Preparation and Hydrogen Storage Kinetics of Nanocrystalline and Amorphous Mg20Ni10-xMx (M=Co, Cu; x=0-4) Alloys

2012 ◽  
Vol 528 ◽  
pp. 43-49
Author(s):  
Yang Huan Zhang ◽  
Zhong Hui Hou ◽  
Guo Fang Zhang ◽  
Hong Wei Shang ◽  
Feng Hu ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Electrochemical Impedance ◽  
Amorphous Structure ◽  
High Rate ◽  
Electrochemical Kinetics ◽  
Type Alloy ◽  
Hydrogen Storage Kinetics ◽  
Nanocrystalline And Amorphous ◽  
Electrochemical Hydrogen Storage ◽  
Kinetics Of

In order to obtain a nanocrystalline and amorphous structure in the Mg2Ni-type alloy, the Ni in Mg2Ni alloy has been partially substituted by M (M=Co, Cu), and the melt spinning has been used to fabricate the Mg20Ni10-xMx (M=Co, Cu; x=0-4) hydrogen storage alloys. The microstructures of the alloys were characterized by XRD, SEM and HRTEM. The effects of substituting Ni with M (M=Co, Cu) on the gaseous and electrochemical hydrogen storage kinetics of the as-spun alloys were investigated. The results indicate that the as-spun (M=Co) alloys display a nanocrystalline and amorphous structure, while the as-spun (M=Cu) alloys hold an entire nanocrystalline structure, suggesting that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. The substitution of M (M=Co, Cu) for Ni exerts a trifling impact on the hydriding kinetics of the alloys, but it renders a marked enhancement of dehydriding capacity and kinetics. Furthermore, the measurements of the high rate discharge ability (HRD) and the hydrogen diffusion coefficient (D) as well as the electrochemical impedance spectra (EIS) of the alloys exhibit that the electrochemical kinetics of the as-spun (30 m/s) alloys is significantly ameliorated by substituting Ni with M (M=Co, Cu).

Improved Physical and Electrochemical Hydrogen Storage Kinetics of the Mg20Ni10-XMx (M=Cu, Co; X=0, 4) Alloys by Melt Spinning

2012 ◽  
Vol 499 ◽  
pp. 25-30
Author(s):  
Yang Huan Zhang ◽  
Li Zhao Guo ◽  
Hong Wei Shang ◽  
Zhong Hui Hou ◽  
Ying Cai ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Melt Spinning ◽  
Nanocrystalline Structure ◽  
Amorphous Structure ◽  
High Rate ◽  
Secondary Phases ◽  
Type Alloy ◽  
Hydrogen Storage Kinetics ◽  
Electrochemical Hydrogen Storage ◽  
Kinetics Of

It has come to light that the Mg2Ni-type alloy with a nanocrystalline/amorphous structure possesses superior hydrogen storage kinetics. The Mg2Ni-type Mg20Ni10-xMx (M=Cu, Co; x=0, 4) hydrogen storage alloys were synthesized by a melt-spinning technique. The microstructures of the as-cast and spun alloys were characterized by XRD, SEM and HRTEM. The gaseous and electrochemical hydrogen storage kinetics of the alloys was measured. The results show that whatever spinning rate the as-spun (M=Cu) alloys hold an entire nanocrystalline structure. As spinning rate approaches to 20 m/s, the as-spun (M=Co) alloys display a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. Furthermore, such substitution results in the formation of secondary phases Mg2Cu and MgCo2 instead of changing the major phase of Mg2Ni. The melt spinning markedly improves the gaseous and electrochemical hydrogen storage kinetics of the alloys. The hydrogen absorption ratio (R5a ), hydrogen desorption ratio (R20d ) and the high rate discharge ability (HRD) notably mount up with the growing of the spinning rate.

