Therefore such species are also expected to play an important role in the surface chemistry of the alloys and hydrides similar to that observed with surface oxides. Accordingly, the activation procedure varies for the different materials. Upon activation the surface may be described as a supported metal system which in turn increases the activity thus explaining the rapid kinetics of the hydriding/dehydriding reactions upon cycling processes. The easy activation of certain alloys could also be explained on the basis of the reducibility and the thickness of the surface oxide layers. In other words, it could be demonstrated based on their oxidation resistance and the segregation behaviour of the metals. The specific reactivity of different systems are related to the segregation, oxidation, and reduction behaviours. Surface enrichment of iron in the TiFe system is demonstrated for the first time.

Hydrogen storage electrode

Abstract: PURPOSE: To enhance the oxidation resistance of a hydrogen storage alloy by providing the hydrogen storage allay with an amorphous layer, and also providing the layer on the surface of the alloy. CONSTITUTION: The progress of oxidation of a hydrogen storage alloy is caused by the enlargement of the surface area of the allay due to pulverization of crystal as the crystal is expanded and contracted by repetition of the storage and release of hydrogen. When the surface layer of the hydrogen storage alloy is provided with an amorphous layer pulverization of the alloy is restrained and the progress of oxidation of alloy powder is prevented and also the active material is prevented from falling off. When an amorphous layer is provided to an alloy of the same composition the amount of hydrogen stored in the alloy is smaller than that stored in the inner hydrogen storage alloy but the alloy has an ability to store a large amount of hydrogen so the energy density of the hydrogen storage electrode is not lowered so much as when the electrode is covered at its surface with a metal which does not contain hydrogen at all, and a new phase is generated in a boundary area between the surface layer and the internal layer and the ability of the alloy to store hydrogen would not be lost. COPYRIGHT: (C)1992,JPO&Japio

The influence of atmospheric CO2 on the surface properties of Mg2NiH4 and a comparison with some hydrogen storage alloys

Abstract: On montre l'existence de carbonate a la surface de Mg 2 NiH 4 et que le comportement a l'oxydation de l'hydrure est different de celui des alliages

Hydrogen storage body

Abstract: A hydrogen storage body comprises ultra-fine particles of a hydrogen storage material with an average particle size of 200 A or less.

Metastable hydrogen storage alloy material

Abstract: Disclosed is an improved metastable, multi-component, multi-phase hydrogen storage alloy material formed by rapid solidifcation from a melt. The improved metastable hydrogen storage alloy is characterized by a refined grain size of Approximately 1 micron or less, and the reduction, or elimination of deleterious phases. The microstructure of the alloy is relatively disordered, and each phase of the material comprises less than 50 atomic percent vanadium and chromium combined. The nominal composition is: V.sub.y'-y Ni.sub.y Ti.sub.x'-x Zr.sub.x Cr.sub.x wherein x' is between 1.8 and 2.2; x is between 0 and 1.5; y' is between 3.6 and 4.4; y is between 0.6 and 3.5; and z is between 0 and 1.44.

Organic getter materials for the removal of hydrogen and its isotopes

Abstract: Herein, we describe hydrogen getter technologies developed at SNL and KCD over the past decade. The technologies are based on the irreversible removal of hydrogen by catalytic hydrogenation of unsaturated organic compounds. Different types have been developed: crystalline getters, dialkynes combined with heterogeneous catalysts; and a polymeric getter, a thermoplastic elastomer capable of reacting with hydrogen in the presence of oxygen without producing water. These materials can remove up to 300 cc (STP) of hydrogen per gram of material, and can maintain atmospheres of less than 10 ppM hydrogen. Crystalline getters for tritium and the combination hydrogen(tritium), water, and oxygen are described. The accumulation of hydrogen is usually an undesired event. Large leaks from hydrogen storage and handling facilities pose explosion hazards. Small amounts of hydrogen that may build up in sealed containers after long storage times can damage integral components. Any tritium leak is an immediate health hazard. Hydrogen scavengers or getters can avert all of these potential problems by irreversibly removing hydrogen from such environments. In this paper, we describe the development of two types of organic getters: the first is a new crystalline getter, based on 1,4-bis(phenylethynyl)benzene{sup 5} (DEB); the second is a polymeric hydrogen getter, basedmore » on styrene-butadiene copolymer.« less

