Recovery of valuable metals from mixed types of spent lithium ion batteries. Part II: Selective extraction of lithium.

Extensive usage of different kinds of lithium ion batteries (LIBs) may result in a huge amount of complicated waste batteries stream, while insufficient attention has been paid on the selective recovery of lithium from these already complicated wastes. Herein, a novel approach was developed for the selective extraction of Li from mixed types of LIBs (LiCoO, LiMnO, LiFePO and LiCoMnNiO) using mild phosphoric acid as efficient leaching agent. It can be concluded from leaching results that 100%, 92.86%, 97.57% and 98.94% Li can be selectively extracted from waste cathode materials of LiCoO, LiMnO, LiFePO and LiCoMnNiO, respectively, while transition metals (Co, Mn, Fe and Ni) can be hardly leached in mild acidic media under optimized leaching conditions. In addition, high selectivity coefficients (β) can be obtained during the extraction of Li from other metals. It can be also discovered from characterization results (SEM, XRD, FT-IR and Raman spectra) that leaching residues are phosphate precipitates, which might be used for the recycling of other metals and preparation of cathode materials. Results from leaching kinetics indicate that the leaching of Li is chemical and internal diffusion controlled reaction, with apparent activation energy (Ea) of 37.74, 21.16, 27.47 and 21.86 kJ/mol for LiCoO, LiMnO, LiFePO and LiCoMnNiO, respectively. Finally, lithium phosphate with a purity of 98.4% can be obtained and the whole process can be efficient candidate for Li recovery with minor environmental impact and little waste produced.