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Hydrogen Storage
(Released June 2001)

  by Laura Becker  


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  1. Materials for rechargeable batteries and clean hydrogen energy sources

    Wronski, ZS

    International Materials Reviews (USA), vol. 46, no. 1, pp. 1-49, 2001

    Materials for energy sources, such as rechargeable batteries and fuel cells, are functional materials. Their development presents special challenges since they are designed for more than one function and must satisfy multiple and mostly interlocking requirements. A unique combination of properties is achievable in complex structures such as functional composites, multi-element and multiphase intermetallics, cermets, layered insertion compounds, and new nanostructured and disordered phases. This review deals with a variety of such materials being developed for use in clean energy storage, which is mostly, but not entirely, hydrogen energy storage. The scope of the work encompasses hydrogen gas storage alloys and intermetallics used for electrochemical hydrogen storage, insertion compounds for Li batteries, and ceramics and metal catalysts for fuel cells. It also includes materials used in lead-acid, nickel metal hydride, and lithium rechargeable batteries as well as in solid oxide, proton exchange membrane, and direct methanol fuel cells. Special topics highlight new nanostructured materials obtained by rapid quenching, mechanical alloying, and other processes. The review is complemented by a brief discussion of present trends in assessment of materials requirements for batteries and fuel cells for electric vehicles and portable telecommunication. Also addressed are aspects of recycling and life-cycle analysis.

  2. Degradation of hydrogen absorbing capacity in cyclically hydrogenated TiMn sub 2

    Semboshi, S; Masahashi, N; Hanada, S

    Acta Materialia (USA), vol. 49, no. 5, pp. 927-935, 14 Mar. 2001

    Degradation of the hydrogen absorbing capacity in cyclically hydrogenated TiMn sub 2 (Ti-60 at.% Mn) with Laves structure was studied by measurement of pressure-composition-isotherm (PCT) curves, x-ray diffraction and microstructure observation. Characteristic changes with cyclic hydrogenation are observed as follows. The hydrogen absorbing capacity remarkably decreases, the lattice constant increases, the amount of hydrogen retained in TiMn sub 2 increase and it approaches almost zero by dehydrogenation at 673K in vacuum. Nano-sized regions with Moire patterns are produced in TiMn sub 2 with hydrogenation and Debye rings corresponding to titanium hydride delta -TiH appear in the diffraction pattern. Based on these observations it is concluded that the degradation of hydrogen absorbing capacity after cyclic hydrogenation is attributable to the introduction of retained hydrogen, heterogeneous strain and/or nano-sized regions.

  3. Activity and capacity of hydrogen storage alloy Mg sub 2 NiH sub 4 produced by hydriding combustion synthesis

    Li, L; Akiyama, T; Yagi, J-I

    Journal of Alloys and Compounds (Switzerland), vol. 316, no. 1-2, pp. 118-123, 2 Mar. 2001

    A high activity and a large capacity of hydrogen storage alloy Mg sub 2 NiH sub 4 produced by hydriding combustion synthesis were investigated by means of differential scanning calorimeter (DSC) and pressure-composition isotherms (PCT). The results showed that the product of Mg sub 2 NiH sub 4 from the hydriding combustion synthesis has enough activity to the hydriding reaction and the amount of hydrogen absorbed by the product reached the maximum (3.4-3.6%) mass near the theoretical value just after synthesis without any activation process. This kind of activity and capacity of hydrogen storage are not only stable, but also tolerant of high temperature of 850 K. PCT results give some phenomenon of three phases existing in isotherms. The relationships between the equilibrium plateau pressure and the temperature were Log P (0.1 MPa)=- 3525/T+6.667 for hydriding and Log P (0.1 MPa)=-3724 /T+6.883 for dehydriding.

  4. Simple model for discharge capacity of Ti-Mn based alloys

    Zhang, Y., -; Guo, SW; Liu, Y.-N., --

    Chinese Journal of Nonferrous Metals (China), vol. 11, no. 1, pp. 79-83, Feb. 2001

    In view of bad cycle stability of Ti-Mn based alloys, a simple model for the cycle life of Ti-Mn hydrogen-storage alloys was give. Two factors were introduced to indicate the intrinsic characteristic of hydrogen-storage metal: active factor, beta , and capacity-degrade factor, A. The model can describe the whole process of activation and degradation. The activation and cycle process of two alloys: Ti sub 0.26 Zr sub 0.07 Vo sub 0.21 Mn sub 0.1 Ni sub 0.3 Cr sub 0.03 and Ti sub 0.26 Zr sub 0.07 V sub 0.19 Mn sub 0.1 Ni sub 0.3 Cr sub 0.05 were measured and the results agreed with the theory well.

  5. Crystal structure and electrochemical properties of Zr(Mn sub 1-x Ni sub x ) sub 2 (0.40<=x<=0.75) hydrogen storage alloys

    Zhang, WK; Ma, CA; Yang, XG; Huang, H; Lei, YQ; Wang, QD

    Acta Metallurgica Sinica (English Letters) (China), vol. 14, no. 1, pp. 56-62, Feb. 2001

    The crystal structure, phase abundance and the electrochemical properties of Zr(Mn sub 1-x Ni sub x ) sub 2 (0.40<=0.75) alloys were investigated by means of XRD, Rietveld refinement method and electrochemical measurements. The alloys are multiphase. C15 Laves phase occurs as a main phase accompanying with C14 phase and other minor phases, indicating that Ni element is C15-stabilized element for ZrMn sub 2 alloy. The phase abundance and lattice parameters of Laves phase are influenced significantly by Ni substitution. The Zr(Mn sub 0.45 Ni sub 0.55 ) sub 2 alloy with the highest amount of C15 phase exhibits the maximum electrochemical capacity of 242 mAh/g. C14 phase occurring in Zr-Mn-Ni alloys is beneficial for the electrochemical kinetics of hydride electrodes.

