Enhanced Lithium Adsorption on an Anion- and Cation-Codoped Lithium Manganese Oxide Ion Sieve with a Thin Fluoride-Protective Coating Layer
Shougui Wang, Yuwen Gao, Fei Gao, Jipeng Dong, Pan Zhang, Guanghui Chen
Abstract
In this work, novel lithium manganese oxide ion sieves (LISs) H 1.6 Mn 1.54 Al 0.02 Cr 0.04 F y O 4– y codoped with Al, Cr, and F ions were synthesized to improve their lithium adsorption performance. The resulting anion- and cation-codoped LISs maintain the spinel structure. Particularly, the introduction of F ions forms a fluoride coating layer on the surface of LISs, playing an important role in stabilizing the LIS structure. Moreover, some Mn 3+ ions are partially replaced by Al 3+ and Cr 3+ ions and some of the surface O 2– ions are replaced by F – ions, forming the stronger Al–O, Cr–O, and metal–fluorine bonds. The synergistic effect of the anion and cation codoping enhances the structural stability of LIS. Compared with undoped and double-doped LISs, the triple-doped LIS H 1.6 Mn 1.54 Al 0.02 Cr 0.04 F 0.1 O 3.9 (HMACFO-10) exhibits a lower manganese dissolution loss, enhanced Li + adsorption performance, and better reusability. In addition, HMACFO-10 affords good adsorption selectivity for Li + ions from brines.