Hydrogen Storage Alloy Powders Research Articles

Preparation of Mg2Ni Hydrogen Storage Alloy Materials by High Energy Ball Milling

In this paper, Mg2Ni hydrogen storage alloy powder was prepared by high-energy ball milling mechanical alloying method, and the influence of stirring shaft rotation speed, ball milling time, and different sizes of ball mills on the formation time, powder morphology, and crystal structure of Mg2Ni alloy during ball milling was studied. The results show that the Mg2Ni alloy was obtained by high-energy ball milling in this work, and the efficiency was increased by about 76% compared with the traditional ball milling method. In the case of higher rotational speed or larger blades, the time to generate Mg2Ni alloy can be advanced, the alloying process can be shortened, and Mg2Ni alloy with a particle size of less than 10 um can be obtained. However, after the ball milling reaches a certain time, the cold welding and crushing of the alloy powder reach a balance, and the particle size is basically unchanged. The hydrogen storage alloy was activated, the hydrogen storage PCT curve was detected, and the hydrogen absorption kinetic curve and the PCT curve were analyzed. After ball milling at 900/1100 rpm for 13 hours, a Mg2Ni alloy with a single composition, extremely low impurity content, and partially amorphous and nanocrystalline coexistence was obtained. Its mass hydrogen storage density also reached the theoretical value of 3.6 wt%.

Role of atomic hydrogen supply on the onset of CO2 methanation over La–Ni based hydrogen storage alloys studied by in-situ approach

Mechanochemical CO2 methanation reactions using LaNi5 and LaNi4.6Al0.4 hydrogen storage alloy powders were investigated by the in-situ monitoring of the gas pressure change during ball-milling. Methane generation begins when the H2 partial pressure drops due to the H-uptake by the powder. Phase transition occurred in the sample after milling for 15 min and 224 min, with separate metallic Ni, La-oxide and La-hydroxide phases observed. Methane generation continued even after this phase separation. Our results imply that the formation of La-hydroxide at the surface and sub-surface contributed to methane generation during ball-milling. A comparison of LaNi5 and LaNi4.6Al0.4 suggests the amount of hydrogen stored in the hydrogen storage powder dominates the timing of the onset of the methane generation.

Selective Formation of Ce-Ni Hydrogen Storage Alloys By Electrodeposition in LiCl-KCl-CeCl3 Melts Using Ni As Cathode

Cerium-nickel based hydrogen storage alloys are one of the important new rare earth-based hydrogen storage alloys due to their high discharge capacities, easy activation and good hydrogen pressure. Cerium-nickel based alloy compound, CeNi5, is usually used as the hydrogen storage alloy in Ni/MH battery, due to their favorable electrochemical activation, improved discharge and charge kinetic properties. CeNi2 and CeNi3, are also used as hydrogen storage alloys. The electrochemical way in molten salts is more economic for the metallurgical industry, because it has simpler in operation and lower in energy consumption than many existing industrial technologies. However, the electrochemical formation of Ce-Ni hydrogen storage alloys by selective electrodeposition has not been reported on a Ni cathode in LiCl-KCl molten salts. In this study, the electrochemical behavior of Ce(III) ions was explored in molten LiCl-KCl salts using nickel as working electrode to produce the Ce-Ni hydrogen storage alloys. Cyclic voltammetric and square wave voltammetric results indicated that the electrochemical reduction of Ce (III) appeared at a less negative value than that recorded on a W electrode because of the formation of Ce-Ni alloy compounds by the electro-deposition of Ce on a Ni electrode. The nucleation mechanism of Ce deposited on a Ni electrode based on the Scharifker-Hill non-dimensional theoretical model was found to be the progressive nucleation. The change of electrode surface morphology with the deposited time was observed by SEM, which clearly indicated that the nucleation and growth of Ce follows the mechanisms of dendritic growth. Based on the studies of the above electrochemical behavior, Ce-Ni alloys were prepared using potentiostatic electrolysis, five kinds of Ce-Ni intermetallic compounds, CeNi5, Ce2Ni7, CeNi3, CeNi2 and CeNi were formed under our experiment conditions in LiCl-KCl-CeCl3 melts. XRD and SEM-EDS analysis results showed that the hydrogen storage alloys of CeNi5, CeNi3 and CeNi2 could be selectively prepared using potentiostatic electrolysis by controlling applied potential. Furthermore, The thermodynamic properties of Ce-Ni compounds, such as Gibbs free energy(ΔG), enthalpy(ΔH) and entropy(ΔS) of formation for each Ce-Ni alloy compound as well as activity and partial molar Gibbs energy of Ce in Ce-Ni alloy were computed employing open circuit chronopotentiometry measurement. Therefore, this work presents a promising method for the preparation of the Cerium-nickel based hydrogen storage alloys. Keywords: Electrochemical behaviour; Electrochemical formation; Ce-Ni intermetallic compounds; Thermodynamic properties References [1] Y. Zhang, H.Y. Yin, S.D. Zhang, D.Y. Tang, Z.W. Yuan, T.H.Yan, W.F. Zheng, D.H. Wang,Preparation of CeNi2 intermetallic compound by direct electroreduction of solid CeO2-2NiO in molten LiCl,J. Rare Earth.3(9)(2012) 923-927.[2] B.J. Zhao, L. Wang, L. Dai, G.H. Cui, H.Z. Zhou, R.V. Kumar, Direct electrolytic preparation of cerium/nickel hydrogen storage alloy powder in molten salt,J. Alloys Compd. 468 (2009) 379-385.[3] B.J. Zhao, X.G. Lu, Q.D.Zhong, C.H. Li, S.L. Chen, Direct electrochemical preparation of CeNi5 and LaxCe1-xNi5 alloys from mixed oxides by SOM process,Electrochim. Acta 55 (2010) 2996-3001.Fig.1 Square wave voltammogram for Ni electrode in LiCl-KCl-CeCl3 melts at 873 K. Pulse height: 0.1 V; potential step: 0.002 V; frequency: 20 Hz. Figure 1

