Showing papers on "Hydrogen storage published in 1994"
TL;DR: In this article, measurements of hydrogen adsorption on commercially available and densified adsorbents were carried out in the pressure range 1 − 80 atm and at different storage temperatures using a high-pressure volumetric method.
239 citations
TL;DR: In this article, the electrochemical properties of amorphous Mg5oNi5o-;t-),MxN), (M, N = Co, Al and Si) hydrogen storage alloys prepared by mechanical alloying (MA) were investigated.
Abstract: The electrochemical behaviours of some amorphous Mg5oNi5o-;t-),MxN), (M, N = Co, Al and Si) hydrogen storage alloys prepared by mechanical alloying (MA) were investigated. It is found that the MA amorphous alloys are easier to activate electrochemically than crystalline alloys. All MA amorphous alloys reach their respective maximum capacities at the first charge/discharge cycle. At a current density of 20 mA/g the MA Mg5oNi5o has a maximum discharging capacity around 500 mAh/g, which is ten times higher than that of the crystalline alloy. The partial substitution of Co, Si and Al for Ni in Mg5oNi50 alloy decreases its discharging capacity each to a different extent. However, the durability of the amorphous Mg5oNi5o-:t-,,M.tN), alloys is rather poor, and their capacity degradation rates amount to 10
207 citations
TL;DR: In this paper, an ongoing collaboration among the authors in the three laboratories to (1) prepare alloys of the AB(sub 5) and AB (sub 2) types, using arc-melting/annealing and mechanical alloys techniques; (2) examine their physico-chemical characteristics (morphology, composition); (3) determine the hydrogen absorption/desorption behavior (pressure-composition isotherms as a function of temperature); and (4) evaluate their performance characteristics as hydride electrodes (charge/discharge, capacity retention, cycle
145 citations
TL;DR: In this paper, an indirect ammonia fuel cell system is proposed which circumvents the problem of hydrogen storage, and system analysis shows that the specific energy density (kWh/kg or kWh/m3) of such a system is very attractive compared with that of a direct hydrogen fuel cell.
124 citations
Patent•
28 Jun 1994
TL;DR: In this article, the reaction of alkali, alkali-earth metal hydride with water is utilized for the generation of hydrogen in a novel generator configuration, which is comprised of a structure of corrugated perforated sheet metal and several layers of water wicking material.
Abstract: The reaction of alkali, alkali-earth metal hydride with water is utilized for the generation of hydrogen in a novel generator configuration. This overcomes the problem associated with the expansion of the hydride upon its conversion to hydroxide or oxide when reacting with water encountered in prior art generators. The hydride cartridge is comprised of a structure of corrugated perforated sheet metal and several layers of water wicking material, which hydride granules has dispersed within it. The hydride cartridge is housed in a reactor to which liquid water is admitted in a controlled mode. As the water enters the reactor and reaches the cartridge, hydrogen is instantaneously generated by the hydride water reaction. The hydrogen generation continues as long as unreacted hydride remains and water is being admitted. The wicking material allows the reaction to proceed inasmuch as it overcomes the rate limiting effect of diffusion barriers which may develop as portions of the hydride granules are reacted. As the reaction proceeds, compression of the sheet metal corrugations of the cartridge structure accommodates the volumetric expansion associated with hydride expansion. The combination of the corrugated cartridge structure and the wicking material dispersed throughout the cartridge facilitate the complete utilization of the hydride and water in a demand responsive mode. The generator is utilizable where intermediate hydrogen storage is impractical, e.g., for electric power generation in fuel cells generally and for underwater vehicles to overcome space restraints.
76 citations
TL;DR: In this article, a new composite hydrogen storage material with high storage capacity and favorable absorption-desorption kinetics has been successfully synthesized for Mg-40% FeTi composite alloys.
63 citations
TL;DR: In this paper, a self-protective mechanism for overdischarge of the hydrogen battery is described, where the hydrogen produced on the nickel electrode is absorbed on the MH electrode and then oxidized to water, keeping the cell voltage around 0.2 V.