  6. High temperature charging efficiency and degradation behavior of high capacity Ni-MH batteries

    Choi, J., -; Kim, IJ

    Metals and Materials (South Korea), vol. 7, no. 1, pp. 77-81, Feb. 2001

    Recently the Ni/MH secondary battery has been studied extensively to achieve higher energy density, longer cycle life and faster charging-discharging rate for electric vehicles and portable computers, and etc. In this work, the charging efficiency of the Ni-MH battery which uses Ni electrode with addition of various compounds and the degradation behavior of the 90Ah battery were studied. The battery using the Ni electrode with Ca(OH) sub 2 addition showed the charging efficiency and the utilization ratio significantly better than electrodes without added compounds. After 418 cycles, the residual capacities at the Ni electrode showed nearly the same values in the upper, middle and lower regions. In the case of the MH electrode, the residual capacity in the upper reigon appeared lower than that in other regions. As a result of ICP analysis, the amount of dissolved elements in the three regions appeared almost the same. The faster degradation in the upper region of the MH electrode was caused by the TiO sub 2 oxide film formed at the electrode surface because of overcharging. The thickness of the oxide film increases with cycling, so it will form a layer that is not able to allow hydrogen to penetrate into the MH electrode.

  7. Hydrogen storage material based on LaNi sub 5 alloy produced by mechanical alloying

    Simicic, MV; Zdujic, M; Jelovac, DM; Rakin, PM

    Journal of Power Sources (Switzerland), vol. 92, no. 1-2, pp. 250-254, Jan. 2001

    The electrochemical characteristics of the La sub 0.8 Ce sub 0.2 Ni sub 2.5 Co sub 1.8 Mn sub 0.4 Al sub 0.3 compound, produced by mechanical alloying, are investigated for hydrogen storage in nickel-metal hydride (NiMH) batteries by discharging tests at constant current and by calculating equilibrium pressure of hydrogen from the equilibrium potentials. It is shown that the alloy produced by mechanical alloying, followed by annealing and activation exhibits high specific capacity at the stable potential plateau, even at the high discharge rate (10 mA cm exp -2 ), and low hydrogen equilibrium pressure. The alloy of such composition gives low capacity loss during cycling, which enables its application for metal hydride battery production.

  8. A novel method to improve the electrochemical properties of hydrogen storage electrode alloy

    Ma, J; Pan, H; Zhu, Y; Li, S; Chen, C

    Acta Metallurgica Sinica (China) (China), vol. 37, no. 1, pp. 57-60, 18 Jan. 2001

    A magnetization treatment was proposed firstly to improve the electrochemical properties of hydrogen storage electrode alloy in this paper. The results indicate that through the magnetization treatment, the electrochemical properties of hydrogen storage permanent magnet electrode alloy La sub 0.9 Sm sub 0.1 Ni sub 5.0-y Co sub y (y=2.0,2.5,3,0), including electrochemical capacity, cycle life and the high-rate dischargeability, can be improved to some extent. Furthermore, the effect of magnetization treatment on its electrochemical properties is related to the content of Co. The more the cobalt content is, the higher the magnetization effect is.

  9. Effect of Ni encapsulation on the properties of Ti-Zr-based hydrogen storage alloys

    Chuang, HJ; Chan, SLI

    Journal of Alloys and Compounds (Switzerland), vol. 314, no. 1-2, pp. 224-231, 16 Jan. 2001

    Effects of Ni encapsulation on the electrochemical properties of a Ni-free alloy have been studied in this work. The encapsulation was by means of electroless nickel plating of the alloy powders either in an acidic or a basic solution. It was found that Ni encapsulation not only enhanced the discharge capacity, but also increased the activation rate. A Ni-P encapsulated Ti sub 0.5 Zr sub 0.5 Mn sub 1 Cr sub 1 alloy showed a discharge capacity of 175 mAh/g, which was 9 times better than that of the as-pulverized alloy (17 mAh/g). However, this discharge capacity was deteriorated by a heat treatment at 750 deg C for 62 h. This damaging effect was resulted from Ni migration into the alloy matrix during heat treatment. SEM, EPMA and XRD results indicated that a complicated diffusive layer was formed around the particle surface with a crystal structure different from C14, which inhibited the charge-discharge reactions. The thickness of this diffusive layer increased with the temperature of heat treatment, and was more significant for the Ni layer coated in an acidic solution.

  10. Study on the electrode characteristics of hypostoichiometric Zr-Ti-V-Mn-Ni hydrogen storage alloys

    Lee, SM; Kim, S.-H., --; Jeon, S.-W., --; Lee, J.-Y., --

    Journal of the Electrochemical Society (USA), vol. 147, no. 12, pp. 4464-4469, Dec. 2000

    The hydrogen storage performance and electrochemical properties of Zr sub 1-X Ti sub X (Mn sub 0.2 V sub 0.2 Ni sub 0.6 ) sub 1.8 (X = 0.0, 0.2, 0.4, 0.6) alloys are investigated. All of these alloys have mainly a C14-type Laves phase structure according to X-ray diffraction analysis. As the mole fraction of Ti in the alloy increases, the reversible hydrogen storage capacity decreases, while the equilibrium hydrogen pressure increases. Furthermore, the discharge capacity shows a maximum and the rate capability is increased, but the cycling durability is rapidly degraded with increasing Ti content in the alloy. The analysis of surface composition shows that the rapid degradation of Ti-substituted Zr-based alloy electrodes is due to the growth of an oxygen penetration layer. After comparing the radii of atoms and ions in the electrolyte, it is clear that the electrode surface becomes more porous, which is the source of growth of the oxygen penetration layer and causes accelerating the dissolution of alloy constituting elements with increasing Ti content. Consequently, the rapid degradation (fast growth of the oxygen-penetrated layer) with increasing Ti substitution in Zr-based alloy is ascribed to the formation of a porous surface oxide through which the oxygen atom and hydroxyl ion, with relatively large radii can easily transport into the alloy surface.

