Unique Metal Fog Generation in LiCl-KCl Melt

Abstract

Two types of the so-called “metal fog” were observed during Li electrodeposition in LiCl-KCl eutectic melt. One of them colored gray showed unique behaviors, and was hardly explained by the mechanisms reported before. In this study, the conditions to generate this “gray metal fog” have been investigated in detail, and its mechanism is discussed. A drop of the cathodic current and the subsequent current vibration were observed with the gray fog generation, and the in-situ observation indicated that a black film was formed on the surface of electrode just before this fog dispersion. The black film was formed only on an electrodeposited thin Li metal film, and spread from the edge of the electrode to the whole surface. The black film was formed and disappeared repeatedly, and the gray fog was seen only on the black film. These results suggest that the existence of the black film causes the gray fog generation, and that the film is formed electrochemically and decomposed spontaneously.