Eutectic Impetus for Single-Cation Conduction in Unadorned Sulfonated Ionomers

Single-cation conductors based on anionic ionomers are tantalizing for implementing energy-dense batteries yet remain practically limited by poor cation mobility. Hitherto, only the integration of highly charge-delocalized anions with flexible segments through complicated synthesis can access certain conductivity. Herein, via a mild ionomer–(bipolar)ligand eutectic chemistry independent from unipolar plasticizers, we converted readily available sulfonated ionomers that can hardly conduct cations per se into single-cation conductors. The introduced solid bipolar ligands dissociate cation–anion pairs, relying on localized cationic solvation and specialized anionic bonding while not plasticizing the rigid polystyrene backbone. This eutectic interplay enlarges ion-rich phase-separation domains, providing percolating channels for low-barrier cation migration along labile coordination sites, decoupling the ion transport from polymer dynamics. Specifically, with only modest dosages of ligands, the maximum conductivities for simple polystyrenesulfonates containing various cations exceed 10 –5 S cm –1 for Li +, Na +, Zn 2+, and Mg 2+, increased by at least 4 orders of magnitude over virgin ionomers.