Abstract
Lithium aluminum oxide has previously been identified to be a suitable compound to recover lithium (Li) from Li-ion battery recycling slags. Its formation is hampered in the presence of high concentrations of manganese (9 wt.% MnO2). In this study, mock-up slags of the system Li2O-CaO-SiO2-Al2O3-MgO-MnOx with up to 17 mol% MnO2-content were prepared. The manganese (Mn)-bearing phases were characterized with inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), electron probe microanalysis (EPMA), and X-ray absorption near edge structure analysis (XANES). The XRD results confirm the decrease of LiAlO2 phases from Mn-poor slags (7 mol% MnO2) to Mn-rich slags (17 mol% MnO2). The Mn-rich grains are predominantly present as idiomorphic and relatively large (>50 µm) crystals. XRD, EPMA and XANES suggest that manganese is present in the form of a spinel solid solution. The absence of light elements besides Li and O allowed to estimate the Li content in the Mn-rich grain, and to determine a generic stoichiometry of the spinel solid solution, i.e., (Li(2x)Mn2+(1−x))1+x(Al(2−z),Mn3+z)O4. The coefficients x and z were determined at several locations of the grain. It is shown that the aluminum concentration decreases, while the manganese concentration increases from the start (x: 0.27; z: 0.54) to the end (x: 0.34; z: 1.55) of the crystallization.
Highlights
The chemicals used for producing the mock-up slags are lithium carbonate
The suppression of the formation of LiAlO2 engineered artificial minerals (EnAM) in mock-up slag (MUS) with increasing Mn content was studied by powder X-ray diffraction (PXRD)
It was evaluated by studying the Mn species using X-ray absorption near edge structure (XANES)
Summary
Modern technologies, such as renewable energy and e-mobility, demand a new portfolio of technology-critical elements and materials. The following section gives a short introduction to the relevant binary subsystems of the Al2 O3 -MnOx -Li2 O ternary system, which itself is not yet published. This will allow putting the presented results into the mineralogical context. Paulsen and Dahn [7] created a binary phase diagram of Li-Mn-O in air. They described a spinel with the formula Li(1+x) Mn(2−x) O4 to be stable between 400 and 880 ◦ C. 400 ◦ C, the only stable spinel phases are Li4 Mn5 O12 and LiMn1.75 O4
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
