A novel giniite route to separate impure Fe/Al for recovering Li from spent lithium-ion battery

Abstract

Spent Li–ion batteries are valuable to be disassembled as metals, plastics, and Li-rich black powder. Unlike metals and plastics, Li-rich black powder contains abundant impurities of Fe/Al/P, and its recycling is challenging to date. Herein, a facile hydrothermal route was developed to recycle the black powder as giniite spheres and griceite cubes. Results showed that the black powder comprised 28.2% Fe, 3.1% Al, 4.8% Li, and 19.7% P and was dissolved by diluted azotic acid to produce an Fe/Al/Li/P-rich leachate. Fe/Al/Li removal was achieved by 99.7%, 96.3%, and 23.2% by adjusting the leachate to pH 3. By contrast, with hydrothermal treatment, 99.3% Fe and 51% Al were removed as giniite spheres with diameters of 4–8 μm, while the loss of Li was less than 1%. With the addition of glucose, the Fe/Al removal efficiencies were further increased to 99.9% and 98.8%, and the loss of Li was only 1.9%. With the hydrothermal treatment, Fe/Al reacted with phosphate to form giniite spheres, in which free H+ was generated and accumulated in the leachate to steadily retard Fe/Al removal. However, in the presence of glucose, it reacted with nitrate to consume the generated H+ and then continued Fe/Al removal, which resulted in the low concentrations of the remaining Fe/Al in the leachate. After Fe/Al removal, the rest of the Li was easily precipitated as cubic griceite. Thus, this method is a promising strategy to effectively recycle Li from spent Li batteries.