Fig. 6: Sieving by electrodialysis.

a, b Sieving out K⁺ from Li⁺ by electrodialysis. a Permeation of K⁺ and Li⁺ under a bias voltage of 3 V. b Permeation rate of K⁺ and Li⁺ under different bias voltages. Feed solution: 0.1 M K⁺ + 0.1 M Li⁺. The results for 0 V are the results of diffusion dialysis. c, d Sieving out Na⁺ from Li⁺ by electrodialysis. c Permeation of Na⁺ and Li⁺ under a bias voltage of 3 V. d Permeation rate of Na⁺ and Li⁺ under different bias voltages. Feed solution: 0.1 M Na⁺ + 0.1 M Li⁺. a–d shows the high K⁺/Li⁺ and Na⁺/Li⁺ selectivity under electrodialysis. e, f Sieving out Mg²⁺ and Ca²⁺ from Li⁺ by electrodialysis. e Permeation of Mg²⁺, Ca²⁺ and Li⁺ under a bias voltage of 4.5 V when the feed solution contains 0.1 M Mg²⁺ + 0.1 M Ca²⁺ + 0.1 M Li⁺, showing the high Mg²⁺/Li⁺ and Ca²⁺/Li⁺ selectivity. f Permeation rate of Mg²⁺, Ca²⁺ and Li⁺ under different bias voltages. g–i Sieving out competing cations from Li⁺ in salt lake brine. g Permeation of cations under diffusion dialysis. h Permeation of cations under a bias voltage of 4.5 V. i Summarized permeation rate for (g) and (h), showing the potential of our membrane for Li⁺ extraction from salt lake brine using electrodialysis. Error bars in all cases represent standard deviation of the data from at least three individual experiments.