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Open AccessEditorial

Research in Nickel/Metal Hydride Batteries 2017

by Kwo-Hsiung Young

Batteries 2018, 4(1), 9; https://doi.org/10.3390/batteries4010009 - 12 Feb 2018

Cited by 23 | Viewed by 8956

Abstract

Continuing from a special issue in Batteries in 2016, nineteen new papers focusing on recent research activities in the field of nickel/metal hydride (Ni/MH) batteries have been selected for the 2017 Special Issue of Ni/MH Batteries. These papers summarize the international joint-efforts in [...] Read more.

Continuing from a special issue in Batteries in 2016, nineteen new papers focusing on recent research activities in the field of nickel/metal hydride (Ni/MH) batteries have been selected for the 2017 Special Issue of Ni/MH Batteries. These papers summarize the international joint-efforts in Ni/MH battery research from BASF, Wayne State University, Michigan State University, FDK Corp. (Japan), Institute for Energy Technology (Norway), Central South University (China), University of Science and Technology Beijing (China), Zhengzhou University of Light Industry (China), Inner Mongolia University of Science and Technology (China), Shenzhen Highpower (China), and University of the Witwatersrand (South Africa) from 2016–2017 through reviews of AB₂ metal hydride alloys, Chinese and EU Patent Applications, as well as descriptions of research results in metal hydride alloys, nickel hydroxide, electrolyte, and new cell type, comparison work, and projections of future works. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

Research

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1139 KiB

Open AccessArticle

Performance Comparison of Rechargeable Batteries for Stationary Applications (Ni/MH vs. Ni–Cd and VRLA)

by Michael A. Zelinsky, John M. Koch and Kwo-Hsiung Young

Batteries 2018, 4(1), 1; https://doi.org/10.3390/batteries4010001 - 25 Dec 2017

Cited by 29 | Viewed by 11345

Abstract

The stationary power market, particularly telecommunications back-up (telecom) applications, is dominated by lead-acid batteries. A large percentage of telecom powerplants are housed in outdoor enclosures where valve-regulated lead-acid (VRLA) batteries are commonly used because of their low-maintenance design. Batteries in these enclosures can [...] Read more.

The stationary power market, particularly telecommunications back-up (telecom) applications, is dominated by lead-acid batteries. A large percentage of telecom powerplants are housed in outdoor enclosures where valve-regulated lead-acid (VRLA) batteries are commonly used because of their low-maintenance design. Batteries in these enclosures can be exposed to temperatures which can exceed 70 °C, significantly reducing battery life. Nickel–cadmium (Ni–Cd) batteries have traditionally been deployed in hotter locations as a high-temperature alternative to VRLA. This paper compares the performances of nickel/metal hydride (Ni/MH), Ni–Cd, and VRLA batteries in a simulated telecom environment according to published testing standards. Among these three choices, Ni/MH batteries showed the best overall performance, suggesting substantially longer operating life in high temperature stationary use. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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2585 KiB

Open AccessArticle

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

by Shuli Yan, Jean Nei, Peifeng Li, Kwo-Hsiung Young and K. Y. Simon Ng

Batteries 2017, 3(4), 41; https://doi.org/10.3390/batteries3040041 - 18 Dec 2017

Cited by 7 | Viewed by 7088

Abstract

The effects of Cs₂CO₃ 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) [...] Read more.

The effects of Cs₂CO₃ 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 Cs₂CO₃ 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 Cs₂CO₃ to the electrolyte improved cycle stability (for all three alloys) and discharge capacity (for the Al-containing alloys); moreover, in the 0.33 M Cs₂CO₃ + 6.44 M KOH electrolyte, the discharge capacity of Mg₅₂Ni₃₉Co₃Mn₆ 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 Cs₂CO₃ on the physical and chemical properties of Mg₅₂Ni₃₉Co₃Mn₆ 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 Cs₂CO₃ 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 Cs₂CO₃-containing electrolyte, and was considered to be the main cause of the reduction in capacity degradation during cycling. Also, the Cs₂CO₃ 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 Cs₂CO₃ was deemed optimal in this study. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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10830 KiB

