Lamellar confined ionic liquid electrolytes with advanced performance for Li-ion batteries

Abstract

Ionic liquids are promising to rival traditional organic solvent to develop safe electrolytes for Li-ion batteries. However, the ionic liquid-based electrolytes still suffered from issues of inferior performance and potential leakage. Here, non-ionic surfactant Brij58 was introduced into ionic liquid electrolytes (BMPTFSI/LiTFSI) consisting of 1-butyl-1-methylpyrrolidinium bistriflimide (BMPTFSI) and LiTFSI salt to construct solid-state lyotropic liquid crystals (LLCs). Self-assembly of Brij58 in ionic liquid electrolytes constructed lamellar nanostructures, which confined the ionic liquid electrolytes to form layered conducting channels. The nanoscale layered conducting channels in solid-state LLC electrolytes endowed liquid-like ion conductivity and significantly improved Li-ion transfer. Although the LLC electrolytes only consumed 50 wt % BMPTFSI/LiTFSI, the discharge capacities and rate performance of the Li-ion batteries based on LLC electrolytes was much improved comparing to that containing pristine BMPTFSI/LiTFSI. Also, the flame-retardant feature retained within the lamellar LLC electrolytes. The work paved new way for optimizing the conducting performance of IL electrolytes by constructing lamellar lyotropic LLC nanostructures.