Microencapsulation of Mg‐Ni hydrogen storage alloy

Abstract

Metal-hydrogen systems are currently used in a heat storage and other applications; however, some difficulties still exist in the actual process. It is well-known that hydrogen storage alloys, particularly powders, have very poor thermal conductivity and disintegrate into a very fine powder easily with the repeated cycling of hydrogen charging and discharging. Ishikawa et al. (1985) proposed a copper microencapsulation method for hydrogen storage alloy. With this method, powder was coated in a thin layer of copper by a plating technique. They showed that the compacts obtained by this method have enough strength without the loss of storage capacity, although they have been compressed at room temperature. However, data on both thermal property and kinetics of the Cu-micro-encapsulated hydrogen storage alloy is needed for predicting temperature distribution in the heat storage unit where simultaneous hydrogen and heat transfer occurs. In this article, an experimental study of thermal conductivity, diffusivity and dehydrating rate of Mg-Ni hydrogen storage alloy is described, in which a main attempt was made to assess the effect of Cu-encapsulation on them.