Fig. 2: The effect of N-LTO-PA on Li⁺ and Na⁺ transport selectivity.

A Li⁺ and Na⁺ adsorption on bare LTO and N-LTO activated by HCl. B Li⁺ and Na⁺ ion flux and Li⁺/Na⁺ selectivity obtained by different membranes in ED experiments using a binary (Li⁺, Na⁺) solution. The cross-section TEM images (C), Ion flux and Li⁺/Na⁺ selectivity (D) and the surface SEM images (E) of membranes prepared at different N-LTO loadings. F The ion selectivity in the extractant chamber using different membranes in a binary (Li, Ca) solution. G Li⁺ adsorption capacity of HCl activated LTO nanoparticles (top) and ion flux and selectivity of the N-LTO-PA-0.5 membrane (bottom) at different pHs. H The ionic conductivity of different membranes calculated from the measured membrane resistance and thickness. I Comparison of Li⁺/Na⁺ and Li⁺/Ca²⁺ selectivity (P_Li+/Na+ and P_Li+/Ca2+) of the membrane developed in the current study (red diamond, “This work”) with other CEMs (blue circles, triangles and squares) reported in the literature. Corresponding data can be found in Supplementary Table 9. Each data point representing one published study. Error bars shown in this figure represent the standard deviation from duplicated or triplicated experiments.