Special Issue "Nickel Metal Hydride Batteries"

A special issue of Batteries (ISSN 2313-0105).

Deadline for manuscript submissions: closed (15 May 2016).

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A printed edition of this Special Issue is available here.

Special Issue Editor

Dr. Kwo Young
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Guest Editor
1. Department of Chemical Engineering and Material Sciences, Wayne State University, Detroit, MI 48202, USA
2. BASF Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309, USA
Interests: metal hydride alloy; nickel/metal hydride battery; proton-conducting battery; solid-state battery; solid-state hydrogen storage
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Special Issue Information

Dear Colleagues,

Nickel metal hydride (NiMH) batteries are presently used extensively in hybrid electric vehicles (HEVs). More than 10 million HEVs based on NiMH batteries have been manufactured and driven, and NiMH battery chemistry is expected to continue dominating the HEV market with its proven abuse tolerance, wide operating-temperature range, and durable service life. With the main goal of achieving higher gravimetric energy density while maintaining safety and robustness advantages, continuous efforts in improving the performances of NiMH batteries are very much needed in order to explore its possibility in other applications, such as battery-powered electric vehicles (BEV), stationary market, and more. Meanwhile, with the inherited high volumetric energy density, NiMH battery may have a chance to return to application in portable electronic devices. For this Special Issue of Batteries, papers of review, current research, and future projection in the materials, fabrication methods, cell integration and development, performance evaluation, failure analysis, and other subjects related to NiMH batteries are invited. Discussions and comments prior to manuscript submissions are also welcomed.

Dr. Kwo Young
Guest Editor

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Keywords

  • nickel metal hydride battery
  • electrochemical reaction
  • battery performance evaluation
  • hydrogen storage alloy
  • nickel hydroxide

Published Papers (20 papers)

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Editorial

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Open AccessEditorial
Research in Nickel/Metal Hydride Batteries 2016
Batteries 2016, 2(4), 31; https://doi.org/10.3390/batteries2040031 - 02 Oct 2016
Cited by 6 | Viewed by 5071
Abstract
Nineteen papers focusing on recent research investigations in the field of nickel/metal hydride (Ni/MH) batteries have been selected for this Special Issue of Batteries. These papers summarize the joint efforts in Ni/MH battery research from BASF, Wayne State University, the National Institute of [...] Read more.
Nineteen papers focusing on recent research investigations in the field of nickel/metal hydride (Ni/MH) batteries have been selected for this Special Issue of Batteries. These papers summarize the joint efforts in Ni/MH battery research from BASF, Wayne State University, the National Institute of Standards and Technology, Michigan State University, and FDK during 2015–2016 through reviews of basic operational concepts, previous academic publications, issued US Patent and filed Japan Patent Applications, descriptions of current research results in advanced components and cell constructions, and projections of future works. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)