  11. Carrying clean energy to the future--hydrogen absorbing materials

    Guo, ZX; Bououdina, M

    Materials Technology (UK) (UK), vol. 15, no. 4, pp. 269-275, Dec. 2000

    Hydrogen is very promising as a clean and renewable fuel for transportation and energy storage. The major challenges in the development of new hydrogen storage materials, with particular reference to batteries and fuel cells, are much improved energy storage density, kinetics, cycle life and ready availability at reduced cost. Many studies have been devoted to the increase of the storage capacity by alloying modifications, whereas kinetics were improved via both alloying and processing, such as mechanical alloying and melt spinning. Different categories of intermetallic compounds have been studied such as LaNi sub 5 and TiFe compounds, Zr- and Ti-based Laves phases, Mg sub 2 Ni and Mg based materials, and composites. Recently, carbon nanotubes and sodium alanates have also attracted attention as promising materials for hydrogen storage. This report outlines the pros and cons and promises of these groups of materials, with an aim of providing a balanced view of this rapidly developing technology.

  12. Gas atomization of metal hydrides for Ni-MH battery applications

    Anderson, IE; Anderson, ML

    Journal of Alloys and Compounds (Switzerland), vol. 313, no. 1-2, pp. 47-52, 15 Dec. 2000

    The use of high pressure gas atomization (HPGA) to produce fine, spherical powders of metal hydride (MH) alloys has been shown to improve the properties of the alloy, as well as reducing costly processing steps. Electrochemical cycling was used to compare three electrodes constructed of LaNi sub 4.75 Sn sub 0.25 particulate, a simplified AB sub 5 -type alloy for battery applications. Two electrodes consisted of gas atomized powders and the other used particulate produced from casting and crushing an ingot, the conventional method of MH particulate production. Gas atomized powders showed improved cyclic stability over the cast and crushed particulate. A commercial cast and crushed MmNi sub 3.55 Co sub 0.75 Mn sub 0.4 Al sub 0.3 alloy was also cycled and showed reduced degradation when compared against the electrode composed of LaNi sub 4.75 Sn sub 0.25 cast and crushed particulate, as was expected.

  13. Pulse activation of hydrogen-storage alloy electrodes in nickel /metal hydride batteries

    Wu, MS; Wang, Y.-Y., --; Wan, C.-C., --

    Journal of the Electrochemical Society (USA), vol. 147, no. 11, pp. 4065-4070, Nov. 2000

    Both pulse-potential and pulse-current processes were employed to activate hydrogen-storage alloy electrodes. Parameters that affect the electrode activation and capacity were investigated. In the pulse-potential process, the electrode showed fairly good activation and high discharge capacity when the hydriding and dehydriding potentials were set at -1.2 and -0.8 V, respectively, with respect to an Hg/HgO electrode. Similar results were found in the pulse- current process, for which applicable hydriding and dehydriding currents were 400 and 200 mA g exp -1 , respectively. An increase in total pulse time was not only useful for activation but also beneficial to the discharge capacity. The time interval had little effect on the electrode capacity but significantly influenced the activation process. A longer ratio of t sub on /(t sub on + t sub off ) enhanced the electrode maximum capacity but retarded activation. An appropriate ratio of t sub on /(t sub on + t sub off ) for pulse-potential was 0.5, and for pulse-current it was 0.83. In addition, the cycle-life stability and high-rate discharge capability of pulsed electrodes were superior to those of untreated electrodes. Alloy studied: Ti sub 0.35 Zr sub 0.65 Ni sub 1.2 V sub 0.6 Mn sub 0.2 Cr sub 0.2 .

  14. Hydrogen-absorbing alloys containing rare-earth elements and their applications

    Higashiyama, N; Yonezu, I

    Minerals, Metals and Materials Society/AIME, Second International Conference on Processing Materials for Properties (USA), pp. 929-932, Nov. 2000

    Hydrogen-absorbing alloys containing rare-earth elements are used in high capacity nickel-metal hydride secondary batteries, hydrogen storage systems for portable fuel cells, and refrigeration systems. New hydrogen-absorbing alloys containing rare-earth elements have also been developed and introduced into these applications. High performance in nickel-metal hydride secondary batteries is strongly demanded because of the remarkable advancements in portable electric appliances. A large hydrogen absorption capacity, high electrochemical reactivity and superior corrosion resistance in an alkaline solution are required for hydrogen-absorbing alloys used in nickel-metal hydride batteries. The aim of this investigation is to improve the performance of conventional LaNi sub 5 type hydrogen-absorbing alloys. For example, Mm(Ni-Co-Al-Mn) sub x type hydrogen-absorbing alloys with various non-stoichiometric compositions were developed. In addition, a new process of rapid quenching process was applied for preparing these hydrogen-absorbing alloys in order to improve their performance.

  15. Flake metal powder for nickel hydrogen battery

    Yushinaga, H

    Kogyo Zairyo (Engineering Materials) (Japan), vol. 48, no. 11, pp. 39-43, Nov. 2000

    The cathode of nickel hydrogen battery is made of hydrogen storage alloy powders. The preparation of flake metal powders is introduced. The influence of heating temperature of flake Ni powders on the discharge capacity and cycle number of hydrogen storage electrode is examined. The comparison of discharge capacity and cycle number of Ni anodes made by flake Ni powder and conventional method is made. The development of fabrication method of electrodes is presented.