Electrolytic Reduction of Cerium Oxide

Since the early 2000s, when the Fray-Farthing-Chen (FFC, direct reduction) and the Ono-Suzuki (OS, indirect reduction) processes on titanium oxide were elucidated, several additional metal oxides (Zr, Ta, Cr, and Nb) have been reported to electrolytically reduce to their metallic state in molten CaCl2-CaO.1-3 However, the electrolytic reduction of cerium oxide has resulted in mixed degrees of success. As such, the goal of this study is to identify side reactions that occur that are parasitic to the overall reaction of producing cerium metal and correlate that to the composition of the salt. Previous reports indicate that the reaction pathway from CeO2 to Ce0 is not direct and includes side reactions that result in the formation of Ce2O3, CeOCl and CeCl3.3-5 Our efforts to use cyclic voltammetry to identify side reactions, which allowed for the determination of approximate concentrations of side reaction products as well as Ce0 produced as a result of electrolysis, will be presented. Acknowledgements For financial support of this work, we acknowledge the U.S. Department of Energy through the LANL LDRD Program (Mission Foundations Research Project #20170558ER). References 1 Chen, G. Z., Fray, D. J. & Farthing, T. W. Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride. Nature 407, 361-364 (2000). 2 Suzuki, R. O., Ono, K. & Teranuma, K. Calciothermic reduction of titanium oxide and in-situ electrolysis in molten CaCl2. Metallurgical and Materials Transactions B 34, 287-295, (2003). 3 Claux, B., Serp, J. & Fouletier, J. Electrochemical reduction of cerium oxide into metal. Electrochimica Acta 56, 2771-2780, (2011). 4 Zhao, B. et al. Direct electrolytic preparation of cerium/nickel hydrogen storage alloy powder in molten salt. Journal of Alloys and Compounds 468, 379-385, (2009). 5 Castrillejo, Y., Bermejo, M. R., Pardo, R. & Martı́nez, A. M. Use of electrochemical techniques for the study of solubilization processes of cerium–oxide compounds and recovery of the metal from molten chlorides. Journal of Electroanalytical Chemistry 522, 124-140, (2002).

Microstructure and improved hydrogen storage properties of Mg based alloy powders prepared by modified milling method

In this study, the modified preparation method of combining planetary and vibratory ball milling was proposed to prepare Mg based hydrogen storage alloy powders. The comparison of micromorphology and hydrogen storage behaviour between Mg2Ni prepared using the modified and conventional preparation methods were investigated experimentally. The comparison results showed that the combination of first planetary and then vibratory ball milling has more favourable effect on improving both the kinetics and the thermodynamics of ball milled Mg2Ni alloys. The sample synthesised by first planetary milling for 40 h and then vibratory milling for 30 h has faster hydrogen absorption kinetics and lower dehydriding onset temperature than those prepared by the single method of planetary or vibratory milling and hydriding combustion synthesis owing to its popcorn-like microstructure. Moreover, this kind of modified method reduces the reaction enthalpy and activation energy by up to ∼18 and 22% respectively.

