Supramolecular pseudo-nanophase separation enables ion transport parity with conventional membranes

Supramolecular-engineered pseudo-nanophase separation offers a compelling strategy for fabricating ion-conducting membranes with industrial scalability while maintaining rapid ion transport and chemical robustness. However, fundamental distinctions between pseudo-nanophase separation and its conventional counterpart remain poorly understood. We engineered ion-conducting membranes featuring snowflake-like multi-branched hydrophilic sidechains through covalent and supramolecular grafting, inducing conventional versus pseudo-nanophase separation. Comparative analysis revealed both architectures form analogous 4–11 nm hydrophilic domains (∼7 nm median) through hydrophobic/hydrophilic segregation. Though conventional domains contain tethered sidechains versus sulfuric acid solutions in pseudo-separated counterparts, the membranes demonstrate comparable area resistances (0.25 vs 0.24 Ω cm²) and vanadium permeabilities (1.1 vs 1.3 $\times$ 10⁻⁹ m² s⁻¹), leading to indistinguishable efficiencies and cycling stability in vanadium redox flow batteries. The observed functional equivalence, wherein proton transfer kinetics and vanadium-ion exclusion are largely insensitive to the molecular constitution of the engineered nanochannels, challenges conventional membrane design paradigms emphasizing covalent architectures for optimal ion selectivity. This finding advances the mechanistic understanding of nanochannel-mediated ion transport and substantiates the high credibility and efficiency of the pseudo-nanophase separation strategy.