The extremely low room-temperature ionic conductivity of solid-state polymer electrolytes (SPEs) ranging from 10-7 to 10-5 S cm-1 seriously restricts their practical application in solid-state lithium metal batteries (LMBs). Herein,...

Restricted by the poor ability of polymers to dissociate lithium salts and transport ions, solid‐state polymer electrolytes (SPEs) show extremely low ionic conductivities (≈10−7–10−5 S cm−1) and transference number of lithium ions (tLi+ ≈0.2–0.4) at 25 °C. Here, a novel polymer matrix of SPEs that simultaneously promotes lithium salt dissociation and ion transportation based on a high dielectric poly(vinylidene fluoride‐trifluoroethylene‐chlorotrifluoroethylene) (TerP) and an all‐trans conformational poly(vinylidene fluoride‐trifluoroethylene) (CoP), is developed. The high dielectric constant increases the polarity of CH2CF2 polar groups; then, brings a strong electronegative end that dissociates Li+ from lithium salts. The all‐trans conformation assures all fluorine atoms locate on one side of the chain, constructing ion hopping highways. As a result, the TerP/CoP (TC) SPE exhibits a high ionic conductivity (2.37 × 10−4 S cm−1) and a quite large tLi+ of 0.61 at 25 °C. The Li/TC SPE/Li symmetric cells cycle stably for more than half a year (>4500 h) and the LiNi0.8Co0.1Mn0.1O2/TC SPE/Li cell cycles steadily for 1000 and 600 cycles at 1 C and 2 C at 25 °C, respectively. This work paves a new way to prepare high‐performance SPEs by simultaneously modulating dielectric constants and conformation of polymers.

Conventional way to improve the ionic conductivity of solid-state polymer electrolytes (SPEs) is by incorporating inorganic fillers, although effective, the flexibility of SPEs is damaged more or less. Here we...