  16. Low-Co rare-earth-based hydrogen storage alloy

    Li, QA; Sang, G., -; Li, JW; Chen, Y.-G., --; Tu, M.-J., --; Li, N., -

    Transactions of the Nonferrous Metals Society of China (China), vol. 10, no. 5, pp. 660-665, Oct. 2000

    On the basis of typical high-Co Ml (Lanthanum-rich mischmetal)-based hydrogen storage alloy, a series of low-Co or Co-free alloys have been prepared by means of partial or full replacement of Co by a combination of other elements. The microstructures, p-c-T (pressure-concentration-temperature) characteristics and electrochemical properties under different charge-discharge conditions of the alloys have been investigated. Compared with the high-Co alloy, the low-Co or Co-free alloys ahve the lower hydrogen equilibrium pressure and discharge capacity, but have the nearly same high-rate and high temperature discharge capability, and better charge-discharge cycling stability. The reason is revealed by SEM, XPS and XRD results.

  17. Effects of AB5-type hydrogen storage alloy prepared by different techniques on the properties of MH/Ni batteries

    Li, R; Wu, JM; Wang, X.-L., --

    Journal of Alloys and Compounds (Switzerland), vol. 311, no. 1, pp. 40-45, 12 Oct. 2000

    The effects of hydrogen storage alloy prepared by different preparation techniques with composition Mm(NiCoMnAl) sub 5 on the properties of MH/Ni batteries have been investigated. Compared with as-cast alloy, as-quenched and as-quenched + annealed alloy could produce advantages to the battery in high rate dischargeability, internal pressure, cycle lifetime and internal resistance at beginning of cycles. Unfortunately, the rapidly quenched alloy slowed down the initial activation rate of the battery voltage, but after annealing, the rate would improve slightly. The influence of the alloy from different preparation techniques on the capacity and voltage of batteries is slight. The annealing would mainly improve the high rate dischargeability and depress the internal pressure contrasted with the as-quenched alloy. The differences can be ascribed to the change of phase and microstructure caused by different preparation techniques.

  18. Hydrogen storage properties of new ternary system alloys: La sub 2 MgNi sub 9 , La sub 5 Mg sub 2 Ni sub 23 , La sub 3 MgNi sub 14

    Kohno, T; Yoshida, H; Kawashima, F; Inaba, T; Sakai, I; Yamamoto, M; Kanda, M

    Journal of Alloys and Compounds (Switzerland), vol. 311, no. 2, L5-L7, 26 Oct. 2000

    The hydrogen storage properties of the new ternary system alloys, La sub 2 MgNi sub 9 , La sub 5 Mg sub 2 Ni sub 23 , La sub 3 MgNi sub 14 , were investigated. As a result, the negative electrode of the La sub 5 Mg sub 2 Ni sub 23 alloy (La sub 0.7 Mg sub 0.3 Ni sub 2.8 Co sub 0.5 ) showed a large discharge capacity (410 mAh /g), 1.3 times larger than that of AB sub 5 type alloys. These ternary system alloys were found to be mainly composed of stacked AB sub 5 and AB sub 2 structure subunits in a superstructure arrangement.

  19. Electrochemical behaviour of nanostructured Mm(Ni,Al,Co) sub 5 alloy as MH sub x electrode

    Jurczyk, M; Majchrzycki, W

    Journal of Alloys and Compounds (Switzerland), vol. 311, no. 2, pp. 311-316, 26 Oct. 2000

    The electrochemical properties of nanocrystalline MmNi sub 3.5 Al sub 0.8 Co sub 0.7 alloy, which has the hexagonal CaCu sub 5 type structure, were investigated. This material was prepared by mechanical alloying (MA) followed by annealing and used as a negative electrode for a Ni-MH sub x battery. MA process transforms the starting mixture of the elements into an amorphous phase without other phase formation. Heating the MA sample at 1020 K for 0.5 h resulted in the formation of the hexagonal CaCu sub 5 -type structure. It was found that the electrodes prepared from the nanocrystalline powders had almost similar discharge capacities, compared with the negative electrode prepared from polycrystalline powders. In the annealed nanocrystalline MmNi sub 3.5 Al sub 0.8 Co sub 0.7 powders discharging capacities up to 135 mAh g exp - 1 (at 160 mA g exp -1 discharge current) were measured (note, that the lanthanum content in mischmetal was only 25 wt%).

  20. Hydriding-dehydriding characteristics of Mg sub 50 Ni sub 50-x Ti sub x alloys

    Sun, JC; Ji, S.-J., --; Li, Z.-H., --

    Chinese Journal of Nonferrous Metals (China), vol. 10, Suppl. 1, pp. 205-208, Oct. 2000

    The ability of amorphous formation and the hydriding-dehydriding characteristics of Mg sub 50 Ni sub 50-x Ti sub x alloys prepared by mechanical alloying method were investigated. When x = 1, 2, 5, 10, 15, the homogeneous single amorphous phase alloy can be obtained. The substitution of Ti element for Ni will decrease the equilibrium hydrogen pressure in MgNi-based alloys. Not only the small amount Ti-substituted alloys absorb more hydrogen in electrochemical conditions, but also those alloys show a higher durability in hydriding-dehydriding cycles. It is assumed that the function of Ti element is attributed to hindering magnesium from oxidation process.

  21. Preparation and characteristics of Zr sub (1-x) Ti sub x (NiCoMnV) sub 2.1 hydride alloy electrodes

    Wen, MF; Chen, L., -; Yu, B; Tong, M; Chen, DM; Zhai, Y.-C., --

    Huagong Yejin (Engineering Chemistry and Metallurgy) (China), vol. 21, no. 4, pp. 337-340, Oct. 2000

    Zr sub (1-x) Ti sub x (NiCoMnV) sub 2.1 hydrogen-storing alloy electrodes are prepared by adding nickel or carbon black conductor. Some electrodes are pre-treated by being charged in hot reducing agent. The discharge capacity is tested for each electrode. The results show that the properties of Zr sub (1- x) Ti sub x (NiCoMnV) sub 2.1 hydrogen-storing alloy electrode with nickel conductor are apparently better than those of electrode with carbon black. The performance of the electrode with nickel conductor and Ag additive with charging treatment in hot reducing agent is the best, the initial discharge capacity of this electrode can be up to 215 mA bullet h/g, and the plateau value about to 90%.

