Common ion effect is a phenomenon in chemistry that describes the decrease in solubility of a compound when it is dissolved in a solution that already contains one of its constituent ions. This effect occurs due to the principle of chemical equilibrium and Le Chatelier's principle. This page discusses lithium carbonate's role in lithium batteries, produced through a reaction with carbon dioxide. It explains the common ion effect , where adding a common ion decreases a compound's … The common ion effect states that the ionisation of a weak electrolyte is suppressed in presence of a strong electrolyte containing an ion common to the weak electrolyte.