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Article Dans Une Revue Journal of Solid State Electrochemistry Année : 2021

Phase structure and electrochemical characteristics of CaNi4.7Mn0.3 hydrogen storage alloy by mechanical alloying

Résumé

In this paper, we study systematically the effect of ball/powder weight ratio on the morphological, structural, and electrochemical properties of CaNi4.7Mn0.3 powder alloy by mechanical milling. The CaNi4.7Mn0.3 alloy powder is elaborated for an optimal milling time of 40 h with 8:1 and 12:1 ball/powder weight ratios. The X-ray diffraction (XRD) characterization shows that the CaNi4.7Mn0.3 alloy powder is characterized by a nanocrystalline/amorphous crystallographic state and exhibits two major Ni and CaNi3 phases irrespective of the ball/powder weight ratio. The CaNi4.7Mn0.3 electrode activates rapidly in the first cycle regardless of the ball/powder weight ratio, and the best value of maximum discharge capacity is obtained for an 8:1 ratio (125 mAh g−1). The values of diffusion coefficient/mean grain size squared ratio DHa2, Nernst’s potential E0, and exchange current density I0 at the first activation cycle are the best for 8:1 ball/powder weight ratio. After activation, the discharge capacity decreases exponentially regardless of the ball/powder weight ratio. Indeed, the capacity loss and the degradation rate after 50th cycle are about 71%, 10.71 cycle−1 and 53%, 2.95 cycle−1 for 8:1 and 12:1, respectively. The evolution of the DHa2 ratio, E0, and I0 during the cycling is in good agreement with that of the discharge capacity. The highest values of the diffusion coefficient DH, Nernst’s potential E0, and exchange current density I0 after 50th cycle are observed for 8:1 ball/powder weight ratio.
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Dates et versions

hal-03456180 , version 1 (29-11-2021)

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Citer

Youssef Dabaki, Chokri Khaldi, Omar El Kedim, Noureddine Fenineche, Jilani Lamloumi. Phase structure and electrochemical characteristics of CaNi4.7Mn0.3 hydrogen storage alloy by mechanical alloying. Journal of Solid State Electrochemistry, 2021, 1008, pp.5090 (12). ⟨10.1007/s10008-021-05090-x⟩. ⟨hal-03456180⟩
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