Open AccessArticle

Electron Backscatter Diffraction Studies on the Formation of Superlattice Metal Hydride Alloys

by Shuli Yan, Kwo-Hsiung Young, Xin Zhao, Zhi Mei and K. Y. Simon Ng

Batteries 2017, 3(4), 40; https://doi.org/10.3390/batteries3040040 - 13 Dec 2017

Cited by 4 | Viewed by 6708

Abstract

Microstructures of a series of La-Mg-Ni-based superlattice metal hydride alloys produced by a novel method of interaction of a LaNi₅ alloy and Mg vapor were studied using a combination of X-ray energy dispersive spectroscopy and electron backscatter diffraction. The conversion rate of [...] Read more.

Microstructures of a series of La-Mg-Ni-based superlattice metal hydride alloys produced by a novel method of interaction of a LaNi₅ alloy and Mg vapor were studied using a combination of X-ray energy dispersive spectroscopy and electron backscatter diffraction. The conversion rate of LaNi₅ increased from 86.8% into 98.2%, and the A₂B₇ phase abundance increased from 42.5 to 45.8 wt % and reduced to 39.2 wt % with the increase in process time from four to 32 h. During the first stage of reaction, Mg formed discrete grains with the same orientation, which was closely related to the orientation of the host LaNi₅ alloy. Mg then diffused through the ab-phase of LaNi₅ and formed the AB₂, AB₃, and A₂B₇ phases. Diffusion of Mg stalled at the grain boundary of the host LaNi₅ alloy. Good alignments in the c-axis between the newly formed superlattice phases and LaNi₅ were observed. The density of high-angle grain boundary decreased with the increase in process time and was an indication of lattice cracking. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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3498 KiB

Open AccessArticle

A Ni/MH Pouch Cell with High-Capacity Ni(OH)₂

by Shuli Yan, Tiejun Meng, Kwo-Hsiung Young and Jean Nei

Batteries 2017, 3(4), 38; https://doi.org/10.3390/batteries3040038 - 4 Dec 2017

Cited by 7 | Viewed by 7401

Abstract

Electrochemical performances of a high-capacity and long life β-α core-shell structured Ni_0.84Co_0.12Al_0.04(OH)₂ as the positive electrode active material were tested in a pouch design and compared to those of a standard β-Ni_0.91 [...] Read more.

Electrochemical performances of a high-capacity and long life β-α core-shell structured Ni_0.84Co_0.12Al_0.04(OH)₂ as the positive electrode active material were tested in a pouch design and compared to those of a standard β-Ni_0.91Co_0.045Zn_0.045(OH)₂. The core-shell materials were fabricated with a continuous co-precipitation process, which created an Al-poor core and an Al-rich shell during the nucleation and particle growth stages, respectively. The Al-rich shell became α-Ni(OH)₂ after electrical activation and remained intact through the cycling. Pouch cells with the high-capacity β-α core-shell positive electrode material show higher charge acceptances and discharge capacities at 0.1C, 0.2C, 0.5C, and 1C, improved self-discharge performances, and reduced internal and surface charge-transfer resistances, at both room temperature and −10 °C when compared to those with the standard positive electrode material. While the high capacity of the core-shell material can be attributed to the α phase with a multi-electron transfer capability, the improvement in high-rate capability (lower resistance) is caused by the unique surface morphology and abundant interface sites at the β-α grain boundaries. Gravimetric energy densities of pouch cells made with the high-capacity and standard positive materials are 127 and 110 Wh·kg⁻¹, respectively. A further improvement in capacity is expected via the continued optimization of pouch design and the use of high-capacity metal hydride alloy. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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Open AccessArticle

Effects of Boron-Incorporation in a V-Containing Zr-Based AB₂ Metal Hydride Alloy

by Shiuan Chang, Kwo-Hsiung Young, Taihei Ouchi, Jean Nei and Xin Wu

Batteries 2017, 3(4), 36; https://doi.org/10.3390/batteries3040036 - 14 Nov 2017

Cited by 9 | Viewed by 6420

Abstract

In this study, boron, a metalloid element commonly used in semiconductor applications, was added in a V-containing Zr-based AB₂ metal hydride alloy. In general, as the boron content in the alloy increased, the high-rate dischargeability, surface exchange current, and double-layer capacitance first [...] Read more.

