Fluorine migration and in-situ doping for regeneration of Ni-rich LiNi0.9Co0.05Mn0.05O2 cathode material from spent lithium-ion batteries

Recycling of spent lithium-ion batteries (LIBs) has raised wide concerns vis-à-vis resource value and environmental protection. Benefiting from the short process and high added value of the recycled products, the regeneration of cathode materials from spent LIBs is a popular approach. However, due to the lack of studies on fluorine (F) migration and the impact thereof on recycled materials, F control relies on deep removal and becomes a considerable challenge, limiting the generation of high-quality cathode materials. Herein, the migration-transformation behaviors of F are investigated in the integrated pyrolysis-leaching-regeneration process of spent LIBs. It is indicated that 45.71% of the amount of F is released into the atmosphere during pyrolysis and some amount of F in the leaching solution is adsorbed into coprecipitated precursors through coordination with metal ions and then regularly entering the lattices of the regenerated LiNi0.9Co0.05Mn0.05O2. Regarding the effects of F on the regenerated LiNi0.9Co0.05Mn0.05O2, a moderate F concentration (approximately 0.30 g L−1) in the leaching solution can boost the regenerated LiNi0.9Co0.05Mn0.05O2 material’s cycling stability (the capacity retention of 95.7% after 100 cycles at 1 C), due to the stabilizing effect of F-doping on the regenerated material’s structure. This study reveals the migration-transformation mechanisms of F during the recycling of spent LIB and provides a rational in-situ F-doping strategy for the regeneration of LiNi0.9Co0.05Mn0.05O2.