Abstract: — 2 times higher energy density per unit volume and longer cycle life than Ni —Cd cells with almost comparable rate capability and charge retention. A very unique feature of the hydrogen battery is a self-protective mechanism for overdischarge. The hydrogen produced on the nickel electrode is absorbed on the MH electrode and then oxidized to water, keeping the cell voltage around —0.2 V. No oxidation and degradation of alloy occurs during overdischarge if the recombination reaction is fast enough to keep up with the discharge rate. This good overdischarge protection is very advantageous for the series stacking of many cells, i.e., for high voltage applications such as electric vehicles (EV) [6]. Secondly, AB5 (A = rare earth, Zr, B = Ni, Co, Fe, Mn, Al) and AB2 (A = Ti, Zr, B = Ni, V, Fe, Co, Mn, Al) type alloys do not contain hazardous materials, being safe from the standpoint of environmental and safety regulations [7].
62 citations
Patent•
07 Oct 1994TL;DR: In this paper, a method and apparatus for converting energy to hydrogen gas using an electrolyzer and a metal alloy hydride tank for hydrogen storage is described, where a passive load matching device between the energy source and the electrolyzer maximizes hydrogen output.
Abstract: This invention relates to a method and apparatus for converting energy to hydrogen gas using an electrolyzer and a metal alloy hydride tank for hydrogen storage, wherein a passive load matching device between the energy source and the electrolyzer maximizes hydrogen output, and the electrolyzer and the metal alloy hydride tank operate at mutually low pressure, near ambient, such that pressurization of the system is not required.
58 citations
Patent•
27 Jun 1994
TL;DR: An apparatus for storing hydrogen gas within an enclosed metal hydride container that is isolated from an apparatus which uses hydrogen gas, including a constricted opening having a valve to selectively open or close the hydrogen gas communication between the hydrogen storage container and the apparatus using the hydrogen.
Abstract: An apparatus for and method of storing hydrogen gas within an enclosed metal hydride container that is isolated from an apparatus which uses hydrogen gas, including a constricted opening having a valve to selectively open or close the hydrogen gas communication between the hydrogen storage container and the apparatus using the hydrogen. Also included within the hydrogen gas communication between the storage and use is a filter for filtering out oxygen and water vapor molecules from the hydrogen stream passing from the apparatus using the hydrogen to the hydrogen storage metal hydride. The filter means comprises a thin metal disc or a hydrogen gas permeable elastomeric thin film coating, such as a polyethylene resin or silicone oil, either in the hydrogen stream path or as a coating on each of the hydrogen absorbing metal hydride particles which are disposed within the hydrogen storage chamber. The enclosed metal hydride container may be disposed either within the apparatus using the hydrogen gas or externally thereof.
36 citations
TL;DR: In this article, the activation treatment of FeTi gives rise to the precipitation of Fe-rich clusters close to its surface and these clusters catalyse the decomposition of molecular hydrogen.
35 citations
TL;DR: In this article, numerical simulations are used to get a closer insight into the transient response behavior of these elegant, but rather complicated systems during variable insolation conditions and to estimate the overall system performance accurately over extensive periods of time.
TL;DR: In this paper, a theoretial approach for modelling storage capacities is presented, pointing out limiting parameters, and the same approach is used to study the recovery of hydrogen, first at a given temperature, and secondly at a required flow rate.
TL;DR: A hydrogen storage alloy electrode comprising, an electrically conductive support made of a punched or perforated metal sheet, a mixture supported on said conductive supports and a water-repellent agent for giving a water repellent property on the surface of the electrode, said mixture including; a hydrogen storage alloys powder, a styrene-butadiene copolymer having an styrene to butadiene weight ratio in a range of 100:30 to 100:100 as a binder, a polymeric material for giving hydrophilic property inside the electrode and
TL;DR: In this paper, the PCT curve of hydrogen storage alloys has been studied and the calculated PCT curves are in good agreement with the experimental curves, and a lot of physical parameters, which are very useful, can be estimated from the modeling.
TL;DR: In this article, the authors synthesized new composite particles for hydrogen storage on the basis of an idea of "particle designing", where powders of Mg and YNi2 were selected.
