Polymeric ionic liquid–ionic plastic crystal all-solid-state electrolytes for wide operating temperature range lithium metal batteries

Abstract

In developing all-solid-state polymer electrolytes for wide operating temperature range lithium metal batteries, an exciting organic ionic plastic crystal, N-ethyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (P₁₂FSI), has been introduced into the pyrrolidinium-based polymeric ionic liquid (PIL)/LiTFSI solid system to obtain a novel class of PIL–P₁₂FSI–LiTFSI solid polymer electrolytes (SPEs). Such SPEs reveal flexible mechanical characters, attractive room temperature ionic conductivity above 10⁻⁴ S cm⁻¹, and high thermal and electrochemical stability as well as potential to suppress the lithium dendrite growth. Particularly, Li/LiFePO₄ cells assembled with the as-obtained SPE exhibit high discharge capacity and excellent cycle life over a broad operating temperature range (25–80 °C) and good rate performance. This significant finding indicates that the SPE system obtained in our work has great potential for use in wide operating temperature range lithium metal batteries.