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Development of Ti Zr Mn Based Hydrogen Storage Alloys for a Soft Actuator

Development of Ti Zr Mn Based Hydrogen Storage Alloys for a Soft Actuator

The requirements for hydrogen storage alloys for the MH actuators are long cycle life, suitable equilibrium pressure for applications, small hysteresis, flat plateau, ease of initial activation, and cost. The volumetric density and weight density of hydrogen in these alloys are not a significant issue for the MH actuators, because they require so little hydride material for their operation. Figure 2 shows a schematic image of pressure-composition (P-C) isotherms at two

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Crystal Structures of La  Mg  Nix (x=3  4) System Hydrogen Storage Alloys

Crystal Structures of La Mg Nix (x=3 4) System Hydrogen Storage Alloys

Both La–Ni and Mg–Ni system alloys are representative hydrogen storage alloys. The La–Mg–Ni system, which is a hybrid of these two, has recently been attracting attention as a negative electrode material for Ni–MH secondary batteries, owing to its potential advantages, which include longer life, higher capacity, and environmental conformity. Kohno et al. 1) reported that La

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Structure and Electrochemical Properties of La4MgNi17.5M1.5 (M=Co,Fe,Mn) Hydrogen Storage Alloys

Structure and Electrochemical Properties of La4MgNi17.5M1.5 (M=Co,Fe,Mn) Hydrogen Storage Alloys

phase (lower plateau pressure), respectively[29]. It also can be found that the plateau pressure of the substituted alloys are in the order: Co>Fe>Mn, which correspond to the study reported by Huang[30] et al that the increase of cell volume could decrease the pressure of hydrogen absorption. The hydrogen storage capacity of alloy electrodes also matches well with the discharge capacity of them.

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Microstructures and Electrochemical Properties of LaNi3.55Co0.2-xMn0.35Al0.15Cu0.75(V0.81Fe0.19)x Hydrogen Storage Alloys

Microstructures and Electrochemical Properties of LaNi3.55Co0.2-xMn0.35Al0.15Cu0.75(V0.81Fe0.19)x Hydrogen Storage Alloys

capacity decay of the hydrogen storage alloy electrode is mainly due to the pulverization and oxidation [28,29]. As mentioned above, the rich-Ni secondary phase increases the amount of phase boundary, which releases the stress formed in the process of hydrogen absorbing and then improves cycling stability. Moreover, Lin et al. [30] reported the increase of cell volume unit decreased the volume dilatation in the process of hydride formation, and therefore contributes to the charge-discharge life cycles. Unfortunately, it is well-known that Fe in the KOH solution more easily oxidized than Ni due to the lower surface energy of Fe. The increase in Fe and the decrease of Ni not only cause the deterioration of the corrosion resistance with increasing x value and then increase the loss of the alloy, but also degrade the electrochemical kinetics at the surface. Furthermore, it is reported that the V- dissolution caused shortening of cycle life [31].The increase in V with increasing x value is unfavorable for the cycling stability of the alloy electrodes. Consequently, the disadvantageous factor is prominent for the degradation of the cycling stability of LaNi 3.55 Co 0.2-x Mn 0.35 Al 0.15 Cu 0.75 (V 0.81 Fe 0.19 ) x

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Improved Electrochemical Properties of Cu-dopped LaNi4.1-xCo0.6Mn0.3Cux (x= 0-0.45) Hydrogen Storage Alloys at 238 K

