Solid-gas and electrochemical hydrogenation properties of the La1-Nd MgNi4-Co alloys

New La1-xNdxMgNi4-yCoy (x = 0, 0.5, 1; y = 0, 0.5, 1) alloys have been synthesized by powder sintering method, and their crystal structure and hydrogen storage properties have been systematically studied. X-ray diffraction analysis showed that La1-xNdxMgNi4-yCoy alloys belong to the MgCu4Sn-type structure. Hydrogen storage capacity of the alloys is in the 1.1–1.7 wt % H range. The alloy hydrides of are stable in air at room temperature. XRD studies have shown that hydrides retain the crystalline structure of the starting alloy while increasing the cellular volume by 15–23%. Pressure–composition–temperature (PСT) measurements demonstrated that thermodynamic stability of hydrides decreases with an increasing Nd content whereas increasing Co content in the alloys leads to the increase their stability which is demonstrated by the lowering desorption plateau pressure with Co content. Electrochemical studies showed that La-rich electrode materials exhibit the maximum discharge capacity (300–330 mAh/g), but Nd-doped ones show better cyclic stability.