Research

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Open AccessArticle
Studies on MgNi-Based Metal Hydride Electrode with Aqueous Electrolytes Composed of Various Hydroxides
Batteries 2016, 2(3), 27; https://doi.org/10.3390/batteries2030027 - 19 Aug 2016
Cited by 12 | Viewed by 4805
Abstract
Compositions of MgNi-based amorphous-monocrystalline thin films produced by radio frequency (RF) sputtering with a varying composition target have been optimized. The composition Mg52Ni39Co3Mn6 is identified to possess the highest initial discharge capacity of 640 mAh·g−1 [...] Read more.
Compositions of MgNi-based amorphous-monocrystalline thin films produced by radio frequency (RF) sputtering with a varying composition target have been optimized. The composition Mg52Ni39Co3Mn6 is identified to possess the highest initial discharge capacity of 640 mAh·g−1 with a 50 mA·g−1 discharge current density. Reproduction in bulk form of Mg52Ni39Co3Mn6 alloy composition was prepared through a combination of melt spinning (MS) and mechanical alloying (MA), shows a sponge-like microstructure with >95% amorphous content, and is chosen as the metal hydride (MH) alloy for a sequence of electrolyte experiments with various hydroxides including LiOH, NaOH, KOH, RbOH, CsOH, and (C2H5)4N(OH). The electrolyte conductivity is found to be closely related to cation size in the hydroxide compound used as 1 M additive to the 4 M KOH aqueous solution. The degradation performance of Mg52Ni39Co3Mn6 alloy through cycling demonstrates a strong correlation with the redox potential of the cation in the alkali hydroxide compound used as 1 M additive to the 5 M KOH aqueous solution. NaOH, CsOH, and (C2H5)4N(OH) additions are found to achieve a good balance between corrosion and conductivity performances. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Microstructure Investigation on Metal Hydride Alloys by Electron Backscatter Diffraction Technique
Batteries 2016, 2(3), 26; https://doi.org/10.3390/batteries2030026 - 01 Aug 2016
Cited by 15 | Viewed by 4523
Abstract
The microstructures of two metal hydride (MH) alloys, a Zr7Ni10 based Ti15Zr26Ni59 and a C14 Laves phase based Ti12Zr21.5V10Ni36.2Cr4.5Mn13.6Sn0.3Co2.0Al [...] Read more.
The microstructures of two metal hydride (MH) alloys, a Zr7Ni10 based Ti15Zr26Ni59 and a C14 Laves phase based Ti12Zr21.5V10Ni36.2Cr4.5Mn13.6Sn0.3Co2.0Al0.4, were studied using the electron backscatter diffraction (EBSD) technique. The first alloy was found to be composed of completely aligned Zr7Ni10 grains with a ZrO2 secondary phase randomly scattered throughout and a C15 secondary phase precipitated along the grain boundary. Two sets of orientation alignments were found between the Zr7Ni10 grains and the C15 phase: (001)Zr7Ni10A//(110)C15 and [100]Zr7Ni10A//[0 1 ¯ 1]C15, and (01 1 ¯ )Zr7Ni10B//( 1 ¯ 00)C15 and [100]Zr7Ni10B//[313]C15. The grain growth direction is close to [313]Zr7Ni10B//[ 1 ¯ 11]C15. The second alloy is predominated by a C14 phase, as observed from X-ray diffraction analysis. Both the matrix and dendrite seen through a scanning electron microscope arise from the same C14 structure with a similar chemical composition, but different orientations, as the matrix with the secondary phases in the form of intervening Zr7Ni10/Zr9Ni11/(Zr,Ni)Ti needle-like phase coated with a thin layer of C15 phase. The crystallographic orientation of the C15 phase is in alignment with the neighboring C14 phase, with the following relationships: (111)C15//(0001)C14 and [1 1 ¯ 0]C15//[11 2 ¯ 0]C14. The alignments in crystallographic orientations among the phases in these two multi-phase MH alloys confirm the cleanliness of the interface (free of amorphous region), which is necessary for the hydrogen-storage synergetic effects in both gaseous phase reaction and electrochemistry. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Open AccessArticle
The Importance of Rare-Earth Additions in Zr-Based AB2 Metal Hydride Alloys
Batteries 2016, 2(3), 25; https://doi.org/10.3390/batteries2030025 - 11 Jul 2016
Cited by 18 | Viewed by 4996
Abstract
Effects of substitutions of rare earth (RE) elements (Y, La, Ce, and Nd) to the Zr-based AB2 multi-phase metal hydride (MH) alloys on the structure, gaseous phase hydrogen storage (H-storage), and electrochemical properties were studied and compared. Solubilities of the RE atoms [...] Read more.
