Preparation of Mg-doped Li1.6Mn1.6O4 with enhanced Li+ adsorption performance and anti-dissolution properties of Mn

Abstract Owing to the increasing global demand for lithium, extraction of lithium from salt lake brine water has received considerable attention. In this study, the magnesium doping to produce Li1.6MgxMn1.6-xO4 (LMMO) was designed to overcome the limitation caused by the loss of Mn due to dissolution. The chemical and morphological properties of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The XRD results confirmed that the crystal structure of Li1.6Mn1.6O4 was retained after Mg-doping. Scanning electron microscopy and energy-dispersive X-ray spectroscopy showed that LMMO has a flake-shaped structure and the Mg2+ ions were uniformly distributed in the precursor. The doping of Mg2+ led to the decrease of Mn3+ content in the precursor, improving its structural stability. The adsorption capacity of LMMO-6% was 35.6 mg g−1, which was greater than that of the undoped sample (33.2 mg g−1). After the tenth cycle, the dissolution loss of Mn in LMMO-6% was 0.55%, and it is smaller than that for lithium manganese oxide (0.94%). Results confirm that the structural stability was improved compared to undoped adsorbents. Moreover, batch adsorption experiments demonstrated the potential of the HMMO-6% adsorbent to be used for lithium adsorption from real salt lake brine.