Solvent-free fabrication of pore-filling cation-exchange membranes for highly efficient desalination

The traditional route for ion-exchange membrane fabrication usually involves complex procedures that require substantial quantities of organic solvents and optionally undergo post-modification utilizing strong base or acid. Here, we develop a completely green route for cation-exchange membrane fabrication via a simple soaking pore-filling polymerization method using water as the sole solvent. The resulting pore-filling cation-exchange membranes (PFCEMs) exhibited high ion exchange capacity, moderate water uptake, robust mechanical properties, low area resistance (1.3 Ω cm 2 ) and high limiting current density (181 mA cm −2 ), leading to superior performance for salt desalination. Benefiting from the superior electrochemical properties, PFCEM achieved an ideal desalination rate of 93.4 %, which was comparable to that of the flagship commercial Neosepta CMX membrane (91.5 %). In addition, the low membrane cost and satisfactory long-term stability of the PFCEMs indicated promising features for their scale-up in industrial production and applications.