Effects of substitutions of rare earth (RE) elements (Y, La, Ce, and Nd) to the Zr-based AB2 multi-phase metal hydride (MH) alloys on the structure, gaseous phase hydrogen storage (H-storage), and electrochemical properties were studied and compared. Solubilities of the RE atoms in the main Laves phases (C14 and C15) are very low, and therefore the main contributions of the RE additives are through the formation of the RENi phase and change in TiNi phase abundance. Both the RENi and TiNi phases are found to facilitate the bulk diffusion of hydrogen but impede the surface reaction. The former is very effective in improving the activation behaviors. −40 °C performances of the Ce-doped alloys are slightly better than the Nd-doped alloys but not as good as those of the La-doped alloys, which gained the improvement through a different mechanism. While the improvement in ultra-low-temperature performance of the Ce-containing alloys can be associated with a larger amount of metallic Ni-clusters embedded in the surface oxide, the improvement in the La-containing alloys originates from the clean alloy/oxide interface as shown in an earlier transmission electron microscopy study. Overall, the substitution of 1 at% Ce to partially replace Zr gives the best electrochemical performances (capacity, rate, and activation) and is recommended for all the AB2 MH alloys for electrochemical applications. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Open AccessArticle
Gaseous Phase and Electrochemical Hydrogen Storage Properties of Ti50Zr1Ni44X5 (X = Ni, Cr, Mn, Fe, Co, or Cu) for Nickel Metal Hydride Battery Applications
Batteries 2016, 2(3), 24; https://doi.org/10.3390/batteries2030024 - 08 Jul 2016
Cited by 6 | Viewed by 4821
Abstract
Structural, gaseous phase hydrogen storage, and electrochemical properties of a series of the Ti50Zr1Ni44X5 (X = Ni, Cr, Mn, Fe, Co, or Cu) metal hydride alloys were studied. X-ray diffraction (XRD) and scanning electron microscopy [...] Read more.
Structural, gaseous phase hydrogen storage, and electrochemical properties of a series of the Ti50Zr1Ni44X5 (X = Ni, Cr, Mn, Fe, Co, or Cu) metal hydride alloys were studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed the multi-phase nature of all alloys, which were composed of a stoichiometric TiNi matrix, a hyperstoichiometric TiNi minor phase, and a Ti2Ni secondary phase. Improvement in synergetic effects between the main TiNi and secondary Ti2Ni phases, determined by the amount of distorted lattice region in TiNi near Ti2Ni, was accomplished by the substitution of an element with a higher work function, which consequently causes a dramatic increase in gaseous phase hydrogen storage capacity compared to the Ti50Zr1Ni49 base alloy. Capacity performance is further enhanced in the electrochemical environment, especially in the cases of the Ti50Zr1Ni49 base alloy and Ti50Zr1Ni44Co5 alloy. Although the TiNi-based alloys in the current study show poorer high-rate performances compared to the commonly used AB5, AB2, and A2B7 alloys, they have adequate capacity performances and also excel in terms of cost and cycle stability. Among the alloys investigated, the Ti50Zr1Ni44Fe5 alloy demonstrated the best balance among capacity (394 mAh·g−1), high-rate performance, activation, and cycle stability and is recommended for follow-up full-cell testing and as the base composition for future formula optimization. A review of previous research works regarding the TiNi metal hydride alloys is also included. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Open AccessArticle
First-Principles Point Defect Models for Zr7Ni10 and Zr2Ni7 Phases
Batteries 2016, 2(3), 23; https://doi.org/10.3390/batteries2030023 - 30 Jun 2016
Cited by 3 | Viewed by 4088
Abstract
Synergetic effects in multi-phased AB2 Laves-phase-based metal hydride (MH) alloys enable the access of high hydrogen storage secondary phases, despite the lower absorption/desorption kinetics found in nickel/metal hydride (Ni/MH) batteries. Alloy design strategies to further tune the electrochemical properties of these secondary [...] Read more.
Synergetic effects in multi-phased AB2 Laves-phase-based metal hydride (MH) alloys enable the access of high hydrogen storage secondary phases, despite the lower absorption/desorption kinetics found in nickel/metal hydride (Ni/MH) batteries. Alloy design strategies to further tune the electrochemical properties of these secondary phases include the use of additives and processing techniques to manipulate the chemical nature and the microstructure of these materials. It is also of particular interest to observe the engineering of constitutional point defects and how they may affect electrochemical properties and performance. The Zr7Ni10 phase appears particularly prone to point defects, and we use density functional theory (DFT) calculations coupled with a statistical mechanics model to study the theoretical point defects. The Zr2Ni7 phase appears less prone to point defects, and we use the Zr2Ni7 point defect model, as well as experimental lattice parameters, with Zr7Ni10 phases from X-ray diffraction (XRD) as points of comparison. The point defect models indicate that anti-site defects tend to form in the Zr7Ni10 phase, and that these defects form more easily in the Zr7Ni10 phase than the Zr2Ni7 phase, as expected. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Open AccessArticle
