Influences of the substitution of Fe for Ni on structures and electrochemical performances of the as-cast and quenched La0.7Mg0.3Co0.45Ni2.55−xFex (x=0–0.4) electrode alloys

Rare earth–Mg–Ni-based hydrogen storage alloys as negative electrode materials for Ni/MH batteries

“…The reduction of Mg volatilization to ensure a stable and homogeneous composition is of interest. Several preparation techniques such as powder sintering [22][23][24][25][26][27]30,[51][52][53][54][55][56], vacuum magnetic levitation induction melting [28,29,, arc melting [93][94][95][96][97], rapid solidification [89,[98][99][100][101][102][103], spark plasma sintering [104], laser sintering [105] and ball milling [106][107][108][109] have been used to produce R-Mg-Ni-based hydrogen storage electrode alloys. Structures of the corresponding alloys have been characterized and identified by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM).…”

“…All sintered samples contained a PuNi 3 -type primary phase and a few impurity phases like LaNi 5 , MgNi 2 and La 2 Ni 7 , etc. At the same time, a number of La-Mg-Ni-based alloys with refined crystal grains were prepared by the rapid quenching technique [98][99][100][101][102][103][104]. XRD reveled that all quenched alloys possess a multiphase structure and TEM images showed that part of samples tended toward amorphization.…”

“…XRD reveled that all quenched alloys possess a multiphase structure and TEM images showed that part of samples tended toward amorphization. Also, R-Mg-Ni-based alloys can be prepared by arc melting constituent elements on a water-cooled copper hearth under an argon atmosphere [100][101][102][103][104].…”

The relationship between discharge capacity of LaNi5 type hydrogen storage alloys and formation enthalpy

“…To improve the performance and lower the cost of LaNi 5 alloys, efforts have been made to find suitable substitutes for cobalt, nickel and lanthanum, but the experimental work associated with finding the optimal element from such a wide range of possibilities is tedious. As reported in literatures, Al partial substitution for Ni can improve the activation energies, and decrease the plateau pressure, but impair the hydrogen storage capacity obviously [1][2][3][4][5][6]. Partial replacement of Ni by Cu, Cr can decrease the plateau pressure and increase the unit cell volume and formation enthalpy [3,7].…”

Influences of low-Ti substitution for La and Mg on the electrochemical and kinetic characteristics of AB3-type hydrogen storage alloy electrodes

“…In recent years, the AB 3 -type hydrogen storage materials of the La-Mg-Ni alloy system were investigated extensively as negative electrode candidates for MH-Ni secondary batteries because of their much higher discharge capacity [4][5][6]. For example, the maximum electrochemical discharge capacity of La 0.7 Mg 0.3 Ni 2.8 Co 0.5 alloy reached 410 mAh/g, which was 30% higher than that of the conventional AB 5 -type hydrogen storage alloys.…”