Influence of Active Hydrogen Discharged from Palladium-Nickel Alloy Powder on Biological Cells

A selective cancer cell death induced by discharged hydrogen from Pd-Ni base hydrogen storage alloy (HSA) powder is demonstrated. From the cell experiment and the measurement of surviving cell rate, it was found that cell death was seen only in cancer cells (HeLa : cervical cancer cell) after 24h- and 48h-immersion of Pd-5at.%Ni alloy powder, while no harmful influence was observed in normal cells (MDCK : renal epithelial cell). The range of cancer cell death was limited just near the HSA powder. It is suggested that the hydrogen radical emitted from the HSA powder induces the formation of hydrogen peroxide and brings a detrimental effect in the cancer cell, while hydrogen peroxide is decomposed by the enzyme, catalase, in normal cells, resulting in the selective death of cancer cells.

Effects of pretreatment on MlNi4.00Co0.45Mn0.38Al0.3 hydrogen storage alloy powders and the performance of 6 Ah prismatic traction battery

This paper investigates the effects of pretreatment of the MlNi4.00Co0.45Mn0.38Al0.3 (Ml: Lanthanum rich misch metal) alloy powders in 12 M NaOH solutions with 0.05 M NaBH4 at 110 °C for 3 h and the performance of 6 Ah prismatic traction battery. The alloy powders are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy with energy dispersive X-ray detector, inductively coupled plasma-atomic emission spectroscopy, laser particle size analyzer and BET chemisorptions analyzer. The electrochemical performance of the battery was effectively improved by the pretreatment of alloy powders with a NaOH/NaBH4 solution. It is found that the discharge efficiencies at 30C at room temperature and at 3C at −20 °C are increased from 5.6% to 88.1% and from 3.7% to 83.7%, respectively. The cycle lifetime at 3C of SOC of 80% is increased from 2200 to 4424. The enhanced performance is attributable to the change of the surface structure and properties of alloy powders by pretreatment.

Electrochemical performance of polyaniline electroless deposited La–Mg–Ni-based hydrogen storage alloys

Polyaniline (PANI) electroless-deposition is applied onto La–Mg–Ni-based La0.80Mg0.20Ni2.70Mn0.10Co0.55Al0.10 hydrogen storage alloy powders in order to improve electrochemical and kinetic properties. FE-SEM and FT-IR results reveal that coral-like PANI particles are deposited on the surface of the alloy. Owing to the PANI coating the initial discharge capacity of the alloy electrodes increases from original 174mAhg−1 to 226mAhg−1, the capacity retention rate at 200 cycles (S200) increases from 85% to 88%, and the high rate discharge ability (HRD) is scaled up by 18% at discharge current density of 1500mAg−1. Linear polarization, EIS, anodic polarization and potential static step discharge measurements indicate that charge transfer resistance decreases and the hydrogen diffusion rate increases after PANI-coating.

Estimating the size distribution of anode and cathode activating agents in the crushed products of nickel metal hydride batteries from hybrid vehicles and its classification

Nickel metal hydride batteries of hybrid vehicles contain Co and rare earth elements in the anode and cathode activating agents as well as in the main electrode component, Ni. The cathode electrodes comprise a porous Ni plate (cathode substrate) with nickel hydroxide as the cathode activating agent and the anode electrodes consist of a hydrogen storage alloy powder as the anode activating agent on a metal mesh substrate. A direct smelting method has been used to recover Ni from waste batteries, but the Co and rare earth elements are difficult to extract by this conventional method. To recycle Co and rare earth elements, physical pretreatment is necessary to separate the anode and cathode compounds before smelting. This study investigated the separation of anode and cathode activating agents in the < 0.075 mm fraction of crushed nickel metal hydride batteries using a cyclone and the anode activating agent was concentrated in the underflow product. After crushing the waste batteries a mixture of cathode and anode activating agents is recovered as fines, and a simple and fast size distribution measurement method for each activating agent is desirable to evaluate the physical separation results and improve the separation efficiency. The results show that further size classification of the < 0.075 mm fraction is effective to concentrate the anode activating agent for cylindrical type batteries.

337 水素吸蔵合金粉末分散ポリウレタン複合運動機能材料の電力制御による可逆運動(知的材料・構造システムおよび複合機能化材料・デバイス(4),ものづくりにおける基礎研究と先端技術の融合)

337 水素吸蔵合金粉末分散ポリウレタン複合運動機能材料の電力制御による可逆運動(知的材料・構造システムおよび複合機能化材料・デバイス(4),ものづくりにおける基礎研究と先端技術の融合)

Giant Bending Strain of Reversible Motion of Uni-Morph Soft Mover Composites Driven by Hydrogen Storage Alloy Powders Dispersed in Polyurethane Sheet

