Cu-Mn electronic coupling stabilizes spinel manganese ion sieves for selective lithium recovery

Cu-Mn electronic coupling stabilizes spinel manganese ion sieves. • Cu doping reduces first-cycle Mn dissolution from 3.33% to 0.21%. • Cu-HMO retains 96.8% of lithium uptake after ten regeneration cycles. • Cu substitution raises Mn-vacancy formation energy by 0.403 eV. • Cu doping strengthens lithium binding from −3.515 to −4.556 eV. Manganese-based lithium ion sieves suffer from Mn dissolution and structural degradation during acid regeneration. Herein, Cu-doped HMO (Cu-HMO) was developed to simultaneously enhance Li + adsorption and structural stability. Cu incorporation preserved the spinel Mn O framework while increasing the specific surface area and regulating the Mn valence distribution. XPS revealed decreased Mn 3+ and increased Mn 4+ fractions accompanied by low-valence Cu species, indicating Cu Mn electronic coupling that suppresses Jahn-Teller distortion and Mn 3+ disproportionation. Cu-HMO exhibited a maximum Li + adsorption capacity of 49.15 mg/g at 298 K and maintained superior performance in the presence of various competing ions. During ten adsorption-desorption cycles, Cu-HMO exhibited improved capacity retention and markedly reduced Mn dissolution, with the first-cycle Mn dissolution rate decreasing from 3.33% for HMO to only 0.21% for Cu-HMO, corresponding to a reduction of approximately 94%. Density functional theory (DFT) calculations showed that Cu substitution increased the Mn-vacancy formation energy by 0.403 eV and strengthened Li adsorption from −3.515 to −4.556 eV. These results demonstrate that Cu-induced electronic regulation provides an effective strategy for constructing stable and selective manganese ion sieves. Download: Download high-res image (208KB) Download: Download full-size image