Electrochemical performance of compounds Gd6Mn23−xNix (x = 0–1.4)

Alloys with composition Gd6Mn23−xNix (x = 0, 0.4, 1.0, 1.2 and 1.4) are prepared and examined by X-ray diffraction technique. The Gd6Mn23−xNix (x = 0, 0.4, 1.0, 1.2 and 1.4) compounds crystallize in cubic Th6Mn23-type structure with space group Fm3¯m (No. 225). The electrochemical properties of these alloys such as discharge capacity, cycling performance and high rate dischargeability are investigated by battery testing instruments in alkaline electrolyte. The discharge capacity after activation of the Gd6Mn23 alloy is about 520 mAh/g at a discharge current density 50 mA/g. Substitution of small amounts of Ni for Mn in Gd6Mn23−xNix improves the activation, discharge capacity, cycle life, cycle stability and the kinetics of hydrogen absorption–desorption processes at different discharge rates. Most of the Ni substituted alloys were found to possess an exceptional electrochemical performance, while the alloy with x = 0.4 (Gd6Mn22.6Ni0.4) has an exceptional discharge capacity and plateau pressure at discharge current density 200 mA/g and the alloy with x = 1.0 (Gd6Mn22Ni) has an exceptional cycle stability and HRD.