Fig. 3: Selective separation of monovalent cations from concentrated LIB leaching solutions.

a Schematic representation of the selective electrodialysis system and mechanisms governing metal ion selectivity, including size exclusion, electrostatic repulsion, and chemical affinity; b Color evolution of the leaching solution during separation: from dark brown (initial solution) transitions to dark red (Mn²⁺, Ni²⁺, and Co²⁺-rich solution) and colorless (Li⁺ and Na⁺-rich solution); c First-stage selective electrodialysis separation of 4 L leaching solution, showing changes in metal ion concentrations (Li⁺, Na⁺, Mn²⁺, Ni²⁺, and Co²⁺) across feed, transitional-1, transitional-2, and recovery chambers under the current density of 1.0 mA cm⁻²; d Second-stage selective electrodialysis separation of 2 L transitional solution, tracking concentration changes in feed, transitional and recovery chambers; e Separation efficiency: the cumulative recovery rates of monovalent cations (Li⁺: 96.5%, Na⁺: 96.4%) and rejection rates of multivalent cations (Mn²⁺, Ni²⁺, and Co²⁺: 100%); f The energy, economic, and environmental analysis of energy consumption, energy cost, and investment cost for Li⁺ recovery; g Optimized selective membrane dual-stage distillation performance metrics, including recovery rate (96.5%), purity (100%), and associated energy, economic and environmental costs under current density of first stage at 1 mA cm⁻² and second-stage at 0.5 mA cm⁻². R_m monovalent metal ion recovery rate. P_Li purity of recovered Li⁺. C_i investment cost. C_Li Li⁺ recovery cost. C_e energy cost. EC energy consumption. Error bars denote the standard deviation of the means (n = 2). Source data are provided as a Source data file.