Annealed SiO 2 Protective Layer on LiMn 2 O 4 for Enhanced Li-Ion Extraction from Brine.

In this study, we present a novel approach for selective Li-ion extraction from brine using an LiMnO ion sieve coated with a dense silica layer, denoted as LMO@SiO. The SiO layer is controllably coated onto the LMO surface, forming passivation layers and ion permeation filters. This design effectively minimizes the acidic corrosion of the LMO and enhances the Li adsorption capacity. Additionally, the SiO layer undergoes calcination at various temperatures (ranging from 300 to 700 °C) to achieve different compactness levels of the coating layer, providing further protection to the LMO crystal structures. As a result of these improvements, the optimized LMO@SiO adsorbent demonstrates an exceptional Li adsorption capacity of 18.5 mg/g for brine, and even after seven adsorption-elution cycles, it maintains a capacity of 15.3 mg/g. This outstanding performance makes our material a promising candidate for efficient Li extraction from brine or other low-concentration Li solutions in future applications.