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Application of Nanocrystalline LaNi_5-type hydrogen absorbing Alloys in Ni-MH_x Batteries

Journal of Rare Earths 2004年第5期22卷 596-599页

作者： Jurczyk M Nowak M Institute of materials Science and Engineering Poznan University of Technology 60-965 Poznan PolandInstitute of Materials Science and Engineering Poznan University of Technology 60-965 Poznan Poland

The structure and electrochemical properties of nanocrystalline LaNi_5-type alloys were studied. These materials were prepared by mechanical alloying (MA) followed by annealing. The properties of hydrogen host materials can be modified substantially by alloying to obtain the desired storage characteristics. It was found that the partial substitution of Ni by Al or Mn in LaNi_(5-x)M_x alloy leads to an increase in discharge capacity. The alloying elements such as Al, Mn and Co greatly improved the cycle life of LaNi_5 material. For example, in the nanocrystalline LaNi_(3.75)Mn_(0.75)Al_(0.25)Co_(0.25) powder, discharge capacity up to 258 mAh·g^(-1) was measured (at 40 mA·g^(-1) discharge current). Furthermore, the effect of the graphite coating on the structure of some nanocrystalline alloys and the electrodes characteristics were investigated. The mechanical coating with graphite effectively reduced the degradation rate of the studied electrode materials. The combination of a nanocrystalline LaNi_5-type hydride electrodes and a nickel positive electrode to form a Ni-MH battery, was successful.

关键词： hydrogen absorbing materials electrode materials nanocrystalline materials Ni-MH_x batteries rare earths

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Enhancing magnetic properties of anisotropic NdDyFeCoNbCuB powder by applying magnetic field at high temperature during hydrogen desorption

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Rare Metals 2010年第5期29卷 480-485页

作者： LUO Jianjun P. De Rango D. Fruchart MEI Jinna HU Rui LI Jinshan ZHOU Lian State Key Laboratory of Solidification Processing Northwestern Polytechnic University Xi'an 710072 China Matière Condensée Matériaux et Fonctions ( MCMF ) lnstitut Néel CNRS BP 166 38042 Grenoble Cedex 9 Francec Consortium de Recherches pour l'Emergence de Technologies Avancées ( CRETA ) CNRS BP 166 38042 Grenoble Cedex 9 France

Anisotropic powder was prepared with precursor （NdDy）-（FeCoNbCu）-B sintered magnets by hydrogen decrepitation, desorption, and subsequent annealing treatment. The hydrogen desorption was performed in magnetic fields of 0, 1, 3, and 5 T. The orientation of tetragonal phase grains of the powder was evaluated from the hysteresis loops measured by extraction magnetometer. Residual hydrogen content of the powder was evaluated by thermal-magnetic analysis. The powder with Hcj, Br, and （BH）max of 1138 kA.m^-1, 1.029 T, and 172.5 kJ.m^-3, respectively, was achieved under the condition of the magnetic field of 3 T. Magnetic properties of the powder, especially, the remanence of the powder, are enhanced upon magnetic fields, which is due to better orientation of powder particles and less residual hydrogen in the powder resulted from the magnetic field during the hydrogen desorption process.

关键词： permanent magnets hydrogen absorbing materials anisotropy magnetic measurements magnetic properties

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Towards understanding the influence of Mg content on phase transformations in the La3-xMgxNi9 alloys by in-situ neutron powder diffraction study

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Progress in Natural Science:materials International 2021年第5期31卷 698-704页

作者： Chu Bin Wan R.V.Denys V.A.Yartys Institute for Energy Technology University of Science and Technology Beijing HYSTORSYS AS

The present work is focused on the studies of the phase-structural transformations in the La3-xMgxNi9（x = 1.0, 1.1 and 1.2） alloys as active materials of negative electrodes in the Nickel-Metal Hydride（Ni/MH） batteries. The phase equilibria and phase-structural transformations in the alloys were probed by in situ neutron powder diffraction（NPD） at the temperatures ranging from 300 K to 1273 K using the measurements of the equilibrated alloys at 8 setpoint temperatures of 300, 973, 1073, 1123, 1173, 1223, 1248 and 1273 *** by induction melting initial alloys were found to be multi-phase structured, containing up to 6 individual intermetallic compounds with different stoichiometric compositions. With the increase of the temperature and holding time, various transformations took place in the studied alloys. These included the formations and transformations of super-stacking intermetallics with variable ratios（La + Mg）/Ni, 1:3, 2:7 and 5:*** increasing temperatures, several systematic changes took place.（a） Abundances of（La,Mg）2Ni4AB2and（La,Mg）Ni3AB3type intermetallics gradually decreased before they melted/decomposed above 1073 K;（b） The（La,Mg）2Ni7A2B7type intermetallics began to decrease in abundances above 1123 K;（c） The transformation in the（La,Mg）5Ni19intermetallics from 3 R to 2 H proceeded above 1223 *** increase of Mg content had no obvious influence on（La,Mg）2Ni4and（La,Mg）2Ni7phases, and corresponding reactions R1 and R3 took place at the same temperatures as in the La–Ni system. However, with increasing Mg content the melting point of（La,Mg）5Ni19phase increased while the melting point of the（La,Mg）Ni3phase it decreased, leading to the variation of the reaction temperatures of the corresponding *** present study will assist in optimizing phase-structural composition of the alloys in the La–Mg–Ni system which contain Mg-modified layered structures by tailoring the high temperature annealing conditions.

关键词： hydrogen absorbing materials Neutron powder diffraction In situ study La–Mg–Ni alloy Phase transformation

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