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 refined to a=8.353(1) Å, b=4.974(1) Å, c=6.194(1) Å and β=114.6(1)° [monoclinic], which is in complete agreement with structural data reported in the literature. Oxidation of graphite present in the positive active material is enhanced at elevated temperatures, and at high anodic potentials. This results in an extremely high carbonate concentration in the active material, as well as in the electrolyte. The high carbonate content, in combination with the relatively high lithium concentration 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 β-Cd(OH)2 and graphite may generate short circuits between the positive and the negative electrodes.