RESUMEN
The regeneration of cathode materials would be the highest value-added direction in lithium-ion battery (LIB) recycling research. Li[NixMnyCoz]O2 (NMC) is regenerated from actual industrial scale LIB leachate and purified leachate to investigate the precipitation behavior of impurities, which include potentially toxic elements, such as F, Cl, and S. Regenerated precursors from the actual leachate, purified precursors, and a control sample are synthesized using the hydroxide co-precipitation method. Additionally, simulated precursors from simulated leachate are prepared in order to separate the effects of nonmetallic elements from the effects of metallic elements. The structure and electrochemical properties of the regenerated precursors and the corresponding cathode materials are examined. We first detect the presence of a significant amount of nonmetal elements, such as F as well as well-known metal elements, which include Al, Cu, and Fe, in the regenerated NMC. The concept of yield of precipitation (YOP) is introduced to assess the precipitation behavior of each element during the co-precipitation of the precursors. According to the concentration and YOP in the leachate and the precursors, six metal and three nonmetal elements are categorized. This categorization of impurity elements will certainly provide the LIB recycling industry with a valuable quality control guide.
RESUMEN
As the explosive growth of the electric vehicle market leads to an increase in spent lithium-ion batteries (LIBs), the disposal of LIBs has also made headlines. In this study, we synthesized the cathode active materials Li[Ni1/3Mn1/3Co1/3]O2 (NMC) and Li[Ni1/3Mn1/3Co1/3Fe0.0005Al0.0005]O2 (NMCFA) via hydroxide co-precipitation and calcination processes, which simulate the resynthesis of NMC in leachate containing trace amounts of iron and aluminum from spent LIBs. The effects of iron and aluminum on the physicochemical and electrochemical properties were investigated and compared with NMC. Trace amounts of iron and aluminum do not affect the morphology, the formation of O3-type layered structures, or the redox peak. On the other hand, the rate capability of NMCFA shows high discharge capacities at 7 C (110 mAh g-1) and 10 C (74 mAh g-1), comparable to the values for NMC at 5 C (111 mAh g-1) and 7 C (79 mAh g-1), respectively, due to the widened interslab thickness of NMCFA which facilitates the movement of lithium ions in a 2D channel. Therefore, iron and aluminum, which are usually considered as impurities in the recycling of LIBs, could be used as doping elements for enhancing the electrochemical performance of resynthesized cathode active materials.