In order to generate the bending motion operated by pressure change in hydrogen gas, soft uni-morph composites were prepared, in which composites dispersed with not only driving particles of LaNi5 hydrogen storage alloy with Pd-Al2O3 catalyst powders to get high responsiveness, were piled up on a simple polyurethane sheet. Since the highest values of irreversible bending strain at the first hydrogenation ( 1 ) under 0.3 MPa H2 gas and the maximum irreversible bending strain during hydrogenation cycles ( m ) were remarkably obtained at the 35 vol% of LaNi5 powders dispersed in polyurethane composites, the bending strain of reversible motion was detected from the first to the 8th hydrogenation (r 1 and r 8 ) under 0.2 MPa H2 gas. The bending strain of reversible motion of polyurethane composites sheet is more than 2000 ppm, which was approximately equal to that of silicone rubber composites and is extremely larger than that (300 ppm) of ABS resin composites. Responsiveness (d=dt) of cyclic motion of elastic deformed mover composites, which were constructed with 35 vol%LaNi5 dispersed powder and matrix of polyurethane or silicone rubber, were more than 10 times higher than that of ABS composite. [doi:10.2320/matertrans.M2009178]

Preparation and Electrochemical Performances of Nickel Metal Hydride Batteries with High Specific Volume Capacity

Cylindrical nickel metal hydride (Ni-MH) battery with high specific volume capacity was prepared by using the oxyhydroxide Ni(OH) 2 and AB 5 type hydrogen storage alloy and adjusting the designing parameters of positive and negative electrodes. The oxyhydroxide Ni(OH) 2 was synthesized by oxidizing spherical β-Ni(OH) 2 with chemical method. The X-ray diffraction (XRD) patterns and the Fourier transform infrared (FT-IR) spectra indicated that β-NiOOH was formed on the oxyhydroxide Ni(OH) 2 powders, and some H 2O molecules were inserted into their crystal lattice spacing. The battery capacity could not be improved when the oxyhydroxide Ni(OH) 2 sample was directly used as the positive active materials. However, based on the conductance and residual capacity of the oxyhydroxide Ni(OH) 2 powders, AA size Ni-MH battery with 2560 mA·h capacity and 407 W·h·L −1 specific volume energy at 0.2C was obtained by using the commercial spherical β-Ni(OH) 2 and AB 5-type hydrogen-storage alloy powders as the active materials when 10% mass amount of the oxyhydroxide Ni(OH) 2 with 2.50 valence was added to the positive active materials and subsequently the battery designing parameters were adjusted as well. The as-prepared battery showed 70% initial capacity after 80 cycles at 0.5C. The possibility for adjusting the capacity ratio of positive and negative electrodes from 1 : 1.35 to 1 : 1.22 was demonstrated preliminarily. It is considered the as-prepared battery can meet the requirement of some special portable electrical instruments.

Direct electrolytic preparation of cerium/nickel hydrogen storage alloy powder in molten salt

The preparation of CeNi5 by direct electrochemical reduction of mixed powders of cerium oxide (CeO2) and nickel oxide (NiO) (atomic Ce/Ni ratio, 1:5) in a molten mixture of CaCl2 and NaCl (mass CaCl2/NaCl ratio, 7:3) at 820 °C has been studied. The influence of process parameters, such as sintering temperature, cell voltage, and temperature of the molten salt, on the electrolysis process are reported. The current–time plots are shown at constant voltage electrolysis under different conditions. The composition and morphology of the products were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results show that pure CeNi5 can be prepared by direct electrochemical reduction of mixed CeO2/NiO pellets sintered at 850–1250 °C in CaCl2/NaCl melt at a voltage of 2.5 V or higher for 11 h. The product from the electrolysis was in the form of porous pellets and could be readily ground into CeNi5 alloy powder. At a voltage of 2.5 V or higher, the reduction of the mixed oxide starts from NiO to Ni, followed by that of CeO2 on the surface of the newly formed Ni to form CeNi5 alloy. The reduction rate increases with increasing cell voltage and temperature of molten salt.

Application of Open Celled Al in the Alloy Hydride System for Hydrogen Storage

The open cell Al (or Al foam) was employed in the alloy hydride system due to the rapid heat conductivity of Al. The hydrogen storage alloy powders were packed in this storage system made of Al open cell, and the changes of temperature and equilibrium pressure of hydrogen desorbed were measured. By applying the open cell Al in this hydrogen storage system, the reaction sensitivity of the temperature and equilibrium pressure was far rapidly increased than that without the open cell Al.

