Tailoring Nb5+ doping in manganese oxides to enhance the adsorption performance and structural stability of spinel-type manganese-based lithium ion-sieve

In recent years, the technology for rapid extraction of lithium from salt-lake brines has attracted extensive attention. Spinel-structured lithium manganese oxide has been reported to be a promising adsorbent owing to its large lithium adsorption capacity and excellent selectivity. However, its application is limited by manganese dissolution. In this study, NbCl 5 was used as a dopant to prepare high-valence Nb 5+ -doped H 1.6 Mn 1.6 O 1.6 lithium-ion sieves (Nb-doped lithium-ion sieve) hydrothermal and solid-state methods. The results have shown that Nb 5+ doping could significantly increase the average manganese oxidation state, suppress Jahn-Teller distortion and enhance structural stability by Nb–O bonding. Meanwhile, density functional theory (DFT) simulation also demonstrated the enhanced stability caused by Nb doping. The Nb doped lithium-ion sieves presented an excellent Li + selectivity in brine from West Tai Kinel Salt Lake. After 10 cycles of adsorption–desorption, the adsorbent achieved a capacity of 29.15 mg/g, and the capacity retention rate was over 80%, while the manganese loss was only 4.0%, which was significantly better than that of the corresponding adsorbent without modification. This work provides a simple strategy to prepare stable and high-performance manganese-based lithium-ion sieves.