In this study, boron, a metalloid element commonly used in semiconductor applications, was added in a V-containing Zr-based AB₂ metal hydride alloy. In general, as the boron content in the alloy increased, the high-rate dischargeability, surface exchange current, and double-layer capacitance first decreased and then increased whereas charge-transfer resistance and dot product of charge-transfer resistance and double-layer capacitance changed in the opposite direction. Electrochemical and gaseous phase characteristics of two boron-containing alloys, with the same boron content detected by the inductively coupled plasma optical emission spectrometer, showed significant variations in performances due to the difference in phase abundance of a newly formed tetragonal V₃B₂ phase. This new phase contributes to the increases in electrochemical high-rate dischargeability, surface exchange current, charge-transfer resistances at room, and low temperatures. However, the V₃B₂ phase does not contribute to the hydrogen storage capacities in either gaseous phase and electrochemical environment. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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Open AccessArticle

Performance Comparison between AB₅ and Superlattice Metal Hydride Alloys in Sealed Cells

by John M. Koch, Kwo-Hsiung Young, Jean Nei, Chaolan Hu and Benjamin Reichman

Batteries 2017, 3(4), 35; https://doi.org/10.3390/batteries3040035 - 6 Nov 2017

Cited by 8 | Viewed by 6239

Abstract

High-power cylindrical nickel metal/hydride batteries using a misch metal-based Al-free superlattice alloy with a composition of La_11.3Pr_1.7Nd_5.1Mg_4.5Ni_63.6Co_13.6Zr_0.2 were fabricated and evaluated against those using a standard AB₅ metal hydride [...] Read more.

High-power cylindrical nickel metal/hydride batteries using a misch metal-based Al-free superlattice alloy with a composition of La_11.3Pr_1.7Nd_5.1Mg_4.5Ni_63.6Co_13.6Zr_0.2 were fabricated and evaluated against those using a standard AB₅ metal hydride alloy. At room temperature, cells made with the superlattice alloy showed a 40% lower internal resistance and a 59% lower surface charge-transfer resistance compared to cells made with the AB₅ alloy. At a low temperature (−10 °C), cells made with the superlattice alloy demonstrated an 18% lower internal resistance and a 60% lower surface charge-transfer resistance compared to cells made with the AB₅ alloy. Cells made with the superlattice alloy exhibited a better charge retention at −10 °C. A cycle life comparison in a regular cell configuration indicated that the Al-free superlattice alloy contributes to a shorter cycle life as a result of the pulverization from the lattice expansion of the main phase. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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Open AccessArticle

Comparison among Constituent Phases in Superlattice Metal Hydride Alloys for Battery Applications

by Kwo-Hsiung Young, Taihei Ouchi, Jean Nei, John M. Koch and Yu-Ling Lien

Batteries 2017, 3(4), 34; https://doi.org/10.3390/batteries3040034 - 31 Oct 2017

Cited by 11 | Viewed by 7140

Abstract

The effects of seven constituent phases—CeNi₃, NdNi₃, Nd₂Ni₇, Pr₂Ni₇, Sm₅Ni₁₉, Nd₅Co₁₉, and CaCu₅—on the gaseous phase and electrochemical characteristics of a [...] Read more.

The effects of seven constituent phases—CeNi₃, NdNi₃, Nd₂Ni₇, Pr₂Ni₇, Sm₅Ni₁₉, Nd₅Co₁₉, and CaCu₅—on the gaseous phase and electrochemical characteristics of a superlattice metal hydride alloy made by induction melting with a composition of Sm₁₄La_5.7Mg_4.0Ni₇₃Al_3.3 were studied through a series of annealing experiments. With an increase in annealing temperature, the abundance of non-superlattice CaCu₅ phase first decreases and then increases, which is opposite to the phase abundance evolution of Nd₂Ni₇—the phase with the best electrochemical performance. The optimal annealing condition for the composition in this study is 920 °C for 5 h. Extensive correlation studies reveal that the A₂B₇ phase demonstrates higher gaseous phase hydrogen storage and electrochemical discharge capacities and better battery performance in high-rate dischargeability, charge retention, and cycle life. Moreover, the hexagonal stacking structure is found to be more favorable than the rhombohedral structure. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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4512 KiB