Clean Grain Boundary Found in C14/Body-Center-Cubic Multi-Phase Metal Hydride Alloys
Batteries 2016, 2(3), 22; https://doi.org/10.3390/batteries2030022 - 30 Jun 2016
Cited by 8 | Viewed by 4576
Abstract
The grain boundaries of three Laves phase-related body-center-cubic (bcc) solid-solution, metal hydride (MH) alloys with different phase abundances were closely examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and more importantly, electron backscatter diffraction (EBSD) techniques. By using EBSD, we were [...] Read more.
The grain boundaries of three Laves phase-related body-center-cubic (bcc) solid-solution, metal hydride (MH) alloys with different phase abundances were closely examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and more importantly, electron backscatter diffraction (EBSD) techniques. By using EBSD, we were able to identify the alignment of the crystallographic orientations of the three major phases in the alloys (C14, bcc, and B2 structures). This finding confirms the presence of crystallographically sharp interfaces between neighboring phases, which is a basic assumption for synergetic effects in a multi-phase MH system. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Failure Mechanisms of Nickel/Metal Hydride Batteries with Cobalt-Substituted Superlattice Hydrogen-Absorbing Alloy Anodes at 50 °C
Batteries 2016, 2(3), 20; https://doi.org/10.3390/batteries2030020 - 24 Jun 2016
Cited by 10 | Viewed by 4667
Abstract
The incorporation of a small amount of Co in the A2B7 superlattice hydrogen absorbing alloy (HAA) can benefit its electrochemical cycle life performance at both room temperature (RT) and 50 °C. The electrochemical properties of the Co-substituted A2B [...] Read more.
The incorporation of a small amount of Co in the A2B7 superlattice hydrogen absorbing alloy (HAA) can benefit its electrochemical cycle life performance at both room temperature (RT) and 50 °C. The electrochemical properties of the Co-substituted A2B7 and the failure mechanisms of cells using such alloys cycled at RT have been reported previously. In this paper, the failure mechanisms of the same alloys cycled at 50 °C are reported. Compared to that at RT, the trend of the cycle life at 50 °C versus the Co content in the Co-substituted A2B7 HAAs is similar, but the cycle life is significantly shorter. Failure analysis of the cells at 50 °C was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), and inductively coupled plasma (ICP) analysis. It was found that the elevated temperature accelerates electrolyte dry-out and the deterioration (both pulverization and oxidation) of the A2B7 negative electrode, which are major causes of cell failure when cycling at 50 °C. Cells from HAA with higher Co-content also showed micro-shortage in the separator from the debris of the corrosion of the negative electrode. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Open AccessArticle
New Type of Alkaline Rechargeable Battery—Ni-Ni Battery
Batteries 2016, 2(2), 16; https://doi.org/10.3390/batteries2020016 - 08 Jun 2016
Cited by 3 | Viewed by 4772
Abstract
The feasibility of utilizing disordered Ni-based metal hydroxide, as both the anode and the cathode materials, in alkaline rechargeable batteries was validated for the first time. Co and Mn were introduced into the hexagonal Ni(OH)2 crystal structure to create disorder and defects [...] Read more.
The feasibility of utilizing disordered Ni-based metal hydroxide, as both the anode and the cathode materials, in alkaline rechargeable batteries was validated for the first time. Co and Mn were introduced into the hexagonal Ni(OH)2 crystal structure to create disorder and defects that resulted in a conductivity increase. The highest discharge capacity of 55.6 mAh·g−1 was obtained using a commercial Li-ion cathode precursor, specifically NCM111 hydroxide, as anode material in the Ni-Ni battery. Charge/discharge curves, cyclic voltammetry (CV), X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray energy dispersive spectroscopy (EDS) analysis, and electron energy loss spectroscopy (EELS) were used to study the capacity degradation mechanism, and the segregation of Ni, Co, and Mn hydroxides in the mixed hydroxide. Further optimization of composition and control in micro-segregation are needed to increase the discharge capacity closer to the theoretical value, 578 mAh·g−1. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Studies on the Synergetic Effects in Multi-Phase Metal Hydride Alloys
