Electrochemical incorporation of lithium into palladium from aprotic electrolytes

Abstract

Among numerous questions raised by the recent paper of Fleischmann et al. [l], describing their heavy water electrolysis experiments, an important one concerns the specific influence of the cation of LiOD electrolyte on the behaviour of a palladium cathode. In fact. the reported observations of an excess heat generation in the latter experiments seem to be closely associated with the presence of Li+ cations in the electrolyte [2]. One of the typical features of the prolonged electrolyses of a 0.1 M LiOD + D20 solution between palladium cathodes and platinum anodes. mentioned by Fleischmann et al. [l], was the build-up of high cathodic overvoltages. This leads to an important question: what is the critical value of the electrode potential which would allow the incorporation of lithium into the PdD, cathode [3]? Lithium has been shown to alloy electrochemically, at ambient temperature. with a number of metals including the three noble metals. gold. silver and platinum [4]. In these electrolysis experiments, performed in a 1 M LiClO, + propylene carbonate solution, the formation of lithium alloys at Au, Ag and Pt cathodes was observed to start at potentials slightly more positive than ca. 0.4 V with respect to the Li+/Li electrode. The aim of the present study was to establish in which potential range the Lit cations undergo reduction at a palladium cathode and whether such a reaction is