Open AccessFeature PaperArticle

Effects of Alkaline Pre-Etching to Metal Hydride Alloys

by Tiejun Meng, Kwo-Hsiung Young, Chaolan Hu and Benjamin Reichman

Batteries 2017, 3(4), 30; https://doi.org/10.3390/batteries3040030 - 5 Oct 2017

Cited by 9 | Viewed by 6732

Abstract

The responses of one AB₅, two AB₂, four A₂B₇, and one C14-related body-centered-cubic (BCC) metal hydrides to an alkaline-etch (45% KOH at 110 °C for 2 h) were studied by internal resistance, X-ray diffraction, scanning [...] Read more.

The responses of one AB₅, two AB₂, four A₂B₇, and one C14-related body-centered-cubic (BCC) metal hydrides to an alkaline-etch (45% KOH at 110 °C for 2 h) were studied by internal resistance, X-ray diffraction, scanning electron microscope, inductively coupled plasma, and AC impedance measurements. Results show that while the etched rare earth–based AB₅ and A₂B₇ alloys surfaces are covered with hydroxide/oxide (weight gain), the transition metal–based AB₂ and BCC-C14 alloys surfaces are corroded and leach into electrolyte (weight loss). The C14-predominated AB₂, La-only A₂B₇, and Sm-based A₂B₇ showed the most reduction in the internal resistance with the alkaline-etch process. Etched A₂B₇ alloys with high La-contents exhibited the lowest internal resistance and are suggested for use in the high-power application of nickel/metal hydride batteries. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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Open AccessArticle

Cell Performance Comparison between C14- and C15-Predomiated AB₂ Metal Hydride Alloys

by Kwo-Hsiung Young, John M. Koch, Chubin Wan, Roman V. Denys and Volodymyr A. Yartys

Batteries 2017, 3(4), 29; https://doi.org/10.3390/batteries3040029 - 25 Sep 2017

Cited by 17 | Viewed by 6741

Abstract

The performance of cylindrical cells made from negative electrode active materials of two selected AB₂ metal hydride chemistries with different dominating Laves phases (C14 vs. C15) were compared. Cells made from Alloy C15 showed a higher high-rate performance and peak power with [...] Read more.

The performance of cylindrical cells made from negative electrode active materials of two selected AB₂ metal hydride chemistries with different dominating Laves phases (C14 vs. C15) were compared. Cells made from Alloy C15 showed a higher high-rate performance and peak power with a corresponding sacrifice in capacity, low-temperature performance, charge retention, and cycle life when compared with the C14 counterpart (Alloy C14). Annealing of the Alloy C15 eliminated the ZrNi secondary phase and further improved the high-rate and peak power performance. This treatment on Alloy C15 showed the best low-temperature performance, but also contributed to a less-desirable high-temperature voltage stand and an inferior cycle stability. While the main failure mode for Alloy C14 in the sealed cell is the formation of a thick oxide layer that prevents gas recombination during overcharge and consequent venting of the cell, the failure mode for Alloy C15 is dominated by continuous pulverization related to the volumetric changes during hydride formation and hysteresis in the pressure-composition-temperature isotherm. The leached-out Mn from Alloy C15 formed a high density of oxide deposits in the separator, leading to a deterioration in charge retention performance. Large amounts of Zr were found in the positive electrode of the cycled cell containing Alloy C15, but did not appear to harm cell performance. Suggestions for further composition and process optimization for Alloy C15 are also provided. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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Open AccessArticle

Fe-Substitution for Ni in Misch Metal-Based Superlattice Hydrogen Absorbing Alloys—Part 2. Ni/MH Battery Performance and Failure Mechanisms

by Tiejun Meng, Kwo-Hsiung Young, Jean Nei, John M. Koch and Shigekazu Yasuoka

Batteries 2017, 3(3), 28; https://doi.org/10.3390/batteries3030028 - 18 Sep 2017

Cited by 4 | Viewed by 6607

Abstract

The electrochemical performance and failure mechanisms of Ni/MH batteries made with a series of the Fe-substituted A₂B₇ superlattice alloys as the negative electrodes were investigated. The incorporation of Fe does not lead to improved cell capacity or cycle life at [...] Read more.