Batteries 2016, 2(2), 15; https://doi.org/10.3390/batteries2020015 - 19 May 2016
Cited by 22 | Viewed by 4250
Abstract
The electrochemical reactions of multi-phase metal hydride (MH) alloys were studied using a series of Laves phase-related body-centered-cubic (BCC) Ti15.6Zr2.1V43Cr11.2Mn6.9Co1.4Ni18.5Al0.3X (X = V, B, Mg, Y, [...] Read more.
The electrochemical reactions of multi-phase metal hydride (MH) alloys were studied using a series of Laves phase-related body-centered-cubic (BCC) Ti15.6Zr2.1V43Cr11.2Mn6.9Co1.4Ni18.5Al0.3X (X = V, B, Mg, Y, Zr, Nb, Mo, La, and Nd) alloys. These alloys are composed of BCC (major), TiNi (major), C14 (minor), and Ti2Ni (minor) phases. The BCC phase was found to be responsible for the visible equilibrium pressure plateau between 0.1 MPa and 1 MPa. The plateaus belonging to the other phases occurred below 0.005 MPa. Due to the synergetic effects of other non-BCC phases, the body-centered-tetragonal (BCT) intermediate step is skipped and the face-centered-cubic (FCC) hydride phase is formed directly. During hydrogenation in both gaseous phase and electrochemistry, the non-BCC phases were first charged to completion, followed by charging of the BCC phase. In the multi-phase system, the side with a higher work function along the grain boundary is believed to be the first region that becomes hydrogenated and will not be fully dehydrided after 8 h in vacuum at 300 °C. While there is a large step at approximately 50% of the maximum hydrogen storage for the equilibrium pressure measured in gaseous phase, the charge/discharge curves measured electrochemically are very smooth, indicating a synergetic effect between BCC and non-BCC phases in the presence of voltage and charge non-neutrality. Compared to the non-BCC phases, the C14 phase benefits while the TiNi phase deteriorates the high-rate dischargeability (HRD) of the alloys. These synergetic effects are explained by the preoccupied hydrogen sites on the side of the hydrogen storage phase near the grain boundary. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Studies on Incorporation of Mg in Zr-Based AB2 Metal Hydride Alloys
Batteries 2016, 2(2), 11; https://doi.org/10.3390/batteries2020011 - 14 Apr 2016
Cited by 15 | Viewed by 4200
Abstract
Mg, the A-site atom in C14 (MgZn2), C15 (MgCu2), and C36 (MgNi2) Laves phase alloys, was added to the Zr-based AB2 metal hydride (MH) alloy during induction melting. Due to the high melting temperature of the [...] Read more.
Mg, the A-site atom in C14 (MgZn2), C15 (MgCu2), and C36 (MgNi2) Laves phase alloys, was added to the Zr-based AB2 metal hydride (MH) alloy during induction melting. Due to the high melting temperature of the host alloy (>1500 °C) and high volatility of Mg in the melt, the Mg content of the final ingot is limited to 0.8 at%. A new Mg-rich cubic phase was found in the Mg-containing alloys with a small phase abundance, which contributes to a significant increase in hydrogen storage capacities, the degree of disorder (DOD) in the hydride, the high-rate dischargeability (HRD), and the charge-transfer resistances at both room temperature (RT) and −40 °C. This phase also facilitates the activation process in measurement of electrochemical discharge capacity. Moreover, through a correlation study, the Ni content was found to be detrimental to the storage capacities, while Ti content was found to be more influential in HRD and charge-transfer resistance in this group of AB2 metal hydride (MH) alloys. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Electrochemical Open-Circuit Voltage and Pressure-Concentration-Temperature Isotherm Comparison for Metal Hydride Alloys
Batteries 2016, 2(2), 6; https://doi.org/10.3390/batteries2020006 - 23 Mar 2016
Cited by 15 | Viewed by 4054
Abstract
In this study we compared the electrochemical pressure-concentration-temperature (EPCT) method with the gaseous phase pressure-concentration-temperature (PCT) method and demonstrated the differences between the two. Experimentally, this was done by electrochemically charging/discharging the electrodes of four different metal hydride (MH) alloys. The results indicate [...] Read more.