Improved Electrochemical Properties of Cu-dopped LaNi4.1-xCo0.6Mn0.3Cux (x= 0-0.45) Hydrogen Storage Alloys at 238 K

capacity at 60 mA/g at 303K, is presented in Table 2. After 30 cycles at 303K, the cycling stability varies from 83.4% (x=0) to 78.5% (x=0.15), then to 83.7% (x=0.45), accordingly it is confirmed that the low-Cu alloys (x=0.15) exhibit high pulverization rate as predicted above. In order to verify the pulverization difference, the scanning electron microscopy (SEM) observation of the electrodes after 30 th cycles is presented in fig.4. All the bigger particles pulverize to similar average sizes about 2-10 μm. However, many micro-cracks produced in the big particles during the charge/discharge cycle in x=0.15 as shown in fig.4(b), which is more obvious than that of x=0 as shown in fig. 4(a). Thus the alloy x=0.15 exhibits high cycling pulverization rate. As mentioned above, the increase in Cu content lowers the c/a ratios which enlarging the cycling pulverization rate. On the other hand, the increase in Cu content reduces the micro-hardness of the alloys, which improving the pulverization resistance. Therefore, it is reasonable to assume that, the increase in pulverization rate of alloy electrodes with x from 0 to 0.15 is mainly attributed to the former. However, when x exceeds 0.15, the later will become dominant and decrease the pulverization rate. Although all the alloys exhibit a poor cycling stability at 303 K, the degradation of LaNi 4.1−x Co 0.6 Mn 0.3 Cu x are no more than 0.1% per cycle at 238K, which

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Phase Structure and Electrochemical Properties of La0.7Ce0.3Ni3.83-xMn0.43Co0.25Al0.26Cu0.48(Fe0.43B0.57)x Hydrogen Storage Alloys

Phase Structure and Electrochemical Properties of La0.7Ce0.3Ni3.83-xMn0.43Co0.25Al0.26Cu0.48(Fe0.43B0.57)x Hydrogen Storage Alloys

boundary, which releases the stress formed in the process of hydrogen absorbing and then improves anti-pulverization of the alloy electrodes. However, iron corrodes more easily in the alkaline electrolyte compared with cobalt due to the lower surface energy. The increase of Fe content and decrease of Ni content will degrade the corrosion resistance of alloy electrode, and then deteriorate the cycling stability of alloy electrode. Obviously the disadvantageous factors is prominent for cycling stability of La 0.7 Ce 0.3 Ni 3.83-x Mn 0.43 Co 0.25 Al 0.26 Cu 0.48 (Fe 0.43 B 0.57 ) x alloy electrodes.

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Effect of Surface Coating on Electrochemical Properties of Rare Earth-Based AB5-type Hydrogen Storage Alloys

Effect of Surface Coating on Electrochemical Properties of Rare Earth-Based AB5-type Hydrogen Storage Alloys

combination of fluorination and palladium deposition, and discovered a excellent hydrogen storage property. Besides combined treatment, single fluorination was reported to be an effective method [19, 20]. Microencapsulation of alloy powders with metallic or alloy coatings such as Ni–P, Pd, Cu, Co were reported to improving the catalytic activity and high-rate dischargeability owing to the effect of transition metal on hydrogen reaction catalysis [21-23]. Polymer coating was also recently reported to improve the electrochemical properties owing to functional groups which help in hydrogen transferring [24].

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Analysis of Inhomogeneities in Hydrogen Storage Alloys: A Comparison of Different Methods

Analysis of Inhomogeneities in Hydrogen Storage Alloys: A Comparison of Different Methods

In this work we have realized a simplified model to analyze compositional inhomogeneities in commercial hydrogen storage alloys. We have used it to evaluate the effect of the thermal annealing, together with calorimetric, PCIs and XRD measurement. We have compared results with composition distribution histograms based on Rietveld refinement of XRD patterns. Finally we studied the variation of α and β phases crystallographic parameters with H2 pressure. Keywords: Hydrogen Storage; Alloys; Inhomogeneities; Sloping Plateau

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The Effect of Melt spun Treatment on the Properties of La4MgNi17Co2 Hydrogen Storage Alloys

The Effect of Melt spun Treatment on the Properties of La4MgNi17Co2 Hydrogen Storage Alloys

rate discharge-ability of MH electrode, i.e., the electrochemical reaction rate on the alloy surface and the diffusion rate of hydrogen in the bulk of the alloy [32]. To investigate the factors of discharge kinetics in alloy electrodes, linear polarization and potential-step experiments were carried out on the alloy electrodes respectively, and the results are presented in Fig.4 and Fig.5. According to the obtained curves, the exchange current density (J 0 ) and hydrogen diffusion coefficient (D) were calculated and

