A hydrophilic CeO2 coating enabling enhanced structural stability and lithium recovery of the Li1.6Mn1.6O4 lithium ion sieve

Lithium ion sieve Li 1.6 Mn 1.6 O 4 (LMO) is a promising adsorbent for lithium extraction from liquid resources due to its high Li + selectivity and theoretical adsorption capacity. However, its practical application is limited by poor structural stability and the decrease of adsorption capacity resulting from gradual Mn dissolution loss during acidic regeneration process. Herein, a surface modification strategy was proposed to construct a continuous and dense CeO 2 coating on LMO surface, effectively addressing the critical challenge of structural instability and simultaneously improving adsorption performance. This protective layer suppressed Mn leaching, reducing the leaching rate to 3.33% in the first cycle compared with 4.57% for pristine LMO, and further to below 3% after ten consecutive adsorption-desorption cycles, effectively enhancing the structural stability. Furthermore, the excellent hydrophilicity of the CeO 2 coating could enhance the effective contact between the Li + ions in solution and the adsorbent, promoting the migration of Li + and its exchange with protons. As a result, the lithium uptake of optimized CeO 2 -coated LMO composite (CeO 2 @LMO) was 32.55 mg·g −1 much higher than 27.92 mg·g −1 in bare LMO, while retaining 85.50% of its initial capacity after ten cycles. Simulation results further revealed that CeO 2 @LMO exhibited a lower adsorption energy ( E ad ) and a reduced Li + diffusion energy barrier compared with LMO, facilitating Li + migration from the aqueous phase to the solid-liquid interface and accelerating its diffusion within the adsorbent. This work demonstrates that a single surface modification can simultaneously overcome LMO's key limitations, offering a viable strategy for developing durable and efficient lithium recovery systems.