In this study we compared the electrochemical pressure-concentration-temperature (EPCT) method with the gaseous phase pressure-concentration-temperature (PCT) method and demonstrated the differences between the two. Experimentally, this was done by electrochemically charging/discharging the electrodes of four different metal hydride (MH) alloys. The results indicate that in the PCT curve is flatter with a smaller hysteresis and a higher storage capacity compared to the EPCT curve. Moreover, while the PCT curves (up to around one third of the hydrogen storage capacity) reside in between the charge and discharge EPCT curves, the rest of the PCT curves are below the EPCT curves. Finally, we demonstrated a new calibration method based on the inflection points observed in the EPCT isotherms of a physical mixture of more than one alloy. This turning point can be used to find a preset calibration point to determine the state-of-charge. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Microstructures of the Activated Si-Containing AB2 Metal Hydride Alloy Surface by Transmission Electron Microscope
Batteries 2016, 2(1), 4; https://doi.org/10.3390/batteries2010004 - 07 Mar 2016
Cited by 7 | Viewed by 4324
Abstract
The surface microstructure of an activated Si-containing AB2 metal hydride (MH) alloy was investigated by transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS). Regions of the main AB2 and the secondary TiNi (B2 structure) phases directly underneath the surface [...] Read more.
The surface microstructure of an activated Si-containing AB2 metal hydride (MH) alloy was investigated by transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS). Regions of the main AB2 and the secondary TiNi (B2 structure) phases directly underneath the surface Zr oxide/hydroxide layers are considered electrochemically inactive. The surface of AB2 is covered, on the atomic scale, by sheets of Ni2O3 with direct access to electrolyte and voids, without the buffer oxide commonly seen in Si-free AB2 alloys. This clean oxide/bulk metal alloy interface is believed to be the main source of the improvements in the low-temperature performance of Si-containing AB2 alloys. Sporadic metallic-Ni clusters can be found in the surface Ni2O3 region. However, the density of these clusters is much lower than the Ni-inclusions found in most typical metal hydride surface oxides. A high density of nano-sized metallic Ni-inclusions (1–3 nm) is found in regions associated with the TiNi secondary phase, i.e., in the surface oxide layer and in the grain boundary, which can also contribute to enhancement of the electrochemical performance. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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A Technical Report of the Robust Affordable Next Generation Energy Storage System-BASF Program
Batteries 2016, 2(1), 2; https://doi.org/10.3390/batteries2010002 - 01 Feb 2016
Cited by 32 | Viewed by 5746
Abstract
The goal of the Robust Affordable Next Generation Energy Storage System (RANGE)-BASF program is to provide an alternative solution for the energy storage media that powers electric vehicles other than the existing Li-ion battery. With the use of a rare-earth-free metal hydride (MH) [...] Read more.
The goal of the Robust Affordable Next Generation Energy Storage System (RANGE)-BASF program is to provide an alternative solution for the energy storage media that powers electric vehicles other than the existing Li-ion battery. With the use of a rare-earth-free metal hydride (MH) as the active negative electrode material, together with a core-shell type alpha-beta nickel hydroxide as the active positive electrode and a sealed pouch design, an energy density of 145 Wh·kg−1 and cost model of $120 kWh−1 are shown to be feasible. Combined with the proven safety record and cycle stability, we have demonstrated the feasibility of using a Ni-MH battery in EV applications. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Open AccessArticle
Structure, Hydrogen Storage, and Electrochemical Properties of Body-Centered-Cubic Ti40V30Cr15Mn13X2 Alloys (X = B, Si, Mn, Ni, Zr, Nb, Mo, and La)
Batteries 2015, 1(1), 74-90; https://doi.org/10.3390/batteries1010074 - 10 Dec 2015
Cited by 13 | Viewed by 4103
Abstract
Structure, gaseous phase hydrogen storage, and electrochemical properties of a series of TiVCrMn-based body-centered-cubic (BCC) alloys with different partial substitutions for Mn with covalent elements (B and Si), transition metals (Ni, Zr, Nb, and Mo), and rare earth element (La) were investigated. Although [...] Read more.
