Studies on Incorporation of Mg in Zr-Based AB2 Metal Hydride Alloys

Chang, Shiuan; Kim, Young; Ouchi, T.; Meng, Tiejun; Nei, Jean; Wu, Xin

doi:10.3390/batteries2020011

Cited by 19 publications

(24 citation statements)

References 80 publications

(77 reference statements)

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“…Therefore, we believe the decrease in remaining capacity during desorption (that correlates to a more complete desorption) results from the presence of the catalytic TiNi phase (either through an increase in abundance or an increase in the Pd-content in TiNi). Similar phenomenon has also been found in the study of the Mg-incorporated C14-predominated alloys [7]. Slope factor is defined as the ratio of desorption capacity between 0.01 and 0.5 MPa to total desorption capacity, and a higher slope factor corresponds to a flatter PCT isotherm.…”

Section: Pct Analysissupporting

confidence: 80%

“…Both the charge-transfer resistance (R) and double-layer capacitance (C) were obtained from the semi-circle in the Cole-Cole plot (plot of the negative imaginary part vs. the real part of impedance with varying frequency). While R is closely related to the speed of electrochemical reaction, C is proportional to the reactive surface area, and their product (RC) can be interpreted as the surface catalytic ability without any contribution from the surface area [7,9,142]. These calculated values are listed in Table 7 and plotted with the amounts of Pd, Ce [9], and Nd [10] present in the C14 MH alloys in Figure 14.…”

Section: Electrochemical and Magnetics Propertiesmentioning

confidence: 99%

“…of the activated MH alloy. The average size of Ni clusters can also be estimated by the strength of the applied magnetic field that corresponds to half of the MS value (H1/2) [7]. The magnetic properties of several key MH alloys were compared in an earlier publication [1].…”

Section: Magnetic Susceptibilitymentioning

confidence: 99%

“…Work regarding substitution of C14 Laves phase MH alloys started at the first row of transition metals [3][4][5][6] and proceeded to several non-transition metals (for example, Mg [7], La [8], Ce [9], and Nd [10]). Palladium (Pd), one of the two elements (the other is Vanadium (V)) with hydrogen-storage (H-storage) capabilities at room temperature (the heats of hydride formation for Pd and V are −20 [11] and −33.5 kJ·mol −1 [12], respectively), is very special among all possible substitution candidates.…”

Section: Introductionmentioning

confidence: 99%

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Increase in the Surface Catalytic Ability by Addition of Palladium in C14 Metal Hydride Alloy

Kim

Ouchi²,

Nei³

et al. 2017

Batteries

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A combination of analytic tools and electrochemical testing was employed to study the contributions of Palladium (Pd) in a Zr-based AB 2 metal hydride alloy (Ti 12 Zr 22.8 V 10 Cr 7.5 Mn 8.1 Co 7 Ni 32.2 Al 0.4 ). Pd enters the A-site of both the C14 and C15 Laves phases and shrinks the unit cell volumes, which results in a decrease of both gaseous phase and electrochemical hydrogen storage capacities. On the other hand, the addition of Pd benefits both the bulk transport of hydrogen and the surface electrochemical reaction. Improvements in high-rate dischargeability and low-temperature performances are solely due to an increase in surface catalytic ability. Addition of Pd also decreases the surface reactive area, but such properties can be mediated through incorporation of additional modifications with rare earth elements. A review of Pd-addition to other hydrogen storage materials is also included.

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Section: Pct Analysissupporting

confidence: 80%

Section: Electrochemical and Magnetics Propertiesmentioning

confidence: 99%

Section: Magnetic Susceptibilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Increase in the Surface Catalytic Ability by Addition of Palladium in C14 Metal Hydride Alloy

Kim

Ouchi²,

Nei³

et al. 2017

Batteries

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“…Cole-Cole plots obtained from the alternating current (AC) impedance measurements are shown in Figure 6. The reported equivalent circuit model for Ni-MH batteries using Mg-based alloy anodes is shown in Figure 7 [63][64][65][66][67]. Constant phase elements are used in this circuit model, due to the inhomogeneity properties of the electrode surface, such as porosity and roughness.…”

Section: Effects Of Cs 2 Co 3 Addition On Mgni Alloymentioning

confidence: 99%

Effects of Cs2CO3 Additive in KOH Electrolyte Used in Ni/MH Batteries

Yan

Nei²,

et al. 2017

Batteries

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Abstract:The effects of Cs 2 CO 3 addition in a KOH-based electrolyte were investigated for applications in nickel/metal hydride batteries. Both MgNi-based and Laves phase-related body-centered cubic solid solution metal hydride alloys were tested as the anode active materials, and sintered β-Ni(OH) 2 was used as the cathode active material. Certain amounts of Cs 2 CO 3 additive in the KOH-based electrolyte improved the electrochemical performances compared with a conventional pure KOH electrolyte. For example, with Laves phase-related body-centered cubic alloys, the addition of Cs 2 CO 3 to the electrolyte improved cycle stability (for all three alloys) and discharge capacity (for the Al-containing alloys); moreover, in the 0.33 M Cs 2 CO 3 + 6.44 M KOH electrolyte, the discharge capacity of Mg 52 Ni 39 Co 3 Mn 6 increased to 132%, degradation decreased to 87%, and high-rate dischargeability stayed the same compared with the conventional 6.77 M KOH electrolyte. The effects of Cs 2 CO 3 on the physical and chemical properties of Mg 52 Ni 39 Co 3 Mn 6 were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, inductively coupled plasma, and electrochemical impedance spectroscopy. The results from these analyses concluded that Cs 2 CO 3 addition changed both the alloy surface and bulk composition. A fluffy layer containing carbon was found covering the metal particle surface after cycling in the Cs 2 CO 3 -containing electrolyte, and was considered to be the main cause of the reduction in capacity degradation during cycling. Also, the Cs 2 CO 3 additive promoted the formations of the C-O and C=O bonds on the alloy surface. The C-O and C=O bonds were believed to be active sites for proton transfer during the electrochemical process, with the C-O bond being the more effective of the two. Both bonds contributed to a higher surface catalytic ability. The addition of 0.33 M Cs 2 CO 3 was deemed optimal in this study.

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