Phase structures and electrochemical properties of La–Mg–Ni-based hydrogen storage alloys with superlattice structure

Abstract

La–Mg–Ni-based alloys with unique superlattice structures emerged as one of the most promising negative electrode materials for Ni/MH batteries because of their high discharge capacity, energy density and rate capability. They usually contain multiphase structures, and the phase composition plays a significant role in determining their electrochemical performance. This review aims to summarize the latest progresses in studying the phase composition and electrochemical properties of La–Mg–Ni-based alloys, thus to provide guidance for further studies, design and optimization of related negative electrode materials for Ni/MH power batteries. The review starts with the structural characteristics of the superlattice alloy phases in La–Mg–Ni-based alloys. Subsequent emphases are placed on the variations in phase composition of La–Mg–Ni-based alloys induced by different heat treatment procedures and elemental compositions, followed by the next two parts in which the electrochemical characteristics of AB3-, A2B7- and A5B19-type single-phase alloys are summarized, and the effects of phase composition and microstructure on the electrochemical properties are illustrated. Finally, perspectives and challenges in regard of the rational design and electrochemical improvement of La–Mg–Ni-based alloys as high-performance negative electrode materials for Ni/MH batteries are discussed.