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- Title
The structure and electrochemical characteristics of La0.67Mg0.33 (Ni0.8Co0.1Mn0.1)x (x=2.5–5.0) multiphase alloys for nickel-metal hydride batteries.
- Authors
Xinbo Zhang; Danzi Sun; Wenya Yin; Yujun Chai; Minshou Zhao
- Abstract
This paper presents results concerning structure and electrochemical characteristics of the La0.67Mg0.33 (Ni0.8Co0.1Mn0.1)x (x=2.5–5.0) alloy. It can be found from the result of the Rietveld analyses that the structures of the alloys change obviously with increasing x from 2.5 to 5.0. The main phase of the alloys with x=2.5–3.5 is LaMg2Ni9 phase with a PuNi3-type rhombohedral structure, but the main phase of the alloys with x=4.0–5.0 is LaNi5phase with a CaCu5-type hexagonal structure. Furthermore, the phase ratio, lattice parameter and cell volume of the LaMg2Ni9phase and the LaNi5 phase change with increasing x. The electrochemical studies show that the maximum discharge capacity increases from 214.7 mAh/g (x=2.5) to 391.1 mAh/g (x=3.5) and then decreases to 238.5 mAh/g (x=5.0). As the discharge current density is 1,200 mA/g, the high rate dischargeability (HRD) increases from 51.1% (x=2.5) to 83.7% (x=3.5) and then decreases to 71.6% (x=5.0). Moreover, the exchange current density (I0) of the alloy electrodes first increases and then decrease with increasing x from 2.5 to 5.0, which is consistent with the variation of the HRD. The cell volume reduces with increasing x in the alloys, which is detrimental to hydrogen diffusion and accordingly decreases the low-temperature dischargeability of the alloy electrodes.
- Publication
Journal of Solid State Electrochemistry, 2006, Vol 10, Issue 4, p236
- ISSN
1432-8488
- Publication type
Article
- DOI
10.1007/s10008-005-0672-8