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Structures and Hydrogen Storage Properties of Mg45M5Co50 (M=Zr, Ni, Al) Ternary Alloys by Mechanical Alloying

Structures and Hydrogen Storage Properties of Mg45M5Co50 (M=Zr, Ni, Al) Ternary Alloys by Mechanical Alloying

diffraction (XRD) revealed that the Bragg peaks of these alloys were broadened, which indicated that the crystalline size of these alloys was fully pulverized. Both BCC phase and amorphous phase in the ternary alloys were found after ball milling for more than 80 h by transmission electron micrograph (TEM). With the increase of ball milling time, however, the BCC phase disappears gradually and the amorphous phase dominated the alloys eventually. Pressure-Composition-Isotherms (P-C-T) measurements showed that these ternary alloys containing BCC phase can absorb hydrogen at 353 K within the hydrogen pressure range of 0 ~ 3 MPa. Mg 45 Al 5 Co 50 alloy had the maximum hydrogen

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Saturation dynamics of aluminum alloys 
		with hydrogen

Saturation dynamics of aluminum alloys with hydrogen

UC RUSAL is one of the largest companies in the global aluminum industry. It accounts for almost 9% of the world's primary aluminum output and is expected to boost its proportion of alloys up to 80%. One of RUSAL's promising development trends is the manufacture of bulk (flat-shaped) low-alloyed aluminum alloy ingots. A number of technical and technological solutions aimed toward improving the existing technology and ensuring a decrease in hydrogen content in aluminum melt up to a level of less than 0.1 cm 3 /100 g have been developed in

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Hydrogen Assisted Degradation of Titanium Based Alloys

Hydrogen Assisted Degradation of Titanium Based Alloys

The titanium alloys whose microstructures contain mostly the phase, when exposed to an external hydrogen environ- ment at around room temperature, will degrade primarily through the repeated formation and rupture of the brittle hydride phase at, or very near, the gas-metal interface. 9) When only the phase is present, degradation is insensitive to external hydrogen pressure, since hydride formation in the phase can occur at virtually any reasonable hydrogen partial pressure. High voltage electron microscope inves- tigations of the hcp Ti-4%Al alloy 44) (Fig. 5), revealed that

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Ultrafine hydrogen storage powders

Ultrafine hydrogen storage powders

atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

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Phase Structure and Electrochemical Hydrogen Storage Characteristics of La0.7Ce0.3Ni3.85Mn0.8Cu0.4Fe0.15-x(Fe0.43B0.57)x (x = 0-0.15) Alloys

Phase Structure and Electrochemical Hydrogen Storage Characteristics of La0.7Ce0.3Ni3.85Mn0.8Cu0.4Fe0.15-x(Fe0.43B0.57)x (x = 0-0.15) Alloys

Secondly, it is also claimed that the stability of metal hydride gradually decreases with increasing B content [10]. The increase of B content will lower the stability of the alloy hydride and then cause the hydrogen desorption easily, which contributed to hydrogen diffusion. Thirdly, Iwakura et al. [21] have reported that the oxidation of Fe on the alloy surface limited the hydrogen transfer from the surface to the bulk of the alloys. As mentioned above, the decrease of Fe content causes the decrease of surface oxide film, which is beneficial to the hydrogen diffusion.