  22. Effect of yttrium on the corrosion of AB sub 5 -type alloys for nickel-metal hydride batteries

    Maurel, F; Leblanc, P; Knosp, B; Backhaus-Ricoult, M

    Journal of Alloys and Compounds (Switzerland), vol. 309, no. 1-2, pp. 88-94, 14 Sept. 2000

    The influence of Y sub 2 O sub 3 powder addition (as well as of rare earth oxides of Gd, Ho, Dy, Nd, Sm or Yb) to the metal hydride electrode on AB sub 5 alloy corrosion rates and on the chemical composition, morphology and density of the corrosion products was studied by X-ray, SEM, TEM and HRTEM. Adding Y sub 2 O sub 3 reduces the corrosion rate. This is particularly observed in the long-term behavior of the batteries and is more pronounced at higher temperature. When yttrium is added as an oxide to the electrode or electrolyte, it is dissolved in the electrolyte and is further incorporated as hydroxide in the corrosion scale. The decrease in the global alloy corrosion rate can be explained by a decrease of the driving force for diffusion of Mm exp 3- and OH exp - . Yb is the rare earth element which is expected to produce the largest decrease in corrosion rate, since its solubility in the electrolyte and its content in the corrosion scale are higher than for any other rare earth element. Electrode alloys studied: MmNiAlMnCo alloys.

  23. Hydrogen storage and electrode properties of V-based solid solution type alloys prepared by a thermic process

    Sakai, T; Tsukahara, M; Kamiya, T; Takahashi, K; Kawabata, A; Sakurai, S; Shi, J; Takeshita, HT; Kuriyama, N

    Journal of the Electrochemical Society (USA), vol. 147, no. 8, pp. 2941-2944, Aug. 2000

    A vanadium-based solid-solution-type alloy V sub 4 TiNi sub 0.65 Co sub 0.05 Nb sub 0.047 Ta sub 0.047 with a large discharge capacity was obtained using a low-cost precursor of V sub 4 Ni sub 0.65 Nb sub 0.047 produced by aluminothermic reduction from V sub 2 O sub 5 , Nb sub 2 O sub 5 , and Ni. The alloy was deoxidized to a low level by adding mischmetal as a reducing agent when the precursor was alloyed with Ti, Co, and Ta. The alloy showed a hydrogen absorption behavior similar to an alloy prepared from high-purity constituent metals. Moreover, the Mm-Ni-O phase was precipitated as spherical particles along the TiNi network phase in the alloy, remarkably improving the electrode rate capability because of enhanced catalytic ability of the network phase.

  24. Study on the development of hypo-stoichiometric Zr-based hydrogen storage alloys with ultra-high capacity for anode material of Ni /MH secondary battery

    Lee, JY; Lee, H., -; Kim, JH; Lee, P.S., -; Lee, SM

    Journal of Alloys and Compounds (Switzerland), vol. 308, no. 1-2, pp. 259-268, 10 Aug. 2000

    Some hypo-stoichiometric Zr-based Laves phase alloys were prepared and studied from a viewpoint of discharge capacity for electrochemical application. After careful alloy design of ZrMn sub 2 -based hydrogen storage alloys through changing their stoichiometry while substituting or adding some alloying elements, the Zr(Mn sub 0.2 V sub 0.2 Ni sub 0.6 ) sub 1.8 alloy reveals relatively good properties with regard to hydrogen storage capacity, hydrogen equilibrium pressure and electrochemical discharge capacity. In order to improve the discharge capacity and rate-capability, Zr is partially replaced by Ti. The discharge capacity of Zr sub 1-x Ti( sub x Mn sub 0.2 Y sub 0.2 Ni sub 0.6 ) sub 1.8 (x = 0.0, 0.2, 0.3, 0.4, 0.6) alloy electrodes at 30 deg C reaches a maximum value and decreases as the Ti fraction increases. In view of electrochemical and thermodynamic characteristics, the occurrence of a maximal phenomenon of the electrochemical discharge capacity of the alloy is attributed to a competition between decreasing hydrogen storage capacity and increasing rate-capability with Ti fraction. However, as the Ti fraction increases, the discharge capacity decreases drastically with repeated electrochemical cycling. Judging from the analysis of surface composition by Auger electron spectroscopy (AES), the rapid degradation with increasing Ti fraction in Zr-based alloy is ascribed to the fast growth of the oxygen-penetrated layer with cycling.

  25. Hydriding combustion synthesis mechanism of Mg-X (X=Fe, Co) hydrogen storage alloy

    Ohtsuji, T; Akiyama, T; Yagi, JI

    Journal of the Japan Institute of Metals (Japan), vol. 64, no. 8, pp. 651-655, Aug. 2000

    Magnesium-based alloys, Mg-Fe and Mg-Co, in particular, are very attractive as covalent or ionic hydrides for their large hydrogen storage capacity; 5.5 and 4.5 mass%, respectively. In a previous study, we produced pure Mg-X(X=Fe,Co) hydride successfully by combustion synthesis for the first time. However, in order to establish an industrial process, elucidation of the reaction mechanism for synthesizing the hydrides are needed. The aim of this study is to investigate the intermediate products during the combustion synthesis by using differential scanning calorimeter and x-ray diffraction analysis. Magnesium and iron or cobalt powders that are well mixed, and then compressed, are slowly heated up to 850K. These are cooled down to room temperature under hydrogen pressure of 7.0 MPa. The heat of reaction is monitored by DSC and intermediate products at the specified temperature are identifed by XRD. As a result, Mg absorbs hydrogen partially in the initial stage of heating, and then releasing it with the increase in temperature. This is common phenomenon for both systems. At high temperatures, Mg-Co and Mg-Fe systems showed different behavior. In the Mg-Co system, Mg sub 3 CoH sub 5 and Mg sub 2 CoH sub 5 are produced, dehydrided and reproduced, while no hydrogen absorption was found in the Mg-Fe system. It is supposed that the hydrides were synthesized directly from the mixture of metallic powders becuse no intermetallic compound was observed in both systems. Mg sub 2 FeH sub 6 , Mg sub 3 CoH sub 5 and Mg sub 2 CoH sub 5 were finally obtained by heating up and cooling down in hydrogen atmosphere. These results revealed the reaction mechanism for synthsizing Mg-X(X=Fe,Co) hydrogen storage alloy.

