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+ .
Keywords: Li-ion transference numbers; ion-dipole interaction regulation; single-ion conductors; solid polymer electrolytes; solid-state batteries.
© 2022 Wiley-VCH GmbH.