Hydrogen-tritium getters and their applications

Abstract: The accumulation of hydrogen is usually an undesired event Large leaks from hydrogen storage and handling facilities pose explosion hazards Small amounts of hydrogen that may build up in sealed containers after long storage times can damage internal components Any tritium leak is an immediate health hazard Hydrogen scavengers or getters can avert all of these potential problems by irreversibly removing hydrogen from such environments Early hydrogen getters were metals that, though effective, were sensitive to oxygen More recent work with crystalline organic materials has yielded formulations that will scavenge hydrogen in the presence or absence of air They commonly utilize a catalyst to add hydrogen across of carbon-carbon double or triple bond Because of the instability of organic materials to ionizing radiation, a getter that will be stable after reaction with tritium is a further challenge We will describe hydrogen getter materials and systems developed at Sandia National Laboratories and at Allied-Signal, Kansas City Division These materials have the proven ability to scavenge and contain hydrogen and tritium The technologies are based on the irreversible removal of hydrogen by catalytic hydrogenation of unsaturated organic compounds 6 refs

Catalytic hydrogen storage electrode materials for use in electrochemical cells incorporating the materials

Abstract: Describes a reversible electrochemical cell (10) having an electrode (12) negative hydrogen storage with high electrochemical activity. The negative electrode consists of an alloy of reversible electrochemical storage of hydrogen, multicomponent, multiphase. The hydrogen storage alloy can load and unload electrochemically hydrogen in alkaline aqueous media. In another preferred example, the hydrogen storage alloy is a member of the family of hydrogen storage alloys, derived from the alloys Ti-V-Zr-Ni-Cr and V-Ti-Zr-Ni Cr, in which the V, Ti, Zr, Ni and Cr are partially replaced by one or more modifiers, and the alloy has the composition: (Vy'-yNiyTix'-xZrxCrz) aM'bM''cM '' 'dM '' '' e, wherein x 'is between 1.8 and 2.2, x is between 0 and 1.5, y' is between 3.6 and 4.4, y is 0, 6 and 3.5, z is between 0.00 and 1.44, has means that the V-Ni-Ti-Zr-Cr component as a group represents an atomic percentage of between 70 and 100 alloy , b, c, d, e, ..., are the coefficients applicable modifiers and M ', M' 'and Mi are modifiers that can individually and collectively represent up to 30 atomic percent of the total alloy . Modifiers and M ', M' ', Miii and Miv are modifiers that can individually or collectively represent an atomic percentage of up to 30 of the total alloy. Modifiers, M ', M' ', Mii and Miv are chosen from A1, Mn, Mo, Cu, W, Fe, Co, Si, Sn, Zn and combinations thereof.

Hydrogen storage electrode

Abstract: PURPOSE: To improve the charge/discharge life of an alloy and improve the discharge characteristic at a high rate and a low temperature by constituting an electrode with a specific hydrogen storage alloy. CONSTITUTION: A hydrogen storage electrode is constituted of a hydrogen storage alloy indicated by a formula A 1-α Ni 5-y-2 CoyMz, where A is rare earth elements, their mixture or a mixture of rare earth elements and Zr, Hf, M is Al, Mn or their mixture, 0<α<0.06, y=0.3-1.2, z=0.2-1.2. The high-rata discharge characteristic and low-temperature discharge characteristic can be improved while the cycle life of the alloy is maintained. COPYRIGHT: (C)1991,JPO&Japio

Manufacture of metal-hydrogen alkaline storage battery

Abstract: PURPOSE:To increase the discharge operating voltage and improve the battery characteristic by assembling a battery with a positive electrode, a negative electrode made of a hydrogen storage alloy electrode and an alkaline electrolyte, then applying the discharge treatment with preset deep depth. CONSTITUTION:A positive electrode made of a sintered nickel electrode, a negative electrode made of a hydrogen storage alloy electrode and an alkali- resistant separator are wound into a spiral electrode body, it is inserted into a battery can, an alkaline electrolyte is injected, and an opening is sealed to assemble a battery. The battery is charged as required, then the discharge treatment is applied nearly completely so that the discharging current is continuously decreased until the discharge stop voltage becomes 0.3-1.0V. The hydrogen stored in the hydrogen storage alloy easily permeate or break an oxide film formed on the surface of the alloy via the deep discharge, and the activity of the negative electrode is improved. A metal-hydrogen alkaline storage battery using the hydrogen storage alloy as the negative electrode and having increased discharge operating voltage and improved battery characteristic is obtained.

Cryogenic equipment of liquid hydrogen powered automobiles.

Abstract: A possible consequence of the dramatic changes taking place within the global atmosphere because of uncontrolled consumption of fossil energy resources, is the eventual substitution of hydrocarbon fuels of our present transportation systems by pure hydrogen. Future hydrogen powered vehicles are most likely to use liquified cryogenic gas because of its superior storage efficiency compared to other hydrogen storage techniques. The paper describes the development and state of the art of mobile cryogenic storage tanks and supply systems currently realized in experimental hydrogen vehicles. Special attention is focussed on the design and performance of the liquid hydrogen vessel including the on-board installations for control and operation as well as the necessary external refueling system.