Preparation of nickel and graphene modified La9CeMg80Ni5 composites and their microstructure and electrochemical properties

Abstract

A La2Mg17-type alloy La9CeMg80Ni5 was prepared and mechanically crushed to powders. Ni and Graphite (GR) were added during ball milling to prepare the surface-modified La9CeMg80Ni5-GR-Ni composites. The influence of milling time and Ni content on the structure and electrochemical properties of the composite materials were investigated. After milling, the composite materials are capable of electrochemically hydriding and dehydriding at room temperature. As Ni content increases, the 40 h-milled composites show an increased discharge capacity from 219.6 to 986.2 mAh/g, HRD from 75.3% to 86.8%, and capacity retention rate of 20th cycle from 58.2% to 65.8%; the 80 h-milled composites show an increased discharge capacity from 252.6 to 1034.7 mAh/g, HRD from 80.5% to 87.9%, and capacity retention rate of 20th cycle from 47.3% to 56.2%.