Metal Hydride Electrodes Applied to Ni‐MH Battery Using Mg‐Y‐Ni‐Cu‐Based Alloys

To improve the electrochemical properties of the Mg‐Ni‐based alloys, mechanical ball milling was used to create the nanocrystalline and amorphous Mg 50− x Y x Ni 45 Cu 5 ( x = 0, 1, 2, 3, 4) + 50 wt%Ni (named Mg 50− x Y x Ni 45 Cu 5 ( x = 0, 1, 2, 3, 4) + 50Ni) alloys. The effects of Y content and ball milling time on the microstructure and electrochemical hydrogen storage properties of the alloy are investigated. The results show that the as‐milled alloys can electrochemical hydrogen absorption and desorption effectively at room temperature. The as‐milled alloys can reach their maximal discharge capability without activation in the initial cycle. The maximum discharge capacities of the 5 h‐ and 30 h‐milled alloys are 407.8 and 600.6 mAh g −1 , respectively. With the increase of Y content, the alloys exhibit a noticeable enhancement in cycle stability. With Y content increasing from 0 to 4, the retention rate of capacity increases from 36% to 63% at 100th cycles for the 5 h‐milled alloy, and the retention rate of capacity increases from 55% to 79% for the 30 h‐milled alloy. Furthermore, Y addition effectively enhances the electrochemical kinetic characteristics of the alloys.