Structure, gaseous phase hydrogen storage, and electrochemical properties of a series of TiVCrMn-based body-centered-cubic (BCC) alloys with different partial substitutions for Mn with covalent elements (B and Si), transition metals (Ni, Zr, Nb, and Mo), and rare earth element (La) were investigated. Although the influences from substitutions on structure and gaseous phase storage properties were minor, influences on electrochemical discharge capacity were significant. The first cycle capacity ranged from 16 mAh·g−1 (Si-substituted) to 247 mAh·g−1 (Mo-substituted). Severe alloy passivation in 30% KOH electrolyte was observed, and an original capacity close to 500 mAh·g−1 could possibly be achieved by Mo-substituted alloy if a non-corrosive electrolyte was employed. Surface coating of Nafion to the Mo-substituted alloy was able to increase the first cycle capacity to 408 mAh·g−1, but the degradation rate in mAh·g−1·cycle−1 was still similar to that of standard testing. Electrochemical capacity was found to be closely related to BCC phase unit cell volume and width of the an extra small pressure plateau at around 0.3 MPa on the 30 °C pressure-concentration-temperature (PCT) desorption isotherm. Judging from its high electrochemical discharge capacity, Mo was the most beneficial substitution in BCC alloys for Ni/metal hydride (MH) battery application. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Effects of Salt Additives to the KOH Electrolyte Used in Ni/MH Batteries
Batteries 2015, 1(1), 54-73; https://doi.org/10.3390/batteries1010054 - 27 Nov 2015
Cited by 13 | Viewed by 4193
Abstract
KOH-based electrolytes with different salt additives were investigated to reduce their corrosive nature toward Mg/Ni metal hydride alloys used as negative electrodes in nickel metal hydride (Ni/MH) batteries. Alkaline metal halide salts and oxyacid salts were studied as additives to the traditional KOH [...] Read more.
KOH-based electrolytes with different salt additives were investigated to reduce their corrosive nature toward Mg/Ni metal hydride alloys used as negative electrodes in nickel metal hydride (Ni/MH) batteries. Alkaline metal halide salts and oxyacid salts were studied as additives to the traditional KOH electrolyte with concentrations varying from 0.005 M to 1.77 M. Effects of the cations and anions of the additives on charge/discharge performance are discussed. The reduction potential of alkaline cations and radii of halogen anions were correlated with initial capacity and degradation of the metal hydride alloy. A synergistic effect between KOH and some oxyacid salt additives was observed and greatly influenced by the nature of the salt additives. It was suggested that both the formation of a solid film over the metal hydride surface and the promotion of proton transfer in the additives containing electrolytes led to a decreased degradation of the electrodes and an increased discharge capacity. 12 salt additives, NaC2H3O2, KC2H3O2, K2CO3, Rb2CO3, Cs2CO3, K3PO4, Na2WO4, Rb2SO4, Cs2SO4, NaF, KF, and KBr, were found to increase the corrosion resistance of the MgNi-based metal hydride alloy. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Effects of Vanadium/Nickel Contents in Laves Phase-Related Body-Centered-Cubic Solid Solution Metal Hydride Alloys
Batteries 2015, 1(1), 34-53; https://doi.org/10.3390/batteries1010034 - 20 Nov 2015
Cited by 14 | Viewed by 3799
Abstract
Structural, gaseous phase hydrogen storage, and electrochemical properties of a series of annealed (900 °C for 12 h) Laves phase-related body-centered-cubic (BCC) solid solution metal hydride (MH) alloys with vanadium/nickel (V/Ni) contents ranging from 44/18.5 to 28/34.5 were studied. As the average Ni-content [...] Read more.
Structural, gaseous phase hydrogen storage, and electrochemical properties of a series of annealed (900 °C for 12 h) Laves phase-related body-centered-cubic (BCC) solid solution metal hydride (MH) alloys with vanadium/nickel (V/Ni) contents ranging from 44/18.5 to 28/34.5 were studied. As the average Ni-content increases, C14 phase evolves into the C15 phase and a new σ-VNi phase emerges; lattice constants in BCC, C14, and TiNi phase all decrease; the main plateau pressure increases; both gaseous phase and electrochemical hydrogen storage capacities decrease; the pressure-concentration-temperature (PCT) absorption/desorption hysteresis decreases; both high-rate dischargeability (HRD) and bulk hydrogen diffusivity increase and then decrease; and the surface reaction current decreases. There is a capacity-rate tradeoff with the change in V/Ni content. Alloys with relatively lower Ni-content show higher capacities but inferior high-rate performance compared to commercially available AB5 MH alloy. Increasing the Ni-content in this BCC-based multi-phase alloy can improve the high-rate capability over AB5 alloy but with lower discharge capacities. The inferior surface reaction current in these alloys, compared to AB5, may be due to the smaller surface area, not the total volume, of the Ni clusters embedded in the surface oxide layer of the activated alloys. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Review