The electrochemical performance and failure mechanisms of Ni/MH batteries made with a series of the Fe-substituted A₂B₇ superlattice alloys as the negative electrodes were investigated. The incorporation of Fe does not lead to improved cell capacity or cycle life at either room or low temperature, although Fe promotes the formation of a favorable Ce₂Ni₇ phase. Fe-substitution was found to inhibit leaching of Al from the metal hydride negative electrode and promote leaching of Co, which could potentially extend the cycle life of the positive electrode. The failure mechanisms of the cycled cells with the Fe-substituted superlattice hydrogen absorbing alloys were analyzed by scanning electron microscopy, energy dispersive spectroscopy and inductively coupled plasma analysis. The failure of cells with Fe-free and low Fe-content alloys is mainly attributed to the pulverization of the metal hydride alloy. Meanwhile, severe oxidation/corrosion of the negative electrode is observed for cells with high Fe-content alloys, resulting in increased internal cell resistance, formation of micro-shortages in the separator and eventual cell failure. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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Open AccessArticle

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

by Kwo-Hsiung Young, Taihei Ouchi, Jean Nei and Shiuan Chang

Batteries 2017, 3(3), 26; https://doi.org/10.3390/batteries3030026 - 9 Sep 2017

Cited by 9 | Viewed by 7364

Abstract

A combination of analytic tools and electrochemical testing was employed to study the contributions of Palladium (Pd) in a Zr-based AB₂ metal hydride alloy (Ti₁₂Zr_22.8V₁₀ Cr_7.5Mn_8.1Co₇Ni_32.2Al_0.4). Pd [...] Read more.

A combination of analytic tools and electrochemical testing was employed to study the contributions of Palladium (Pd) in a Zr-based AB₂ metal hydride alloy (Ti₁₂Zr_22.8V₁₀ Cr_7.5Mn_8.1Co₇Ni_32.2Al_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. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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Open AccessArticle

Comparison of C14- and C15-Predomiated AB₂ Metal Hydride Alloys for Electrochemical Applications

by Kwo-Hsiung Young, Jean Nei, Chubin Wan, Roman V. Denys and Volodymyr A. Yartys

Batteries 2017, 3(3), 22; https://doi.org/10.3390/batteries3030022 - 28 Jul 2017

Cited by 36 | Viewed by 10238

Abstract

Herein, we present a comparison of the electrochemical hydrogen-storage characteristics of two state-of-art Laves phase-based metal hydride alloys (Zr_21.5Ti_12.0V_10.0Cr_7.5Mn_8.1Co_8.0Ni_32.2Sn_0.3Al_0.4 vs. Zr_25.0Ti_6.5V_3.9 [...] Read more.

Herein, we present a comparison of the electrochemical hydrogen-storage characteristics of two state-of-art Laves phase-based metal hydride alloys (Zr_21.5Ti_12.0V_10.0Cr_7.5Mn_8.1Co_8.0Ni_32.2Sn_0.3Al_0.4 vs. Zr_25.0Ti_6.5V_3.9Mn_22.2Fe_3.8Ni_38.0La_0.3) prepared by induction melting and hydrogen decrepitation. The relatively high contents of lighter transition metals (V and Cr) in the first composition results in an average electron density below the C14/C15 threshold

