Coordination Environment Engineering of Titanium Spinel for Enhanced Lithium Recovery

Salt lake lithium extraction accounts for 35% of global Li2CO3 production, but current adsorbents are limited by single coordination environments. Here, we engineer the coordination environment of titanium spinel (H4–xLixTi5O12, HTO) by selectively exposing (110) and (111) crystal facets to modulate the tetrahedral and octahedral Li+ sites. The (111) facet exhibits high adsorption capacity (41.34 mg/g), while the (110) facet offers rapid kinetics (equilibrium in 10 min). Density functional theory (DFT) calculations, Raman spectroscopy, and 6/7Li solid-state NMR (ssNMR) spectroscopy reveal that tetrahedral sites lower dehydration energy and enhance mobility, while octahedral sites enable deeper diffusion and higher capacity. Coordination modulation thus enables a synergistic improvement in Li+ adsorption performance. This work highlights facet engineering as a strategy to enhance ion recovery and guide next-generation adsorbent design.