Ameliorated Hydrogen Storage Kinetics of Mg20Ni7M3 (M=Co, Cu) Alloys by Melt Spinning

2012 ◽  
Vol 184-185 ◽  
pp. 880-885
Author(s):  
Yang Huan Zhang ◽  
Zhong Hui Hou ◽  
Li Cui Chen ◽  
Tai Yang ◽  
Hong Wei Shang ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Melt Spinning ◽  
Amorphous Structure ◽  
Limiting Current ◽  
Type Alloy ◽  
Hydrogen Storage Kinetics ◽  
Cu Alloys ◽  
Nanocrystalline And Amorphous ◽  
Electrochemical Hydrogen Storage ◽  
Kinetics Of

In order to obtain a nanocrystalline and amorphous structure in the Mg2Ni-type alloy, the melt spinning was applied to fabricate the Mg20Ni7M3 (M=Co, Cu) hydrogen storage alloys. The microstructures of the alloys were characterized by XRD, SEM and HRTEM. The effects of the melt spinning on the gaseous and electrochemical hydrogen storage kinetics of the alloys were investigated. The results indicate that the as-spun (M=Co) alloys display a nanocrystalline and amorphous structure as spinning rate grows to 20 m/s, while the as-spun (M=Cu) alloys hold an entire nanocrystalline structure even if a limited spinning rate is applied, suggesting that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. The melt spinning remarkably ameliorates the gaseous hydriding and dehydriding kinetics of the alloys. The hydrogen absorption ratio ( ) and hydrogen desorption ratio ( ) are enhanced from 81.9% to 94.7% and from 34.9% to 57.3% for the (M=Co) alloy, and from 57.2% to 92.8% and from 21.6% to 49.6% for the (M=Cu) alloy by raising spinning rate from 0 (as-cast was defined as the spinning rate of 0 m/s) to 30 m/s. Furthermore, the high rate discharge ability (HRD), the limiting current density (IL) and the hydrogen diffusion coefficient (D) of the alloys notably increase with the growing of the spinning rate.

Improved the Physical and Electrochemical Hydrogen Storage Kinetics of Mg2Ni-Type Alloys by Substituting Ni with Co and Melt Spinning

2011 ◽  
Vol 415-417 ◽  
pp. 1565-1571
Author(s):  
Zhi Hong Ma ◽  
Bo Li ◽  
Dong Liang Zhao ◽  
Hui Ping Ren ◽  
Guo Fang Zhang ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Melt Spinning ◽  
Nanocrystalline Structure ◽  
Secondary Phase ◽  
Amorphous Structure ◽  
Co Substitution ◽  
Hydrogen Storage Kinetics ◽  
Nanocrystalline And Amorphous ◽  
Electrochemical Hydrogen Storage ◽  
Kinetics Of

In this paper, melt-spinning technology was used for preparing Mg20Ni10-xCox (x = 0, 1, 2, 3, 4) hydrogen storage alloys. The influences of both the Co substitution and the melt spinning on the the physical and electrochemical hydrogen storage kinetics of the alloys were investigated. The XRD, SEM and TEM characterization exhibits that the as-spun Co-free alloy holds a typical nanocrystalline structure, whereas the as-spun alloys substituted by Co display a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. The Co substitution gives rise to forming secondary phase MgCo2 without altering the Mg2Ni major phase of the alloys. The measurement of the physical and electrochemical hydrogen storage kinetics of the alloys shows that both the melt spinning and the substitution of Co for Ni markedly improve the physical hydriding and dehydriding kinetics and the electrochmeical kinetics (HRD) of the alloys.

Improved Physical and Electrochemical Hydrogen Storage Kinetics of the As-Spun Mg2Ni-Type Alloys by Substituting Ni with M (M=Co, Cu)

2012 ◽  
Vol 430-432 ◽  
pp. 423-428
Author(s):  
Yang Huan Zhang ◽  
Bao Wei Li ◽  
Hui Ping Ren ◽  
Zai Guang Pang ◽  
Zhong Hui Hou ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Melt Spinning ◽  
Nanocrystalline Structure ◽  
Hydrogen Desorption ◽  
Amorphous Structure ◽  
High Rate ◽  
Desorption Kinetics ◽  
Hydrogen Storage Kinetics ◽  
Electrochemical Hydrogen Storage ◽  
Kinetics Of

