The as-cast Mg2Ni-type Mg20–xYxNi10 (x=0, 1, 2, 3 and 4) electrode alloys were prepared by vacuum induction melting. Subsequently, the as-cast alloys were mechanically milled in a planetary-type ball mill. The analys...The as-cast Mg2Ni-type Mg20–xYxNi10 (x=0, 1, 2, 3 and 4) electrode alloys were prepared by vacuum induction melting. Subsequently, the as-cast alloys were mechanically milled in a planetary-type ball mill. The analyses of scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM) reveal that nanocrystalline and amorphous structure can be obtained by mechanical milling, and the amount of amorphous phase increases with milling time prolonging. The electrochemical measurements show that the discharge capacity of Y0 alloy increases with milling time prolonging, while that of the Y-substituted alloys has a maximum value in the same condition. The cycle stabilities of the alloys decrease with milling time prolonging. The effect of milling time on the electrochemical kinetics of the alloys is related to Y content. Whenx=0, the high rate discharge ability, diffusion coefficient of hydrogen atom, limiting current density and charge transfer rate all increase with milling time prolonging, but the results are exactly opposite whenx=3.展开更多
La-Mg-Ni-Mn-based AB2-type La（1–x）CexMgNi（3.5）Mn（0.5）（x=0–0.4） alloys were prepared by melt spinning technology. The detections of X-ray diffraction（XRD） and scanning electron microscopy（SEM） indicated t...La-Mg-Ni-Mn-based AB2-type La（1–x）CexMgNi（3.5）Mn（0.5）（x=0–0.4） alloys were prepared by melt spinning technology. The detections of X-ray diffraction（XRD） and scanning electron microscopy（SEM） indicated that the experimental alloys consisted of a major phase LaMgNi4 and a secondary phase LaNi5. With spinning rate growing, the abundance of LaMgNi4 phase increased and that of LaNi5 phase decreased. Moreover, with the melt spinning rate increasing, both the lattice constants and cell volumes increased, and further accelerated the grains refinement of the alloys. The electrochemical tests showed that the as-spun alloys possessed excellent capability of activation, achieving the maximum discharge capacities just at the first cycling without any activation needed. As for the as-spun alloys, its discharge potential characteristics could be improved obviously by adopting the technology of melt spinning. In addition, the melt spinning raised electrochemical cycle stability of the alloys, the main reason was that the melt spinning enhanced the anti-pulverization ability of the alloys. With spinning rate increasing, the discharge capacity of the alloys presented a tendency to increase firstly then decrease. Moreover, the electrochemical kinetics of the alloys showed the same trend under fixed condition.展开更多
基金Projects(51161015,51371094)supported by the National Natural Science Foundation of China
文摘The as-cast Mg2Ni-type Mg20–xYxNi10 (x=0, 1, 2, 3 and 4) electrode alloys were prepared by vacuum induction melting. Subsequently, the as-cast alloys were mechanically milled in a planetary-type ball mill. The analyses of scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM) reveal that nanocrystalline and amorphous structure can be obtained by mechanical milling, and the amount of amorphous phase increases with milling time prolonging. The electrochemical measurements show that the discharge capacity of Y0 alloy increases with milling time prolonging, while that of the Y-substituted alloys has a maximum value in the same condition. The cycle stabilities of the alloys decrease with milling time prolonging. The effect of milling time on the electrochemical kinetics of the alloys is related to Y content. Whenx=0, the high rate discharge ability, diffusion coefficient of hydrogen atom, limiting current density and charge transfer rate all increase with milling time prolonging, but the results are exactly opposite whenx=3.
基金Project supported by National Natural Science Foundation of China(51161015,51371094,51471054)
文摘La-Mg-Ni-Mn-based AB2-type La（1–x）CexMgNi（3.5）Mn（0.5）（x=0–0.4） alloys were prepared by melt spinning technology. The detections of X-ray diffraction（XRD） and scanning electron microscopy（SEM） indicated that the experimental alloys consisted of a major phase LaMgNi4 and a secondary phase LaNi5. With spinning rate growing, the abundance of LaMgNi4 phase increased and that of LaNi5 phase decreased. Moreover, with the melt spinning rate increasing, both the lattice constants and cell volumes increased, and further accelerated the grains refinement of the alloys. The electrochemical tests showed that the as-spun alloys possessed excellent capability of activation, achieving the maximum discharge capacities just at the first cycling without any activation needed. As for the as-spun alloys, its discharge potential characteristics could be improved obviously by adopting the technology of melt spinning. In addition, the melt spinning raised electrochemical cycle stability of the alloys, the main reason was that the melt spinning enhanced the anti-pulverization ability of the alloys. With spinning rate increasing, the discharge capacity of the alloys presented a tendency to increase firstly then decrease. Moreover, the electrochemical kinetics of the alloys showed the same trend under fixed condition.