(e / a ~ 6.9)

and produces a C14-predominated structure, while the average electron density of the second composition is above the C14/C15 threshold and results in a C15-predominated structure. From a combination of variations in composition, main phase structure, and degree of homogeneity, the C14-predominated alloy exhibits higher storage capacities (in both the gaseous phase and electrochemical environment), a slower activation, inferior high-rate discharge, and low-temperature performances, and a better cycle stability compared to the C15-predominated alloy. The superiority in high-rate dischargeability in the C15-predominated alloy is mainly due to its larger reactive surface area. Annealing of the C15-predominated alloy eliminates the ZrNi secondary phase completely and changes the composition of the La-containing secondary phase. While the former change sacrifices the synergetic effects, and degrades the hydrogen storage performance, the latter may contribute to the unchanged surface catalytic ability, even with a reduction in total volume of metallic nickel clusters embedded in the activated surface oxide layer. In general, the C14-predominated alloy is more suitable for high-capacity and long cycle life applications, and the C15-predominated alloy can be used in areas requiring easy activation, and better high-rate and low-temperature performances. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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Open AccessArticle

Hydrogen Storage Characteristics and Corrosion Behavior of Ti₂₄V₄₀Cr₃₄Fe₂ Alloy

by Jimoh Mohammed Abdul, Lesley Hearth Chown, Jamiu Kolawole Odusote, Jean Nei, Kwo-Hsiung Young and Woli Taiye Olayinka

Batteries 2017, 3(2), 19; https://doi.org/10.3390/batteries3020019 - 14 Jun 2017

Cited by 5 | Viewed by 8016

Abstract

In this work, we investigated the effects of heat treatment on the microstructure, hydrogen storage characteristics and corrosion rate of a Ti₃₄V₄₀Cr₂₄Fe₂ alloy. The arc melted alloy was divided into three samples, two of which were [...] Read more.

In this work, we investigated the effects of heat treatment on the microstructure, hydrogen storage characteristics and corrosion rate of a Ti₃₄V₄₀Cr₂₄Fe₂ alloy. The arc melted alloy was divided into three samples, two of which were separately quartz-sealed under vacuum and heated to 1000 °C for 1 h; one of these samples was quenched and the other furnace-cooled to ambient temperature. The crystal structures of the samples were studied via X-ray diffractometry and scanning electron microscopy. Hydrogenation/dehydrogenation characteristics were investigated using a Sievert apparatus. Potentiostat corrosion tests on the alloys were performed using an AutoLab^® corrosion test apparatus and electrochemical cell. All samples exhibited a major body-center-cubic (BCC) and some secondary phases. An abundance of Laves phases that were found in the as-cast sample reduced with annealing and disappeared in the quenched sample. Beside suppressing Laves phase, annealing also introduced a Ti-rich phase. The corrosion rate, maximum absorption, and useful capacities increased after both heat treatments. The annealed sample had the highest absorption and reversible capacity. The plateau pressure of the as-cast alloy increased after quenching. The corrosion rate increased from 0.0004 mm/y in the as-cast sample to 0.0009 mm/y after annealing and 0.0017 mm/y after quenching. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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Open AccessArticle

Fabrications of High-Capacity Alpha-Ni(OH)₂

by Kwo-Hsiung Young, Lixin Wang, Shuli Yan, Xingqun Liao, Tiejun Meng, Haoting Shen and William C. Mays

Batteries 2017, 3(1), 6; https://doi.org/10.3390/batteries3010006 - 8 Mar 2017

Cited by 52 | Viewed by 16843

Abstract

Three different methods were used to produce α-Ni(OH)₂ with higher discharge capacities than the conventional β-Ni(OH)₂, specifically a batch process of co-precipitation, a continuous process of co-precipitation with a phase transformation step (initial cycling), and an overcharge at low temperature. [...] Read more.

Three different methods were used to produce α-Ni(OH)₂ with higher discharge capacities than the conventional β-Ni(OH)₂, specifically a batch process of co-precipitation, a continuous process of co-precipitation with a phase transformation step (initial cycling), and an overcharge at low temperature. All three methods can produce α-Ni(OH)₂ or α/β mixed-Ni(OH)₂ with capacities higher than that of conventional β-Ni(OH)₂ and a stable cycle performance. The second method produces a special core–shell β-Ni(OH)₂/α-Ni(OH)₂ structure with an excellent cycle stability in the flooded half-cell configuration, is innovative and also already mass-production ready. The core–shell structure has been investigated by both scanning and transmission electron microscopies. The shell portion of the particle is composed of α-Ni(OH)₂ nano-crystals embedded in a β-Ni(OH)₂ matrix, which helps to reduce the stress originating from the lattice expansion in the β-α transformation. A review on the research regarding α-Ni(OH)₂ is also included in the paper. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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Open AccessArticle

