Structure and surface co-modified lithium ion-sieve H_1.6Mn_1.6O₄ sub-micron spheres with efficient enhancement in adsorption of lithium from simulated salt lake brine

Driven by the rapid growth of new energy vehicles and energy storage, development of lithium extraction technologies from salt lake brines has been considerably stimulated. This work introduces a novel method for structure and surface co-modification of the manganese-based lithium ion-sieve H_1.6Mn_1.6O₄ (HMO-EtOH & SDS) sub-micron spheres, employing ethanol (EtOH) and sodium dodecyl sulfate (SDS) as the additives. The HMO-EtOH & SDS sub-micron spheres exhibit a uniform spherical morphology, narrow size distribution (300–600 nm), small average particle size (0.44 µm), large specific surface area (120.06 m²·g⁻¹), super-hydrophilicity and relatively rich porous structure. When utilized as the adsorbents, HMO-EtOH & SDS sub-micron spheres demonstrate a high equilibrium adsorption capacity (q_e = 56.71 mg·g⁻¹) and a fast adsorption rate (t_e = 3.0 h), with a maximum adsorption capacity of 58.74 mg·g⁻¹. After five cycles of adsorption, an excellent cycling performance (retention rate: 80.23 wt.%) and low manganese dissolution rate (below 5.25 wt.%) have been accomplished. Additionally, for extraction of lithium from the simulated salt brine, an equilibrium adsorption capacity of 25.41 mg·g^-1 and relatively high separation coefficients ( ${\alpha }_{\text{Mg}}^{\text{Li}}$= 412.33, ${\alpha }_{\text{Na}}^{\text{Li}}$= 2120.57) have also been achieved.