Work

Reassessing the structure of the sorbent with nominal composition Li1.6Mn1.6O4 used for direct Lithium extraction

Year: 2026

Type: article

Abstract: Lithium-rich manganese spinels have attracted sustained interest because they promise high lithium-ion-sieve capacity. Although the material with nominal composition Li 1.6 Mn 1.6 O 4 presents better performance than those belonging to the Li (1+δ) Mn (2-δ) O 4 series, yet its exact crystal chemistry and structure remains controversial. In the present experimental and theoretical study, the material was synthesized by spray-drying followed by calcination, obtaining the target stoichiometry in which Mn is present with the 4+ oxidation state. Rietveld refinements were performed to synchrotron X-Ray diffraction patterns using Full Prof and FAULTS programs to model stacking-fault-induced reflections broadening. The refinement revealed a two-phase system, formed by ~80 wt% of cubic spinel Li 1.33 Mn 1.67 O 4 and ~ 20 wt% of monoclinic-layered Li 2 MnO 3 , together reproducing the overall Li 1.6 Mn 1.6 O 4 composition. 7 Li solid-state NMR confirmed that lithium occupies 8a and 16d sites in the spinel and the presence of the Li 2 MnO 3 phase. Furthermore, density functional theory calculations revealed that a slight stoichiometric imbalance in the Li/Mn ratio around 1 in Li 1.6 Mn 1.6 O 4 could lead to metastable spinel phases, with Li 2 MnO 3 as main secondary product.

Source: Separation and Purification Technology

DOI: 10.1016/j.seppur.2026.140357