Ionic Liquid-Based Non-Aqueous Electrolytes for Nickel/Metal Hydride Batteries

by Tiejun Meng, Kwo-Hsiung Young, Diana F. Wong and Jean Nei

Batteries 2017, 3(1), 4; https://doi.org/10.3390/batteries3010004 - 6 Feb 2017

Cited by 37 | Viewed by 12613

Abstract

The voltage of an alkaline electrolyte-based battery is often limited by the narrow electrochemical stability window of water (1.23 V). As an alternative to water, ionic liquid (IL)-based electrolyte has been shown to exhibit excellent proton conducting properties and a wide electrochemical stability [...] Read more.

The voltage of an alkaline electrolyte-based battery is often limited by the narrow electrochemical stability window of water (1.23 V). As an alternative to water, ionic liquid (IL)-based electrolyte has been shown to exhibit excellent proton conducting properties and a wide electrochemical stability window, and can be used in proton conducting batteries. In this study, we used IL/acid mixtures to replace the 30 wt % KOH aqueous electrolyte in nickel/metal hydride (Ni/MH) batteries, and verified the proton conducting character of these mixtures through electrochemical charge/discharge experiments. Dilution of ILs with acetic acid was found to effectively increase proton conductivity. By using 2 M acetic acid in 1-ethyl-3-methylimidazolium acetate, stable charge/discharge characteristics were obtained, including low charge/discharge overpotentials, a discharge voltage plateau at ~1.2 V, a specific capacity of 161.9 mAh·g⁻¹, and a stable cycling performance for an AB₅ metal hydride anode with a (Ni,Co,Zn)(OH)₂ cathode. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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Open AccessArticle

Fe-Substitution for Ni in Misch Metal-Based Superlattice Hydrogen Absorbing Alloys—Part 1. Structural, Hydrogen Storage, and Electrochemical Properties

by Kwo-Hsiung Young, Taihei Ouchi, Jean Nei and Shigekazu Yasuoka

Batteries 2016, 2(4), 34; https://doi.org/10.3390/batteries2040034 - 21 Nov 2016

Cited by 7 | Viewed by 8113

Abstract

The effects of Fe partially replacing Ni in a misch metal-based superlattice hydrogen absorbing alloy (HAA) were studied. Addition of Fe increases the lattice constants and abundance of the main Ce₂Ni₇ phase, decreases the NdNi₃ phase abundance, and increases [...] Read more.

The effects of Fe partially replacing Ni in a misch metal-based superlattice hydrogen absorbing alloy (HAA) were studied. Addition of Fe increases the lattice constants and abundance of the main Ce₂Ni₇ phase, decreases the NdNi₃ phase abundance, and increases the CaCu₅ phase when the Fe content is above 2.3 at%. For the gaseous phase hydrogen storage (H-storage), Fe incorporation does not change the storage capacity or equilibrium pressure, but it does decrease the change in both entropy and enthalpy. With regard to electrochemistry, >2.3 at% Fe decreases both the full and high-rate discharge capacities due to the deterioration in both bulk transport (caused by decreased secondary phase abundance and consequent lower synergetic effect) and surface electrochemical reaction (caused by the lower volume of the surface metallic Ni inclusions). In a low-temperature environment (−40 °C), although Fe increases the reactive surface area, it also severely hinders the ability of the surface catalytic, leading to a net increase in surface charge-transfer resistance. Even though Fe increases the abundance of the beneficial Ce₂Ni₇ phase with a trade-off for the relatively unfavorable NdNi₃ phase, it also deteriorates the electrochemical performance due to a less active surface. Therefore, further surface treatment methods that are able to increase the surface catalytic ability in Fe-containing superlattice alloys and potentially reveal the positive contributions that Fe provides structurally are worth investigating in the future. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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7962 KiB