In order to improve the physical and electrochemical hydrogen storage kinetics of the Mg2Ni-type alloys, Ni in the alloy was partially substituted by M (M=Co, Cu). Melt-spinning technology was used for the preparation of the Mg20Ni10-xMx (M=Co, Cu; x=0, 1, 2, 3, 4) hydrogen storage alloys. The structures of the as-cast and spun alloys are characterized by XRD, SEM and TEM. The physical and electrochemical hydrogen storage kinetics of the alloys is measured. The results show that the as-spun (M=Cu) alloys hold an entire nanocrystalline structure, whereas the as-spun (M=Co) alloys exhibit a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. The substitution of M (M=Co, Cu) for Ni engenders an insignificant effect on the hydrogen absorption kinetics of the alloys, but it markedly ameliorates the hydrogen desorption kinetics of the alloys and the high rate discharge ability. With an increase of the M (M=Co, Cu) content from 0 to 4, the hydrogen desorption ratio ( ) is enhanced form 20.0% to 65.43% for the as-spun (20 m/s) alloy (M=Co), and from 20.0% to 52.88% for the as-spun (20 m/s) alloy (M=Cu).

Hydriding and Dehydriding Kinetics of Nanocrystalline and Amorphous Mg20Ni6M4 (M=Cu, Co) Alloys

2012 ◽  
Vol 512-515 ◽  
pp. 1389-1394
Author(s):  
Yang Huan Zhang ◽  
Guo Fang Zhang ◽  
Hong Wei Shang ◽  
Zhong Hui Hou ◽  
Ying Cai ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Melt Spinning ◽  
Nanocrystalline Structure ◽  
Amorphous Structure ◽  
Type Alloy ◽  
Hydrogen Storage Kinetics ◽  
Cu Alloy ◽  
Nanocrystalline And Amorphous ◽  
Kinetics Of ◽  
Co Alloys

It was well known that the Mg2Ni-type alloy with a nanocrystalline/amorphous structure possesses superior hydrogen storage kinetics. In order to obtain a nanocrystalline and amorphous structure, the melt spinning was applied to prepare the Mg2Ni-type Mg20Ni6M4 (M=Cu, Co) hydrogen storage alloys. The microstructures of the as-cast and spun alloys were characterized by XRD, SEM and HRTEM. The gaseous hydriding and dehydriding kinetics of the alloys was measured. The results show that the as-spun (M=Co) alloys display a nanocrystalline and amorphous structure as spinning rate approaches to 20 m/s, while the as-spun (M=Cu) alloys hold an entire nanocrystalline structure whatever spinning rate is, suggesting that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. The melt spinning markedly improves the gaseous hydrogen storage kinetics of the alloys. As the spinning rate grows from 0 (as-cast was defined as the spinning rate of 0 m/s) to 30 m/s, the hydrogen absorption saturation ratio ( ) is enhanced from 57.7% to 91.4% for the (M=Cu) alloy and from 77.1% to 93.5% for the (M=Co) alloy. And hydrogen desorption ratio ( ) is raised from 28.7% to 59.0% for the (M=Cu) alloy and from 54.5% to 70.2% for the (M=Co) alloy, respectively.

Enhanced Electrochemical Hydrogen Storage Characteristics of the as-Spun Mg2Ni-Type Alloys by Substituting Ni with M (M=Cu, Co)

2012 ◽  
Vol 457-458 ◽  
pp. 572-577
Author(s):  
Yang Huan Zhang ◽  
Bao Wei Li ◽  
Hui Ping Ren ◽  
Zai Guang Pang ◽  
Zhong Hui Hou ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Melt Spinning ◽  
Nanocrystalline Structure ◽  
Amorphous Structure ◽  
High Rate ◽  
Electrochemical Performances ◽  
Secondary Phases ◽  
Nanocrystalline And Amorphous ◽  
Electrochemical Hydrogen Storage ◽  
Rate Discharge

Mg2Ni-type Mg20Ni10-xMx (M=Cu, Co; x=0, 1, 2, 3, 4) electrode alloys with nanocrystalline and amorphous structure were synthesized by melt-spinning technique. The microstructures of the as-spun alloys were characterized by XRD, SEM and HRTEM. The electrochemical hydrogen storage properties of the experimental alloys were measured. The obtained results show that the as-spun (M=Cu) alloys hold an entire nanocrystalline structure, whereas the as-spun (M=Co) alloys display a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. Furthermore, such substitution results in the formation of secondary phases Mg2Cu and MgCo2 instead of changing the major phase of Mg2Ni. The substitution of M (M=Cu, Co) for Ni markedly improves the electrochemical performances of the alloys, involving the discharge capacity and the cycle stability as well as the high rate discharge ability.

