MoS_2催化的球磨态REMg_(11)Ni(RE=Y,Sm)合金的储氢性能（英文）

制备MoS 2催化作用下的球磨态REMg11Ni-5MoS2(质量分数)(RE=Y,Sm)合金,用以比较其储氢性能。储氢性能通过多种方法测定,包括XRD、TEM、自动Sievert设备、TG和DSC。结果显示,两种球磨态的合金都具有纳米晶和非晶结构。与RE=Sm合金相比,RE=Y合金具有较大的吸氢量、较快的吸氢速率、较低的初始放氢温度、较好的放氢性能和较低的放氢活化能,其中较低的放氢活化能被视为其具备较好储氢动力学的原因。

A Comparison Study of Hydrogen Storage Thermodynamics and Kinetics of YMg11Ni Alloy Prepared by Melt Spinning and Ball Milling

Melt spinning （MS） and ball milling （BM） were employed to fabricate YMg11Ni alloy, and their structures and hydrogen storage performances were examined. The results reveal that the as-spun and as-milled alloys both exhibit the nanocrystalline and amorphous structure. The as-milled alloy shows a larger hydrogen absorption capacity as compared with the as-spun alloy. More than that, the as-milled alloy exhibits lower onset hydrogen desorption temperature than the as-spun one, which are 549.8 and 560.9 K, respectively. Additionally, the as-milled alloy shows a superior hydrogen desorption property to the as-spun one. On the basis of the time needed by desorbing hydrogen of 3 wt% H2, for the as- milled alloy, it needs 1106, 456, 343, and 180 s corresponding to hydrogen desorption temperatures of 593, 613, 633, and 653 K. However, for the as-spun alloy, the time needed is greater than 2928, 842, 356, and 197 s corresponding to the same temperatures. Hydrogen desorption activation energies of as-milled and as-spun alloys are 98.01 and 105.49 kJ/mol, respectively, which is responsible for that the as-milled alloy possesses a much faster dehydriding rate. By means of the measurement of pressure-composition-temperature （P-C-T） curves, the dehydrogenation enthalpy change of the alloys prepared by MS （△Hoe（MS）） and BM （△Hdc（BM）） is 81.84 and 79.46 kJ/mol, respectively, viz. △Hde（MS） 〉 △Hoc（BM）.

Structure and electrochemical properties of LaMgNi4-xCox(x=0-0.8)hydrogen storage electrode alloys

LaMgNi（4-x）Cox（x = 0-0.8） electrode alloys used for MH/Ni batteries were prepared by induction melting. The structures and electrochemical hydrogen storage properties of the alloys were investigated in detail.X-ray diffraction（XRD） and scanning electron microscopy（SEM） analysis show that LaMgNi4 phase and LaNi5 phase are obtained. The lattice parameters of the two phases increase first and then decrease with Co content increasing.The electrochemical properties of the alloy electrodes were measured by means of simulated battery tests. Results show that the addition of Co does not change the discharge voltage plateau of the alloy electrodes. However, the maximum discharge capacity increases from 319.9 mAh·g^-1（x = 0）to 347.5 mAh·g^-1（x = 0.4） and then decreases to331.7 mAh·g^-1（x = 0.8）. The effects of Co content on electrochemical kinetics of the alloy electrodes were also performed. The high rate dischargeability（HRD） first increases and then decreases with Co content increasing and reaches the maximum value（95.0 %） when x = 0.4. Test results of the electrochemical impedance spectra（EIS）,potentiodynamic polarization curves and constant potential step measurements of the alloy electrodes all demonstrate that when Co content is 0.4 at%, the alloy exhibits the best comprehensive electrochemical properties.

Hydrogen Storage Thermodynamics and Dynamics of Nd–Mg–NiBased Nd Mg_(12^-)Type Alloys Synthesized by Mechanical Milling

Nanocrystalline and amorphous Nd Mg_（12^-）type Nd Mg_（11）Ni＋ x wt% Ni（x=100, 200） hydrogen storage alloys were synthesized by mechanical milling. The effects of Ni content and milling time on hydrogen storage thermodynamics and dynamics of the alloys were systematically investigated. The gaseous hydrogen absorption and desorption properties were investigated by Sieverts apparatus and differential scanning calorimeter connected with a H_2 detector. Results show that increasing Ni content significantly improves hydrogen absorption and desorption kinetics of the alloys. Furthermore,varying milling time has an obvious effect on the hydrogen storage properties of the alloys. Hydrogen absorption saturation ratio（R^a_（10）; a ratio of the hydrogen absorption capacity in 10 min to the saturated hydrogen absorption capacity） of the alloys obtains the maximum value with varying milling time. Hydrogen desorption ratio（R^d_（20）, a ratio of the hydrogen desorption capacity in 20 min to the saturated hydrogen absorption capacity） of the alloys always increases with extending milling time. The improved hydrogen desorption kinetics of the alloys are considered to be ascribed to the decreased hydrogen desorption activation energy caused by increasing Ni content and milling time.

Hydrogen Storage Performances of Nanocrystalline and Amorphous NdMg11Ni+x wt% Ni （x=100, 200） Alloys Synthesized by Mechanical Milling

Nanocrystalline and amorphous NdMg12-type NdMg11Ni+x wt%Ni(x=100,200)alloys were successfully prepared through ball milling(BM).The microstructures and electrochemical properties were systematically studied to get a more comprehensive understanding of the sample alloys.The maximum discharging capacity could be obtained at only two cycles,indicating that as-milled alloys have superior activation capability.The more the Ni content,the better the electrochemical properties of the as-milled samples.To be specific,the discharge capacities of x=100 and x=200(BM 20 h)samples are 128.2 and 1030.6 mAh/g at 60 mAh/g current density,respectively,revealing that enhancement of Ni content could significantly improve the discharging capacities of the samples.Additionally,milling duration obviously influences the electrochemical properties of the samples.The discharging capacity always rises with milling duration prolonging for the x=100 sample,but that of the(x=200)sample shows a trend of first augment and then decrease.The cycling stability of the(x=100)alloy clearly decreases with extending milling duration,whereas that of the(x=200)alloy first declines and then augments under the same conditions.In addition,the high rate discharge(HRD)abilities of the sample display the maximal values as milling duration changes.The HRD(HRD=C300/C60×100%)values of the as-milled alloys(x=100,200)are 80.24%and 85.17%,respectively.

Structure and electrochemical hydrogen storage characteristics of nanocrystalline and amorphous MgNi-type alloy synthesized by mechanical milling

Both element substitution and surface modification were utilized to enhance the electrochemical performances of Mg–Ni-based alloys. Nanocrystalline and amorphous -Mg1?xCexNi0.9Al0.1 (x?=?0–0.08)?+?50 wt.% Ni hydrogen storage alloys were synthesized through mechanical milling. The sample alloys show excellent activation property and have good electrochemi-cal hydrogenation and dehydrogenation property at normal temperature. The discharge capacity has a peak value with Ce content varying which is 461.6 mAh/g for 10-h milled alloy, while that of -Ce0.04 alloy augments from 352.6 to 536.9 mAh/g with milling time extending from 5 to 30 h. Cycle stability is conspicuously improved with Ce content and milling duration augment. To be specific, when cycle number is fixed at 100, the capacity retention rate augments from 41% to 72% after Ce dosage rising from 0 to 0.08 for the 10-h milled alloy and from 58% to 76% after milling duration extending from 5 to 30 h for -Ce0.06 alloy. Additionally, the electrochemical kinetics of the alloys own peak values with Ce proportion varying;however, they always rise with milling duration extending.