Preparation of HMn2O4 lithium-ion sieves with low manganese dissolution loss for improved cycling stability

Abstract

Manganese-based lithium-ion sieves have become some of the promising adsorbents for extracting Li⁺ from brines. However, manganese dissolution loss (MDL) severely impairs the stability and cyclicity of ion sieves. A novel ozone eluent was first developed to extract Li⁺ from lithium manganese oxides, which decreased MDL decreased from 5.89% to 0.11%, and after ten regeneration cycles, the adsorption capacity retained 85.39% of the initial value, which was better than 55.15% when only hydrochloric acid (HCl) was used as the eluent. Based on these phenomena, the mechanism for the O₃ lowering of MDL was investigated. First, the catalytic decomposition reaction of O₃ competed with the disproportionation reaction, and the involvement of O₃ inhibited the occurrence of the disproportionation reaction. Additionally, the presence of O₃ and reactive oxygen species provided a preferential electron acceptor compared to Mn³⁺ during the migration of electrons from the bulk phase to the surface. In this study, MDL was greatly reduced with a very simple strategy, and the cycling stability of the adsorbent was improved.