Preparation of three-dimensional macroporous–mesoporous lithium ion sieve with high Li+ adsorption capacity

Abstract A three-dimensionally macroporous–mesoporous lithium ion sieve (3DM-H 4 Ti 5 O 12 ) was transformed from 3DM-Li 4 Ti 5 O 12 through washing with HCl solution, which was synthesized by a combination of hydrothermal and low-temperature calcination (600 °C) treatment, using polystyrene microarray as hard-template, and titanium isopropoxide and lithium acetate as co-precursors. The influence of HCl concentration and temperature on the deintercalation rate of Li and Ti from Li 4 Ti 5 O 12 was specifically explored to maximize the extraction ratio of Li/Ti. The acceleration of Li extraction and insertion in a porous structure was verified using nonporous Li 4 Ti 5 O 12 as a control. 3DM-H 4 Ti 5 O 12 showed superior Li + adsorption performance (5.51 mmol/g) compared with its nonporous counterpart (1.12 mmol/g), which was ascribed to the reduced Li + mass transfer resistance in the highly interconnected porous channel. The ion selectivity of the 3DM-H 4 Ti 5 O 12 lithium ion sieve followed the order of Li +  > Na +  ~ Ca 2+  > K +  > Mg 2+ . The adsorption performance could be maintained after six cycles. The high adsorption capacity, excellent selectivity, and good recyclability demonstrate the prosperous potential application of 3DM-H 4 Ti 5 O 12 . Graphical Abstract