  26. Effects of some factors on the preparation of Zr-based AB sub 2 type laves phase hydrogen storage alloy

    Wen, M.-F., --; Zhai, Y.-C., --

    Huagong Yejin (Engineering Chemistry and Metallurgy) (China), vol. 21, no. 3, pp. 331-336, July 2000

    Ni-MH battery has a lot of advantages, such as high energy density, high rate capability, long cycle life and better environmental compatibility. It is important for preparing Ni-MH batteries to improve properties of Zr-based AB sub 2 type Laves phase hydrogen storage alloy. This paper reviews the effects of atom radium ratio, electronegativeness and constituent elements on the properties of Zr-based Laves phase hydrogen storage alloy, and the surface modification processes on the surface electrocatalytic and kinetic properties of electrodes.

  27. Effect of Cu powder as an additive material on the properties of Zr-based pasted alloy electrodes for Ni/MH batteries

    Lee, JY; Lee, H., -; Lee, PS; Yu, JS

    Journal of the Electrochemical Society (USA), vol. 147, no. 7, pp. 2494-2497, July 2000

    In order to investigate the effect of Cu powder as a conducting material on electrochemical performance, Zr-Ti-Cr-V-Mn-Ni alloy electrodes were prepared by pasting and carbon black powder was replaced by Cu powder. Electrode characteristics such as discharge potential, rate capability, and low-temperature discharge improved with the addition of Cu powder. The exchange current density increased and the reaction resistance decreased with increasing amounts of Cu powder. It is believed that the catalytic activity of the electrochemical hydriding reaction on the alloy was significantly improved by the substitution of Cu powder. Based on energy dispersive spectrometry analysis, the Cu concentration on the alloy surface dramatically increased after 350 cycles. This result indicates that a thin Cu layer forms on the alloy surface during cycling via a dissolution-precipitation mechanism. It is suggested that the thin copper layer on the alloy surface improves the electronic conductivity of the electrode and facilitates the hydriding reaction.

  28. Electrochemical characteristics of Al-substituted Mg sub 2 Ni As negative electrode

    Jianshe, X; Guoxun, L; Yaoqin, H; Jun, D; Chaoqun, W; Guangyong, H

    Journal of Alloys and Compounds (Switzerland), vol. 307, no. 1-2, pp. 240-244, 14 July 2000

    Amorphous Mg sub 2 Ni alloy powder was prepared by solid state-diffusion and subsequent mechanical grinding. The effect of partial substitution of Al for Mg on the electrochemical performances of Mg sub 2 Ni was investigated. The results show that Mg sub 2-x Al sub x Ni (x = 0.2, 0.3) has a long cycle life, up to 50 cycles at 200 mA/g discharge current density. It was found that the influence of Al, prolonging the cycle life, was mainly affected not by the discharge current density, but by the Al content. The mechanism of Al acting as an inhibitor of the corrosion was discussed.

  29. Method and an equipment for producing rapid condensation hydrogen storage alloy powder

    Inventor: Chen, Yu; Cai, Yun; Yu, Dongping; Dai, Xugeng. Patent Application Number: 029878. Date: 10 Jun 1998

    Patent Number US6174345

    The present invention relates to a method and apparatus of manufacturing nickel-metal-hydride alloy powder material. The furnace charge of nickel-metal-hydride alloy is melted in vacuum or argon atmosphere in this invention. After melting, the molten alloy is gas atomized to fine spherical powder or centrifugal atomized to flaky shape. Then the powders are fed into a hydrogen heat treatment chamber for hydrogen heat treatment and pulverization. This invention integrates the melting, pulverizing and hydrogen treatment of nickel-metal hydride alloy powder into a whole step. It can charge and pulverize continuously and is suitable for the large-scale industrialized production of homogeneous composition and least segregation nickel-metal hydride alloy powder.

  30. High storage capacity alloys enabling a hydrogen-based ecosystem

    Energy Conversion Devices, Inc. Inventor: Ovshinsky, Stanford R; Young, Rosa T. Patent Application Number: 435497. Date: 6 Nov 1999

    Patent Number US6193929

    Hydrogen propelled vehicles and fundamentally new magnesium-based hydrogen storage alloy materials which for the first time make it feasible and practical to use solid state storage and delivery of hydrogen to power internal combustion engine or fuel cell vehicles. These exceptional alloys have remarkable hydrogen storage capacity of well over 6 weight % coupled with extraordinary absorption kinetics such that the alloy powder absorbs 80% of its total capacity within 2 minutes at C.

  31. Hydrogen storage alloy electrode

    Matsushita Electric Industrial Co., Ltd. Inventor: Yamaguchi, Seiji; Yuasa, Shinichi; Ikoma, Munehisa. Patent Application Number: 263756. Date: 5 Mar 1999

    Patent Number US620732

    Disclosed is a hydrogen storage alloy electrode for use in alkaline storage batteries that can reduce internal resistance of the battery and can give an excellent output characteristic and a long cycle life to the battery. The electrode comprises an AB.sub.5 -type hydrogen storage alloy powder, a yttrium compound and a compound of a light rare earth element. The total content of the yttrium compound and the compound of a light rare earth element is in a range of 0.5 to 2.0 parts by weight per 100 parts by weight of hydrogen storage alloy powder. Preferable ratios of the yttrium compound and the compound of a light rare earth element selected from La, Ce, Pr and Nd are, respectively, 60 wt % or more and 7 wt % or less in the total amount of the yttrium compound and the compound of the light rare earth element.