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Open AccessReview
Reviews on the Japanese Patent Applications Regarding Nickel/Metal Hydride Batteries
Batteries 2016, 2(3), 21; https://doi.org/10.3390/batteries2030021 - 30 Jun 2016
Cited by 16 | Viewed by 5796
Abstract
The Japanese Patent Applications filed on the topic of nickel/metal hydride (Ni/MH) batteries have been reviewed. Patent applications filed by the top nine battery manufacturers (Matsushita, Sanyo, Hitachi Maxell, Yuasa, Toshiba, FDK, Furukawa, Japan Storage, and Shin-kobe), five component suppliers (Tanaka, Mitsui, Santoku, [...] Read more.
The Japanese Patent Applications filed on the topic of nickel/metal hydride (Ni/MH) batteries have been reviewed. Patent applications filed by the top nine battery manufacturers (Matsushita, Sanyo, Hitachi Maxell, Yuasa, Toshiba, FDK, Furukawa, Japan Storage, and Shin-kobe), five component suppliers (Tanaka, Mitsui, Santoku, Japan Metals & Chemicals Co. (JMC), and Shin-Etsu), and three research institutes (Industrial Research Institute (ISI), Agency of Industrial Science and Technology (AIST), and Toyota R & D) were chosen as the main subjects for this review, based on their production volume and contribution to the field. By reviewing these patent applications, we can have a clear picture of the technology development in the Japanese battery industry. These patent applications also provide insights, know-how, and future directions for engineers and scientists working in the rechargeable battery field. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Open AccessReview
Reviews on the U.S. Patents Regarding Nickel/Metal Hydride Batteries
Batteries 2016, 2(2), 10; https://doi.org/10.3390/batteries2020010 - 12 Apr 2016
Cited by 26 | Viewed by 5004
Abstract
U.S. patents filed on the topic of nickel/metal hydride (Ni/MH) batteries have been reviewed, starting from active materials, to electrode fabrication, cell assembly, multi-cell construction, system integration, application, and finally recovering and recycling. In each category, a general description about the principle and [...] Read more.
U.S. patents filed on the topic of nickel/metal hydride (Ni/MH) batteries have been reviewed, starting from active materials, to electrode fabrication, cell assembly, multi-cell construction, system integration, application, and finally recovering and recycling. In each category, a general description about the principle and direction of development is given. Both the metal hydride (MH) alloy and nickel hydroxide as active materials in negative and positive electrodes, respectively, are reviewed extensively. Both thermal and battery management systems (BMSs) are also discussed. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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Open AccessReview
Capacity Degradation Mechanisms in Nickel/Metal Hydride Batteries
Batteries 2016, 2(1), 3; https://doi.org/10.3390/batteries2010003 - 01 Mar 2016
Cited by 31 | Viewed by 5891
Abstract
The consistency in capacity degradation in a multi-cell pack (>100 cells) is critical for ensuring long service life for propulsion applications. As the first step of optimizing a battery system design, academic publications regarding the capacity degradation mechanisms and possible solutions for cycled [...] Read more.
The consistency in capacity degradation in a multi-cell pack (>100 cells) is critical for ensuring long service life for propulsion applications. As the first step of optimizing a battery system design, academic publications regarding the capacity degradation mechanisms and possible solutions for cycled nickel/metal hydride (Ni/MH) rechargeable batteries under various usage conditions are reviewed. The commonly used analytic methods for determining the failure mode are also presented here. The most common failure mode of a Ni/MH battery is an increase in the cell impedance due to electrolyte dry-out that occurs from venting and active electrode material degradation/disintegration. This work provides a summary of effective methods to extend Ni/MH cell cycle life through negative electrode formula optimizations and binder selection, positive electrode additives and coatings, electrolyte optimization, cell design, and others. Methods of reviving and recycling used/spent batteries are also reviewed. Full article
(This article belongs to the Special Issue Nickel Metal Hydride Batteries)
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