Enhanced Electrochemical Hydrogen Storage Characteristics of Mg2Ni-Type Alloy by Substituting Mg with La

2011 ◽  
Vol 399-401 ◽  
pp. 1461-1466
Author(s):  
Hui Ping Ren ◽  
Bao Wei Li ◽  
Yin Zhang ◽  
Zai Guang Pang ◽  
Zhong Hui Hou ◽  
...  
Keyword(s):  
Melt Spinning ◽  
Amorphous Structure ◽  
High Rate ◽  
Electrochemical Performances ◽  
Type Alloy ◽  
Major Phase ◽  
Nanocrystalline And Amorphous ◽  
Ni Alloy ◽  
Electrochemical Hydrogen Storage ◽  
Cast Alloys

The melt-spinning technique is applied to the preparation of the nanocrystalline and amorphous Mg2Ni-type alloys with nominal compositions of Mg2-xLaxNi (x=0, 0.2, 0.4, 0.6). The as-spun alloy ribbons possessing a continuous length, a thickness of about 30 μm and a width of about 25 mm were prepared. The structures of the as-spun alloy ribbons are characterized by XRD, SEM and TEM. The electrochemical performances of the as-spun alloy ribbons are measured by an automatic galvanostatic system. The results show that no amorphous structure is detected in the as-spun Mg2Ni alloy, whereas the as-spun alloys substituted by La display a nanocrystalline and amorphous structure, confirming that the substitution of La for Mg notably intensifies the amorphous forming ability of the Mg2Ni-type alloy. For La content x≤0.2, the substitution of La for Mg brings to the formation of LaMg3 and La2Mg17 phases without changing the Mg2Ni major phase. But as La content is increased to x≥0.4, such substitution changes the major phase of the alloys to (La, Mg)Ni3+LaMg3. The discharge capacity of the as-cast alloys grows with the increasing amount of La substitution, whereas that of the as-spun alloys yields a maximum value with variation of La content. Furthermore, the substitution of La for Mg remarkably enhances the cycle stability of the as-cast and spun alloys. And the high rate dischargeability (HRD) of the as-cast and spun alloys first mounts up then falls with rising La content.

Electrochemical Cycle Stability and Kinetics of the As-Cast and Spun La0.75−xZrxMg0.25Ni3.2Co0.2Al0.1 (x = 0-0.2) Alloys

2012 ◽  
Vol 560-561 ◽  
pp. 1016-1020
Author(s):  
Yang Huan Zhang ◽  
Guo Fang Zhang ◽  
Xiao Gang Liu ◽  
Le Le Chen ◽  
Zhong Hui Hou ◽  
...  
Keyword(s):  
Melt Spinning ◽  
Electrode Materials ◽  
Electrochemical Impedance ◽  
Amorphous Structure ◽  
High Rate ◽  
Electrochemical Kinetics ◽  
Partial Substitution ◽  
Electrochemical Impedance Spectrum ◽  
Cycle Stability ◽  
Kinetics Of

The poor electrochemical cycle stability of Re-Mg-Ni system A2B7-type electrode alloys has limited their practical application as the negative electrode materials of Ni-MH battery. In order to improve the electrochemical cycle stability of the La-Mg-Ni system A2B7-type electrode alloys, the partial substitution of Zr for La has been performed. The La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1 (x = 0–0.2) electrode alloys were fabricated by casting and melt-spinning. The microstructures and the electrochemical cycle stability and kinetics of the alloys were investigated. The structure characterized by XRD, SEM and HRTEM reveals that the as-cast and spun alloys have a multiphase structure, composing of two main phases (La, Mg)2Ni7 and LaNi5 as well as a residual phase LaNi2. The as-spun Zr-free alloy displays an entire nanocrystalline structure, but a like amorphous structure is detected in the as-spun alloy substituted by Zr, suggesting that the substitution of Zr for La facilitates the formation of an amorphous structure. The electrochemical measurement indicates that both the substitution of Zr for La and the melt spinning remarkably ameliorate electrochemical cycle stability of the alloys. Furthermore, the high rate discharge ability (HRD), the electrochemical impedance spectrum (EIS) and the potential-step measurements all indicate that both of the melt spinning and the Zr substitution bring on a notable decline of the electrochemical kinetics of the alloys.

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