Chlorination behavior of Li(Ni1/3Co1/3Mn1/3)O2

The chlorination behavior of Li(Ni1/3Co1/3Mn1/3)O2 (NCM) was investigated as a function of the reaction temperature (400–600 °C) and time (1–8 h) for application in a chlorination-based recycling process. Structural analysis results revealed that chlorination leads to a sequential transition from a hexagonal LiMO2 structure to a hexagonal Li1−x′MO2−y′ (observed only at 400 °C), a hexagonal Li1−xMO2−y (x≥x′, y≥y′, at 400–600 °C), and a spinel-type M3O4 phase (≥500 °C, M represents Ni,Co,Mn). It was also found that this structural transition is accelerated by an increase in the reaction temperature, except at 600 °C, where the thermal decomposition of the Li1−xMO2−y phase inhibited the formation of the M3O4 phase. Weight changes of the samples suggested that the chlorination of the transition metals begins at 500 °C and that its rate increases with an increase in the reaction temperature. It was revealed by a composition analysis that an increase in the reaction temperature (except at 600 °C) and longer times result in a higher Li removal ratio. A temperature of 550 °C was proposed as the optimum temperature for the chlorination of NCM in consideration of the findings from this work.