Improvement in the electrochemical properties of gas atomized AB2 metal hydride alloys by hydrogen annealing

Young, K.; Ouchi, T.; Banik, A.; Koch, J.; Fetcenko, M.A.

doi:10.1016/j.ijhydene.2010.12.051

Cited by 24 publications

(19 citation statements)

References 54 publications

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“…For example, a solid-state battery with a thin solid separator [262] and ultra-high-power application with a very thin separator require a spherical MH alloy shape, which can be produced using GA techniques. Superlattice alloy with Mg inside cannot tolerate the Mg-vaporization because of the large surface area of the powder produced in the GA process, whereas GA with an associated annealing process already been successfully developed for AB 2 MH alloy [62]. The battery/fuel cell combination requires a MH alloy operated at intermediate temperature range • C) [263].…”

Section: Discussionmentioning

confidence: 99%

“…In the case of AB2 MH alloys, non-Laves secondary phases improve the electrochemical properties of an alloy [56] through synergetic effects [57] and are diminished by annealing treatments [58][59][60][61]. Therefore, annealing is not required for AB2 MH alloys, except for those prepared by GA and with a surface oxide layer, which can be reduced to the metallic state by annealing in hydrogen [62] (Figure 11c). Annealing in Ar was also improved the capacity of GA- [63] and MS- [64] produced AB2 MH alloys because of the ability to increase the surface crystallinity.…”

Section: Annealingmentioning

confidence: 99%

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

2017

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Annealingmentioning

confidence: 99%

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

2017

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“…Furthermore, the annealed C15 (C15A) has even larger crystallites. The increase in crystallite size after annealing is a common observation in Laves phase-based MH alloys [61,75]. …”

Section: X-ray Diffractometer Analysismentioning

confidence: 93%

“…The composition of several representative areas (identified by Roman numerals) in the SEM micrographs were studied by EDS, and the results are summarized in Table 6. SEM micrographs of the C14 alloy shows a very typical multi-phase C14-C15-Zr x Ni y microstructure, which has been extensively studied with transmission electron microscopy (TEM) [76,77] and electron backscattering diffraction (EBSD) [75]. Occasional ZrO 2 inclusions are also seen in the C14 alloy and act as oxygen scavengers [78], which may contribute positively to the bulk diffusion of hydrogen and provide surface protection against oxidation by the electrolyte [79].…”

Section: Scanning Electron Microscope/energy Dispersive Spectroscopy mentioning

confidence: 99%

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

Kim

Nei²,

Wan

et al. 2017

Batteries

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Abstract:Herein, we present a comparison of the electrochemical hydrogen-storage characteristics of two state-of-art Laves phase-based metal hydride alloys (Zr 21.5 (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.

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“…In this paper, we propose to combine GA and annealing in hydrogen (AH) processes to further extend the cycle life of the Cu-containing AB 5 alloys. Similar work has been performed on the Laves phase based AB 2 alloys and the results were very encouraging [19,20]. While GA alone provides advantages of lowering production cost and extending cycle life, the additional hydrogen annealing further improves the capacity, formation, high-power, and low-temperature performance of these MH alloys.…”

Section: Introductionmentioning

confidence: 58%