On the growth of Li2CO3 dendrites in nickel-cadmium industrial batteries

A large amount of Li2CO3 dendrites has been detected on positive electrodes in Ni-Cd industrial pocket plate batteries, intended to work in stationary applications, after 3 years in float charge. The lattice parameters were r efined to a = 8.353(1) Angstrom, b = 4.974(1) Angstrom, c = 6.194(1) Angstr om and beta = 114.6(1)degrees [monoclinic], which is in complete agreement with structural data reported in the literature. Oxidation of graphite pres ent in the positive active material is enhanced at elevated temperatures, a nd at high anodic potentials. This results in an extremely high carbonate c oncentration in the active material, as well as in the electrolyte. The hig h carbonate content, in combination with the relatively high lithium concen tration present in both electrolyte and positive electrode, is very likely to be the reason for the formation of the Li2CO3 dendrites. As this process continues, agglomerates of the dendrites in combination with attached beta -Cd(OH)(2) and graphite may generate short circuits between the positive an d the negative electrodes. (C) 1999 Elsevier Science S.A. All rights reserv ed.