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Wind to Hydrogen for Energy Storage

Wind to Hydrogen for Energy Storage

Now we have the wind's energy delivered in a useful form to the electrolyzer. An electrolyzer has one main goal, to take in water and electricity and produce hydrogen and oxygen. Here we use Proton Energy Systems HOGEN 40RE proton exchange membrane as electrolyzers. Hydrogen H-Series generators utilize Proton Exchange Membrane (PEM) cell stack and Pressure Swing Adsorption (PSA) technology to produce ultra-high purity hydrogen for various applications, some of which include materials processing, generator cooling and semiconductor fabrication, etc. These systems benefit hydrogen users by improving supply reliability and site safety, while also reduces hydrogen storage space. The generators are modular, field-upgradeable and designed to compete with delivered hydrogen anywhere in the world. A single H 6 unit will supply the equivalent of one and one-half jumbo tube trailers every

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Hydrogen Permeation of Ni Nb Zr Metallic Glasses in a Supercooled Liquid State

Hydrogen Permeation of Ni Nb Zr Metallic Glasses in a Supercooled Liquid State

important to develop a new membrane alloy with high hydrogen diffusivity and medium hydrogen solubility in order to suppress the severe hydrogen embrittlement. Unfortunately, it is impossible to use the metallic glass as a membrane in the supercooled liquid state due to the crystallization. Nowadays, the Nb and V metals having the bcc structure in which hydrogen can diffuse relatively faster than in the fcc structure, have been adopted as the base metal of the new membrane alloys. As a new alloy design, we can suggest that other bcc metals showing high hydrogen diffusivity and low hydrogen solubility such as Fe should be focused for a base metal and that the medium hydrogen solubility should be given to such bcc metals by alloying with elements having high hydrogen affinity, resulting that the developed alloys might show the high hydrogen permeability with high hydrogen diffusivity and medium solubility. This is one of the potential suggestions derived from this work. In this study, we demonstrated a possibility that the hydrogen permeation can increase significantly with increasing diffusivity and with decreasing solubility through the insight of hydrogen permeation in the supercooled liquid of the metallic glasses. We suggest that it is important to develop a new membrane alloy with high hydrogen diffusivity.

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Ultrafine hydrogen storage powders

Ultrafine hydrogen storage powders

atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

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(La1.66Mg0.34)Ni7-based alloys : Structural and Hydrogen Storage Properties

(La1.66Mg0.34)Ni7-based alloys : Structural and Hydrogen Storage Properties

compounds [12-25]. High hydrogen capacity, moderate hydrogen equilibrium pressure as well as light and less expensive elements makes them remarkable from an economical point of view. On the other hand, unknown structural properties raise the need for basic, crystallographic research. Recently, details about the structures of Ce 2 Ni 7 H 4/4.7 [26, 27], Ce 2 MgCo 9 H 12 [28], La 2 Ni 7 H 6.5 [29], La 2 Ni 7 H x (x =

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Gaseous and Electrochemical Hydrogen Storage Properties of Nanocrystalline Mg2Ni Type Alloys Prepared by Melt Spinning

Gaseous and Electrochemical Hydrogen Storage Properties of Nanocrystalline Mg2Ni Type Alloys Prepared by Melt Spinning

technique. The structures of the as-cast and spun alloys have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM). The electrochemical per- formances were evaluated by an automatic galvanostatic system. The hydrogen absorption and desorption kinetics of the alloys were determined by using an automatically controlled Sieverts apparatus. The results indicate that the sub- stitution of Cu for Ni does not alter the major phase Mg 2 Ni. The Cu substitution significantly ameliorates the electro-

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La-Ni based Alloys Preparation for Hydrogen Reversible Sorption and their Application for Renewable Energy Storage

La-Ni based Alloys Preparation for Hydrogen Reversible Sorption and their Application for Renewable Energy Storage

One of the best metal for hydrogen storage is palladium (Pd) and its alloys, but the price of this material does not allow its use widely [9,10]. Complex hydrides have a biggest storage hydrogen density in comparison with other types of hydrides, but most of them are not relevant for reversible hydrogen sorption. The micro-porous adsorbents and interstitial hydrides have similar hydrogen capacity, but intermetallic hydrides can operate at ambient temperatures. The aim of hydrogen storage technologies is to reduce the volume that hydrogen naturally occupies in its thermodynamically stable state under ambient conditions. Different ways of hydrogen storage are shown in Figure 1.

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