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Study on the microstructure and electrochemical kinetic properties of MmNi4.50−xMnxCo0.45Al0.30 (0.25≤x≤0.45) hydrogen storage alloys
- Source :
- Materials Science and Engineering: B. 178:39-44
- Publication Year :
- 2013
- Publisher :
- Elsevier BV, 2013.
-
Abstract
- The phase structures, surface morphologies and electrochemical kinetic properties of MmNi4.50−xMnxCo0.45Al0.30 (Mm is the mischmetal, x = 0.25, 0.30, 0.35, 0.40 and 0.45) hydrogen storage alloys have been investigated in this paper. The X-ray diffraction (XRD) shows that all the alloys mainly consist of LaNi5 phase with CaCu5-type structure, which belongs to P6/mmm space group (central symmetry). Scanning electron microscopy (SEM) tests indicate that there are partial element segregations in the alloys. Meanwhile, energy dispersive spectrum (EDS) results display that the elements constituting Mm exist in the matrix phase in relatively larger proportion, while Mn, Al and Co tend to appear in precipitate phase. For the alloy with x = 0.35, the electrochemical performances, including discharge capacity, high-rate dischargeability (HRD) and cycling life, of the alloy electrode are better than that of other alloy electrodes. With the increase of Mn content, the exchange current density (I0) of the alloy electrodes first increases and then decreases, the hydrogen diffusion coefficient (D) of alloy electrodes gradually decreases. There is a linear correlation between HRD at a discharge current density of 1500 mA/g and I0.
- Subjects :
- Materials science
Hydrogen
Scanning electron microscope
Mechanical Engineering
Metallurgy
Alloy
Analytical chemistry
chemistry.chemical_element
Exchange current density
engineering.material
Condensed Matter Physics
Microstructure
Mischmetal
Hydrogen storage
chemistry
Mechanics of Materials
Phase (matter)
engineering
General Materials Science
Subjects
Details
- ISSN :
- 09215107
- Volume :
- 178
- Database :
- OpenAIRE
- Journal :
- Materials Science and Engineering: B
- Accession number :
- edsair.doi...........6ede4acbc6e8da916d7added36882e7b