Ion–Dipole Interaction Regulation Enables High-Performance Single-Ion Polymer Conductors for Solid-State Batteries

Solid polymer electrolytes with large ionic conductivity, high ionic transference number, and good interfacial compatibility with electrodes are highly desired for solid-state batteries. However, unwanted polarizations and side reactions occurring in traditional dual-ion polymer conductors hinder their practical applications. Here, single-ion polymer conductors (SIPCs) with exceptional selectivity for Li-ion conduction (Li-ion transference number up to 0.93), high room-temperature ionic conductivity of about 10−4 S cm−1, and a wide electrochemical stability window (>4.5 V, vs Li/Li+) are prepared by precisely regulating the ion–dipole interactions between Li+ and carbonyl/cyano groups. The resulting SIPCs show an excellent electrochemical stability with Li metal during long-term cycling at room temperature and 60 °C. LiFePO4-based solid-state cells containing the SIPCs exhibit good rate and cycling performance in a wide temperature range from −20 to 90 °C. By the same way of ion–dipole interaction regulation, sodium- and potassium-based SIPCs with both high ionic conductivity and high cationic transference numbers are also prepared. The findings in this work provide guidance for the development of high-performance SIPCs and other metal-ion systems beyond Li+.