Towards beneficial transformation of aluminum impurity for cathode material regeneration from spent lithium-ion batteries: In-situ Al doping for high-performance LiNi0.9Co0.05Mn0.05O2

Abstract

Aluminum (Al) from current collector is a quite important impurity element affecting the regenerated cathode materials from spent lithium-ion batteries (LIBs). Currently, Al in the leaching solution is difficult to be removed in depth without causing loss of nickel or cobalt. Herein, the quantitative relationship between Al in the leaching solution and regenerated precursors and cathode materials is investigated, and the effects of Al impurity on the macromorphology and microstructure of the materials is revealed. It suggests that Al introduction suppresses the ordered growth of precursors and further leads to disordered grain morphology of regenerated cathode materials, twisting Li+ diffusion pathway. Meanwhile, Al doping could widen LiO6 layer channel, synchronously stabilize layered structure and interfacial properties. Thus, by balancing the effects between morphology and lattice, Al-doped LiNi0.9Co0.05Mn0.05O2 with superior cycling stability (95.1 % capacity retention efficiency after 200 cycles at 1 C) and rate performance (101.8 mAh g−1 discharge capacity at 10 C) is regenerated when Al concentration in the leaching solution is controlled at 1.08 g/L. This study transforms the harmful Al impurity into a beneficial component, and provides a favorable in-situ Al-doping strategy for regenerating high-performance cathode materials from spent LIBs.