The correlation between composition and electrochemical properties of metal hydride electrodes

This paper is concerned with an overview of the properties of metal hydride electrodes used for battery applications. The emphasis is on the propertie s of AB(5) electrodes but others are treated as well. The review begins wit h a brief discussion of the pertinent chemistry of hydrogen in metals, the properties of intermetallic hydrides and their relation to electrochemical behavior. Systematic guidelines which permit the modification of such prope rties for electrochemical applications are discussed. The electrochemical b ehaviors of certain specific AB(5) alloy electrodes are covered in detail, emphasizing the effects of composition changes with respect to both the A a nd the B components. The consequences of electrode expansion and contractio n with respect to hydride formation and decomposition are discussed quantit atively. Novel alloy compositions and phases are noted and evaluated. The a ttractive properties of cobalt-free, non-stoichiometric AB(5+x) electrodes are noted. (C) 1999 Elsevier Science S.A. All rights reserved.