Self-intercepting interference of hydrogen-bond induced flexible hybrid film to facilitate lithium extraction

Supported lithium-ion sieve (LIS) adsorbents have received widespread attention due to their excellent inherent adsorption potential toward lithium (Li) in the liquid Li source. However, LIS-based adsorbents still suffer from slow Li extraction rate and reduced Li selectivity caused by the embedding of the active sites and the adverse effects of high level of competing ions from the seawater/brine. Here, relying on the hydrogen bond (O[sbnd]Mn[sbnd]O···H[sbnd]O) interaction, a LIS-based sandwich heterostructure is designed by the confinement of 0D MnO₂·0.3H₂O (HMO) nanoparticles into the interlayer of a flexible 2D MXene/1D cellulose nanofiber (MC) hybrid film (HMO@MC). Benefiting from the strong hydrogen bond interaction, the HMO@MC hybrid film achieves an excellent LIS utilization (up to 96 %) and a maximum Li adsorption capacity of 21.39 mg g⁻¹, outperforming most LIS-based adsorbents. More impressively, the HMO@MC heavily reduces the Li migration barrier by self-intercepting interference through the steric hindrance effect of surface functional groups, thereby obtaining a fast Li adsorption rate (18.23 mg g⁻¹ HMO, 12 h) and a super-high Li selectivity (e.g., Li/Na of 29231.8 and Li/Mg of 3605.9). This work offers a new adsorbent designing idea for Li extraction from liquid lithium source and will inspire more efforts in constructing LIS-based adsorbents for Li recovery.