Room Temperature to 150°C Lithium Metal Batteries Enabled By a 'Molecular Ionic Composite' Solid Electrolyte

摘要

Molecular ionic composites (MICs) are a new class of solid electrolyte materials developed recently in our group. These materials are constructed from various ionic liquids and a highly charged rigid rodlike polymer, poly(2,2'-disulfonyl-4,4'-benzideneterephthalamide) (PBDT). MICs demonstrate an unprecedented combination of thermal properties (stability up to 300°C), mechanical properties (E' up to ～1 GPa), and ion transport properties (ionic conductivity up to 8 mS/cm). Here we present preparation and characterization of a MIC membrane based on the PBDT polymer, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Pyr_(14)TFSI) and LiTFSI. This MIC membrane is robust and flexible, and exhibits ionic conductivity ～0.2 mS/cm at room temperature. Due to the electrochemical and mechanical stability of the MIC membrane at elevated temperature, Li/MIC/LiFePO_4 coin cells demonstrate excellent cycling performance over a wide temperature range from 20 to 150°C. This study demonstrates that MIC materials represent a promising electrolyte platform for safe and wide-temperature-range lithium batteries.