Improvement of Bending Motion by Catalyst Addition of Pd-Al&lt;SUB&gt;2&lt;/SUB&gt;O&lt;SUB&gt;3&lt;/SUB&gt; Powder for an Uni-Morph Soft Device Constructed of Polymer Sheets with and without Powder Dispersion of Hydrogen Storage Alloy

In order to generate the soft bending motion driven by pressure change in hydrogen gas, a soft device was made up and tested. In former research, a unimorph structure was proposed, in which a silicone rubber with LaNi 5 alloy powder distributed was piled up on a pure silicone rubber sheet. Using this structure we succeeded a bending motion of the soft device by applying hydrogen gas pressure. However the mechanical response was slow. To improve the active motion, a catalyst of Pd-Al 2 Ο 3 powder was mixed into the hydrogen storage alloy powder in the rubber. By simple addition of catalyst powder before dispersion into the rubber, we obtained drastically modified responses and displacement in the movement of the device. The catalyst probably accelerated dissociation of hydrogen molecule on the surface of hydrogen storage material particle.

Giant Bending Motion of a Soft Actuator Controlled by Hydrogen Gas Pressure

A soft actuator with a giant bending motion controlled by hydrogen pressure for artificial muscles has been innovated. It resembles a bimetal and is constructed with soft silicone rubber sheets for driving and supporting. The LaNi5 hydrogen storage alloy powder is dispersed in the driving sheet. The reversible motion is observed and operated by hydrogenation and degassing. The giant bending motion of over 4000 ppm of strain was observed from 2 min to 3 h of hydrogenation time. The actuator developed shows a giant bending motion as large as that of a typical shape memory alloy.

Effect of Rare-Earth Elements on the Temperature Performances of Power Nickel-Metal Hydride Batteries for Electric Tools

Combined with the preparation of sub-C size power nickel metal-hydride (Ni-MH) batteries for electric tools, the influence of rare-earth elements on the charge-discharge performances of Ni-MH batteries at the high-rate and temperature extremes (65 and ) was especially investigated. With a mixture of 3% additives adding to the active slurry of positive electrode, a increase of oxygen-generated overvoltage was formed at the end of the charging process and the charge efficiency of batteries was improved from 34 to 69% at . In addition, it was shown that the particle size, composition, and microstructure of hydrogen storage alloy powders in the negative electrode are closely related with the discharge performances of battery at high rate and low temperature. A mixture of three -type hydrogen-storage alloy powders with different particle size and composition of La, Ce, and Co was used as the active materials in the negative electrodes. The discharge capacity and voltage of prototype sub-C Ni-MH batteries thus prepared approached and at and , and their cycle lifetimes at the alternative discharging mode and were over 280 and , respectively. Sub-C Ni-MH batteries prepared in the state-of-the-art meet the requirements of electric tools.

水素吸蔵合金粉末分散ポリマー運動素子の触媒処理による応答速度の向上

水素吸蔵合金粉末分散ポリマー運動素子の触媒処理による応答速度の向上

Effects of N2 mixed gas atomization on electrochemical properties of Mm(Ni,Co,Mn,Al)5.0 alloy powder

N 2 gas, N 2 –Ar mixed gas and Ar gas atomization followed by acid surface treatment was applied to improve electrochemical properties of AB 5 type hydrogen storage alloy powder. The shape of Ar atomized powder was spherical and it changed to be irregular with increasing N 2 content of mixed gas. Irrespective of gas kinds, electrodes of atomized powder showed the same discharge capacity as cast-pulverized powder under auxiliary electrical conductivity by nickel powder addition. Without nickel powder, however, N 2 atomized powder showed the best electrochemical properties as well as gas activation behavior. By the combination process of N 2 gas atomization and acid surface treatment, it was considered that irregular shape of N 2 atomized powder promoted electrical conductivity of electrodes and catalytic nickel concentrated surface layer was formed to increase the hydrogen storage rapidity.

Application of hydrogen-storage alloy electrode in electrochemical reduction of glucose

Abstract Electrolysis of glucose was performed at constant potential using hydrogen-storage alloy as catalytic reduction electrode. A superficial treatment and activation of the hydrogen-storage alloy powder had an obvious effect on improving the current efficiency for the generation of sorbitol. The most favorable results were obtained when a current density of 8 mA cm−2, a voltage of 4.0–5.0 V and a pH of 8 at a temperature of 30 °C are used. Prior to use the electrode was treated for 2 h at 80 °C with a solution containing KBH4 (0.5 mol/l), KF (0.5 mol/l) and KOH (6 mol/l). Under optimized conditions the current efficiency for sorbitol by electrolyzing glucose exceeded 90%. The yield of sorbitol was around 80%. The lifetime of the electrode was tested and analyzed, and methods of regeneration are discussed.