LAUSR

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+.