Open AccessFeature PaperReview

C14 Laves Phase Metal Hydride Alloys for Ni/MH Batteries Applications

by Kwo-Hsiung Young, Shiuan Chang and Xinting Lin

Batteries 2017, 3(3), 27; https://doi.org/10.3390/batteries3030027 - 14 Sep 2017

Cited by 28 | Viewed by 12187

Abstract

C14 Laves phase alloys play a significant role in improving the performance of nickel/metal hydride batteries, which currently dominate the 1.2 V consumer-type rechargeable battery market and those for hybrid electric vehicles. In the current study, the properties of C14 Laves phase based [...] Read more.

C14 Laves phase alloys play a significant role in improving the performance of nickel/metal hydride batteries, which currently dominate the 1.2 V consumer-type rechargeable battery market and those for hybrid electric vehicles. In the current study, the properties of C14 Laves phase based metal hydride alloys are reviewed in relation to their electrochemical applications. Various preparation methods and failure mechanisms of the C14 Laves phase based metal hydride alloys, and the influence of all elements on the electrochemical performance, are discussed. The contributions of some commonly used constituting elements are compared to performance requirements. The importance of stoichiometry and its impact on electrochemical properties is also included. At the end, a discussion section addresses historical hurdles, previous trials, and future directions for implementing C14 Laves phase based metal hydride alloys in commercial nickel/metal hydride batteries. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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6671 KiB

Open AccessReview

Reviews of European Patents on Nickel/Metal Hydride Batteries

by Shiuan Chang, Kwo-Hsiung Young and Yu-Ling Lien

Batteries 2017, 3(3), 25; https://doi.org/10.3390/batteries3030025 - 26 Aug 2017

Cited by 11 | Viewed by 9815

Abstract

Patent applications in the field of nickel/metal hydride (Ni/MH) batteries are reviewed to provide a solid technology background and directions for future developments. As the fourth review article in the series of investigations into intellectual properties in this area, this article focuses on [...] Read more.

Patent applications in the field of nickel/metal hydride (Ni/MH) batteries are reviewed to provide a solid technology background and directions for future developments. As the fourth review article in the series of investigations into intellectual properties in this area, this article focuses on 126 patent applications filed by European companies at the European Patent Office, while the earlier articles dealt with those from USA, Japan, and China. The history and current status of the key companies in the Ni/MH battery business are briefly discussed. These companies are categorized by their main roles in the industry, i.e., battery manufacturer, metal hydride alloy supplier, separator supplier, and others. While some European companies are pioneers in bringing the Ni/MH product to customers, others have made significant contributions to the development of the technology, especially in the button cell, bipolar cell, and separator areas. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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Open AccessReview

Reviews on Chinese Patents Regarding the Nickel/Metal Hydride Battery

by Kwo-Hsiung Young, Xiaojuan Cai and Shiuan Chang

Batteries 2017, 3(3), 24; https://doi.org/10.3390/batteries3030024 - 20 Aug 2017

Cited by 11 | Viewed by 16619

Abstract

Both the patents issued and applications filed in China regarding nickel/metal hydride (Ni/MH) battery technology are reviewed in the article. Selective works from 39 battery manufactures, 9 metal hydride alloy suppliers, 13 Ni(OH)₂ suppliers, 20 hardware suppliers, 19 system integrators, universities, and [...] Read more.

Both the patents issued and applications filed in China regarding nickel/metal hydride (Ni/MH) battery technology are reviewed in the article. Selective works from 39 battery manufactures, 9 metal hydride alloy suppliers, 13 Ni(OH)₂ suppliers, 20 hardware suppliers, 19 system integrators, universities, and 12 research institutes are included. China being the country that produces the most Ni/MH batteries is relatively weak in the innovation part of intellectual properties when compared to the US and Japan. However, it produces very many patents in the areas of cell structure optimization and production processes. Designs of high-capacity, high-power, and low-cost cells are compared from different manufacturers. Full article

(This article belongs to the Special Issue Nickel Metal Hydride Batteries 2017)

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