TL;DR: In this article, the authors studied BaReH{sub 9} with respect to hydrogen storage because it has the highest known H/M ratio and characterized the structure by infrared spectroscopy, NMR, and X-ray diffraction.
Abstract: The authors studied BaReH{sub 9} because of interest with respect to hydrogen storage because it has the highest known H/M ratio. The structure was characterized by infrared spectroscopy, NMR, and X-ray diffraction.
TL;DR: In this article, the principles of fuel cells are discussed, underlining electrocatalytic problems to be overcome to increase their energy efficiency, and power density, and different kinds of fuel cell are then presented, with their advantages and disadvantages, and their possible uses, particularly as power sources for electric vehicles.
Abstract: After a short historical survey, the principles of fuel cells are discussed, underlining electrocatalytic problems to be overcome to increase their energy efficiency, and power density. The different kinds of fuel cells are then presented, with their advantages and disadvantages, and their possible uses, particularly as power sources for electric vehicles. Different means of fuel and hydrogen storage are also discussed. Finally the two types of fuel cells, which appear the best candidates for an electric vehicle, are presented in details, i.e. the H 2 /air Proton Exchange Membrane Fuel Cell, and the Direct Methanol/air Fuel Cell
TL;DR: In this article, various types of metal hydrides are defined and various applications of these materials such as hydrogen storage, rechargeable batteries, hydrogen compressors, heat storage and heat pumps, isotope separation and hydrogen purification are briefly described.
Patent•
04 Apr 1994TL;DR: An improved metal hydride hydrogen storage alloy electrode (20) for use in an electrochemical cell was proposed in this article, where the improved electrode included a hydrogen storage Alloy material (22) having a layer of a passivation material disposed thereon.
Abstract: An improved metal hydride hydrogen storage alloy electrode (20) for use in an electrochemical cell (10). The improved electrode (20) includes a hydrogen storage alloy material (22) having a layer of a passivation material (25) disposed thereon.
Patent•
28 Oct 1994TL;DR: In this paper, a sealed storage battery for use in potable power supply is improved by using metal oxide-hydrogen storage alloy to have a higher capacity and a smaller weight, where the battery has a structure which comprises a combination of a positive electrode having a high energy density in a wide range of temperature and consisting of a bulk high porosity body filled with an active material composed of solid solutions such as typical Co solid solution, oxide powders such as typically Ca(OH)2 and ZnO, with an addition of graphite for rendering the electrode reaction effective.
Abstract: A sealed storage battery for use in potable power supply is improved by using metal oxide-hydrogen storage alloy to have a higher capacity and a smaller weight. The battery has a structure which comprises a combination of a positive electrode having a high energy density in a wide range of temperature and consisting of a bulk high porosity body filled with an active material composed of solid solutions such as typical Co solid solution, oxide powders such as typically Ca(OH)2 and ZnO, with an addition of graphite for rendering the electrode reaction effective; and a high capacity negative electrode of hydrogen storage alloy having a reduced equilibrium hydrogen pressure, and where the aforementioned characteristics at high temperatures are further enhanced by an electrolyte suitable to high temperatures, short-circuits are prevented by a chemically stable separator, and a structure sealing a container and a safety vent is excellent in air-tightness and reliability.
TL;DR: In this paper, the composite alloys La 2 Mg 17 - x wt% LaNi 5 and Mg-xwt% FeTi(Mn) have been successfully synthesized and the hydriding behaviors of these materials were studied for various values of x.
TL;DR: In this article, two prototypes were developed for different capacities and kinetics of hydrogen storage as hydrides: single tube (ST) and multitube (MT) models, and the results showed that the ST model resulted in better kinetics for hydrogen absorption-desorption, lower cost, and more reliable operation than the MT model.
TL;DR: In this article, the characteristics of filling microballoons with hydrogen, storage and extraction of hydrogen are discussed, and a comparison with other known methods for storing hydrogen when it is being used as an energy carrier is cited.
TL;DR: In this article, the performance of the negative electrode was evaluated with various electroless Ni-P and Ni-B coatings to improve the discharge capacity and high-rate dischargeability.
