Recent progress in hydrogen storage alloys for nickel/metal hydride secondary batteries

This paper reviews the development of hydrogen storage alloys prepared by an effective method of mechanical alloying and milling. It emphasizes alloys based on Mg or that contain Mg due to their low cost, low weight and high hydrogen storage capacity. Hydrogen absorption/desorption and electrochemical measurements are briefly discussed. The electrochemical properties of the alloys that contain Mg are covered in detail, emphasizing the effects of changes in alloy composition. The system of Ti–Ni-based alloys is also introduced. At present, composite hydrogen storage alloys may be the most effective materials for practical application in new nickel/metal hydride secondary batteries. The steps of hydrogen absorption/desorption such as charge-transfer and hydrogen diffusion for evaluating the electrochemical properties of hydrogen storage alloys are discussed. The relationship between alloy composition and electrochemical properties is noted and evaluated.