  32. Magnesium Mechanical Alloys for Thermal Hydrogen Storage

    Energy Conversion Devices, Inc. Inventor: Sapru, Krishna; Ming, Lu; Stetson, Ned, T. Patent Application Number: EP99918756. Date: 21 Apr 1999

    Patent Number EP1082469

    A mechanically alloyed hydrogen storage material having 75-95 atomic percent Mg, 5-15 atomic percent Ni, 0.5-6 atomic percent Mo, and at least one additional element selected from the group consisting of Al, C, Ca, Ce, Co, Cr, Cu, Dy, Fe, La, Mn, Nd, Si, Ti, V, and Zr, preferably between 1-15 atomic %. The mechanically alloyed hydrogen storage preferably contains from 3-15 atomic % C and at least one other element selected from the group consisting of Al, Ca, Ce, Cu, Dy, Fe, La, Mn, and Nd. The hydrogen storage materials are created by mechanical alloying in a milling apparatus under an inert atmosphere, such as argon, or a mixed atmosphere, such as argon and hydrogen. The speed and length of the milling are varied.

  33. Hydrogen storage alloys and methods and improved nickel metal hydride electrodes and batteries using same

    Energy Conversion Devices, Inc. Inventor: Ovshinsky, Stanford R; Young, Rosa T; Chao, Benjamin. Patent Application Number: 064543. Date: 22 Apr 1998

    Patent Number US6210498

    Reversible hydrogen storage alloys and methods and electrodes formed therefrom for nickel metal hydride batteries, in which the alloys are quenched from a melt at cooling rates selected to provide a high degree of disorder with an optimum local environment.

  34. Modified Electrochemical Hydrogen Storage Alloy Having Increased Capacity, Rate Capability and Catalytic Activity

    Ovonic Battery Company, Inc. Inventor: Fetcenko, Michael, A; Young, Kwo; Ovshinsky, Stanford, R; Reichman, Benjamin; Koch, John; Mays, William. Patent Application Number: EP00923229. Date: 11 Apr 2000

    Patent Number EP1093528

    A modified Ti-V-Zr-Ni-Mn-Cr electrochemical hydrogen storage alloy which has at least one of the following characteristics: 1) an increased charge/discharge rate capability over that the base Ti-V-Zr-Ni-Mn-Cr electrochemical hydrogen storage alloy; 2) a formation cycling requirement which is reduced to one tenth that of the base Ti-V-Zr-Ni-Mn- Cr electrochemical hydrogen storage alloy; 3) no chemical/thermal activation of the modified alloy is required to attain full operating capacity as is required by the base Ti-V-Zr-Ni-Mn-Cr electrochemical hydrogen storage alloy: and 4) an oxide surface layer having a higher electrochemical hydrogen storage catalytic activity than the base Ti-V- Zr-Ni-Mn-Cr electrochemical hydrogen storage alloy.

  35. Mm-Ni type hydrogen storage alloy for Ni/MH secondary cell

    Korea Advanced Institute of Science and Technology. Inventor: Lee, Jai Young; Jang, Kuk Jin; Jung, Jae Han; Kim, Dong Myung; Yu, Ji Sang; Lee, Sang Min; Park, Jeong Gun; Lee, Ho. Patent Application Number: 080137. Date: 15 May 1998

    Patent Number US6106768

    There are disclosed Mm/Ni type hydrogen storage alloys for Ni/MH secondary cells. The alloys which allow the cells to be of high performance and high capacity can be prepared at lower costs than the production costs of conventional Co-rich hydrogen storage alloys, by reducing the amount of the Co element. The Co element is partially or wholly replaced by by Cr, Cu, Fe, Zn and/or Zi, which are each known to be of stronger affinity for hydrogen than is Co and to have such a strong oxidation tendency in electrolytes as to form a highly dense oxide. The novel alloys have discharge capacities and electrode life span as good as those of the conventional Co-rich hydrogen storage alloys but have advantages over the Co-rich alloys, including performance-to-cost.

  36. Hydrogen storage alloy composition and electrode using said alloy composition

    Shin-Etsu Chemical Co., Ltd. Inventor: Shinya, Naofumi; Sugahara, Hiroto. Patent Application Number: 961493. Date: 30 Oct 1997

    Patent Number US6106769

    A hydrogen absorbing alloy composition for a nickel-hydrogen secondary battery which includes LnNi.sub.5 hydrogen absorbing alloy, where Ln represents at least one rare-earth element. The hydrogen absorbing alloy composition also includes at least one compound selected from the group consisting of heavy rare-earth oxides, heavy rare-earth hydroxides, compound oxides including at least one rare-earth element and compound hydroxides including at least one rare-earth element. Rare- earth elements can be selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Exemplary hydrogen absorbing alloy compositions include La alone or in combination with one other rare-earth element, such as Ce, Pr, Nd, or Sm. Exemplary rare- earth oxides include Yb.sub.2 O.sub.3, Er.sub.2 O.sub.3 and GdO.sub.3 and exemplary rare-earth hydroxides include Yb(OH).sub.3 and Er(OH).sub. 3.

  37. Hydrogen Storage Alloy Electrode, Battery Including the Same and Method for Producing the Both

    Matsushita Electric Industrial Co., Ltd. Inventor: Moriwaki, Yoshio; Kuranaka, Sou; Iwasaki, Mizuo; Yamasaki, Yasuhiko; Maeda, Akihiro. Patent Application Number: JP0002343. Date: 10 Apr 2000

    Patent Number WO0062359

    A hydrogen storage alloy electrode comprising a hydrogen storage alloy (3) and a conductive metal (4) and completely free of organic binder is disclosed, wherein at least two layers of an active material holding layer and a conductive metal layer essentially are integrated into an electrode sheet having a conductive network communicating throughout the electrode. The electrode can be used in a nickel-metal hydride storage battery, for example, particularly exhibits high efficiency charge /discharge characteristics while satisfying general characteristics as a battery, and has a relatively low cost and facilitates recycling.