Abstract: Multicomponent hydrogen storage alloy with the composition MmNi3.31Mn0.37Al0.28CO0.64 (Mm = misch metal consisting of 24.87% La, 52.56% Ce, 5.57% Pr, 16.86% Nd and 0.14% Sm) was used as a negative electrode material. To improve the performance of the negative electrode, the alloy particles were modified with various electroless Ni-P and Ni-B coatings. Electrochemical properties such as discharge capacity and high-rate dischargeability of the negative electrode were generally improved by the surface modifications. However, in the case of a Ni-P (10 wt % P) coating, the discharge capacity and high-rate dischargeability decreased with increasing thickness, due to the low hydrogen permeability and high electric resistivity of the coating. Consequently, both kinds of coating and their thickness are critical factors in determining the performance of such a negative electrode.
TL;DR: In this paper, a method for manufacturing hydrogen storage alloy particles comprises steps of obtaining a melt of the hydrogen storage mixture and pulverizing the mixture by water atomizing process, whereby the melt is pulverized by contacting or colliding with high-speed jetting to be dispersed in the form of solidified fine particles.
TL;DR: In this paper, the authors analyzed the electrochemical hydrogen desorption process from metal hydride electrodes in terms of the model presented in Part 1 and showed that hydrogen is transferred more easily from the absorbed to the adsorbed state than in the opposite direction.
Abstract: The electrochemical hydrogen desorption process from metal hydride electrodes is discussed in terms of the model presented in Part 1. Based on the previously obtained equations, quantitative numerical calculations are presented for the near-surface concentration of hydrogen during electrochemical desorption from H-storing materials. The time dependence of H concentration is discussed in terms of the size and shape of the host (plates, cylinders, or spheres), to analyze the results obtained for ribbon, fiber, and powder of electrodes. Experimental data are presented concerning the anodic overpotential decay during galvanostatic discharge of several hydride electrodes in ribbon and powder form. The data are fit by the theoretical model and the values of the parameter characterizing the discharge process are determined. These include the interface hydrogen transfer coefficient, K[sub t], the reaction transition time, [tau][sub r], as well as the symmetry coefficient for the electrochemical oxidation, [beta]. K[sub t] is positive in most of the investigated cases, showing that hydrogen is transferred more easily from the absorbed to the adsorbed state than in the opposite direction. For a crystalline host showing a phase transformation, the model may be applied only in the single-phase regions, i.e., at the beginning and the end of themore » discharge process.« less
TL;DR: In this paper, the authors presented conceptual designs for fuel cell-based air independent propulsion (AIP) plugs that could be retrofitted to an ocean-going conventional submarine of about 3 000 t displacement.
Patent•
14 Mar 1994
TL;DR: In this paper, a hydrogen storage material capable of efficiently absorbing and desorbing hydrogen at ordinary temps was obtained and capable of occluding a large amt. of hydrogen.
Abstract: PURPOSE:To obtain a hydrogen storage material capable of efficiently absorbing and desorbing hydrogen at ordinary temps. and capable of occluding a large amt. of hydrogen. CONSTITUTION:The material is expressed by Ti100-x-y-zCrxAyBz, where A is >=1 kind among V, Nb, Mo, Ta and W, B is >=2 kinds among Zr, Mn, Fe, Co, Ni and Cu, 0 =0.33Angstrom . Consequently, a large amt. of hydrogen is occluded at ordianry temps., and hydrogen is economically and practically stored and transported.
Patent•
18 Feb 1994TL;DR: In this paper, a composite hydrogen storage alloy material consisting of a hydrogen storage mixture and a surface material bonded to the surface of the mixture has been proposed to allow the migration of hydrogen between the inside and outside of the composite material.
Abstract: A composite hydrogen storage alloy material includes a hydrogen storage alloy material and a surface material bonded to the surface of the hydrogen storage alloy material. The surface material has a potential energy between those of hydride of the hydrogen storage alloy and hydrogen gas and permits migration of hydrogen between the inside and outside of the hydrogen storage alloy material.
TL;DR: In this article, a global model for the performance of the dehydrogenation reactor is developed, which combines the kinetic models for the MCH deactivation, and for the deactivation of the industrial Pt-Sn/Al 2 O 3 catalyst, and the bidimensional model for a tubular reactor.