  38. Electrochemically Stabilized CaNi 5 Alloys and Electrodes

    Energy Conversion Devices, Inc. Inventor: Ovshinsky, Stanford, R; Young, Rosa, T. Patent Application Number: US0011223. Date: 27 Apr 2000

    Patent Number WO007069

    An electrochemically stabilized Ca-Ni hydrogen storage alloy material for use as the active negative electrode material of an alkaline electrochemical cell. The alloy material includes at least one modifier element which stabilizes the alloy material from degradation during electrochemical cycling in an alkaline cell, by protecting calcium within the alloy and preventing dissolution of calcium into the alkaline electrolyte. The alloy has the formula (Ca 1-x-y M x Ni 2y )Ni 5-z Q z , where M is at least one element selected from the group consisting of misch metal, rare earth metals, zirconium and mixtures of Zr with Ti or V, Q is at least one element selected from the group consisting of Si, Al, Ge, Sn, In, Cu, Zn, Co, and mixtures thereof, x ranges between about o.o2 and o.2, y ranges between about 0.02 and 0.4, and z ranges from about 0.05 to about 1.00.

  39. Metal hydride system eyed by GM for electric vehicles

    Wrigley, A

    American Metal Market (USA), vol. 108, no. 64, pp. 9, 4 Apr. 2000

    A metal hydride system for storing hydrogen gas as a solid in a fuel cell-powered car or truck has caught the attention of General Motors Corp as it continues its effort to develop very-high-mileage family vehicles. The solid-state hydrogen storage system, which contains magnesium alloy in powder form, is under development at Energy Conversion Devices Inc (ECD), Troy, Michigan, USA. In such batteries, Mg powder has the potential of reducing both the cost and weight of batteries for electric and hybrid-electric cars. As a storage media for hydrogen gas, it eliminates the need for sophisticated, costly tanks for holding hydrogen either in chilled liquid form or as a gas.

  40. New type of hydrogen absorbing alloys

    New Technology Japan (Japan), vol. 27, no. 4, pp. 16, July 1999

    Prof. Masuo Okada and his research team of the Graduate School of Engineering, Tohoku University, have developed a hydrogen absorbing alloy that features a H absorption volume that is more than double that of presently-used rare earth-based H-absorbing alloys. The newly developed H-absorbing alloy consists primarily of inexpensive chromium and titanium, also vanadium and other elements. The alloy's V content is low, from one-half to one-fourth, compared with conventional types of V-based H-absorbing alloys, so that the alloy manufacturing cost is low. Electric automobiles running on fuel cells require tanks of high H-absorbing capacities, so the new H-absorbing alloy is expected to move the electric automobile fuel battery, a big step forward toward commercialization. Contact: Tohoku University, Graduate School of Engineering, 02, Aoba, Aramaki, Aoba-ku, Sendai City, Miyagi Pref. 980-8579, Japan; tel +81-22-217-7334; fax +81-22-217-7374.

  41. Research consortium studies development of magnesium hydrogen-storage materials

    JOM (USA), vol. 50, no. 6, pp. 8, 66, June 1998

    US researchers from five organizations have joined forces to develop Mg-based alloys that could be used in rechargeable batteries for cellular phones, power tools, and cars. Participating in the $8.2 million project funded through the Advanced Technology Program of the National Institute of Standards and Technology are Ovonic Battery Company, Crucible Research, Oak Ridge National Laboratory, the Colorado School of Mines, and Ames Laboratory. Magnesium can store approx6.5% hydrogen by weight. Although Mg will not release hydrogen unless it is heated to 500-600 deg C, project participants hope to overcome that problem by modifying the Mg with other elements.

  42. Magnesium holds promise for new hydrogen-storing alloy

    Materials Performance (USA), vol. 37, no. 5, pp. 3, May 1998

    The US Department of Energy's Ames Laboratory is helping develop Mg-based alloys for rechargeable batteries that would be lighter, environmentally safer, and would store more energy than the lead-acid batteries used in cars and the nickel-cadmium batteries in power tools, cellular phones, and electronics. Pure Mg is desirable compared to other alloys that absorb and release hydrogen because it is lighter and stores approx6.5% H by weight, or 5% more than rare earths, Ni, zirconium, and titanium commonly used in Ni-metal-hydride batteries. However, Mg won't release H unless it is heated to 500-600 deg C, a problem project participants hope to overcome by modifying the metal with other elements.

  43. New nickel electrode material

    Japan Technology Highlights (USA), vol. 8, no. 10, pp. 3, 14 May 1997

    T. Sakai of the Metal Materials Laboratory of the Osaka Government Industrial Research Institute in Japan, in collaboration with Fukuda Metal Flakes Industry, has developed low-strain Ni flakes as an electrode material for nickel-hydrogen batteries. By shaping into flakes, the surface area of Ni was increased more than a factor of five, and internal stress was relieved to increase adhesiveness. Compared with foamed Ni, it is less expensive, and the capacity factor is improved 20-30%.

  44. Nickel-metal hydride battery with long service life

    New Technology Japan, vol. 24, no. 4, pp. 30, July 1996

    Sanyo Electric Co., Ltd (Tokyo, Japan) has developed a nickel-metal hydride battery available in three types that have longer service lives than a lithium ion battery of the same volume. A new type of material is used to fabricate the electrodes, by which the battery capacity has been increased considerably. The anode uses a cobalt compound with excellent electric conductivity, through which a new type of high-utility, large-capacity anode has been developed. The introduction of a new electrode manufacturing technique has led to the development of a new type of high-quality anode. In addition, a unique technique to treat the surface of the hydrogen occlusion alloy enables the catalytic performance to be improved, which led to the development of a new high-capacity cathode.