Lyotropic Lamellar Nanostructures Enabled High-Voltage Windows, Efficient Charge Transport, and Thermally Safe Solid-State Electrolytes for Lithium-Ion Batteries.

Abstract

Developing electrolytes combining solid-like instinct stability and liquid-like conducting performance will be satisfactory for efficient and durable Li-ion batteries. Herein lamellar lyotropic liquid crystals (LLCs) demonstrate high-voltage windows, efficient charge transport, and inherent thermal safety as solid-state electrolytes in lithium-ion batteries. Lamellar LLCs are simply prepared by nanosegregation of [C16Mim][BF4] and LiBF4/Propylene carbonate (PC) liquid solutions, which induce lamellar assembly of the liquids as dynamic conducting pathways. Broadened liquid conducting pathways will boost the conducting performance of the LLC electrolytes. The lyotropic lamellar nanostructures enable liquid-like ion conductivity of the LLC electrolytes at ambient temperatures, as well as provide solid-like stability for the electrolytes to resist high voltage and flammability overwhelming to LiBF4/PC liquid electrolytes. Despite minor consumption of PC solvents (34.5wt.%), the lamellar electrolytes show energy conversion efficiency comparable to the liquid electrolytes (PC wt. 92.8%) in Li/LiFePO4 batteries under ambient temperatures even at a 2C current density, and exhibit attractively robust stability after 200th cyclic charge/discharge even under 60°C. The work demonstrates LLC electrolytes have great potential to supersede traditional liquid electrolytes for efficient and durable Lithium-ion (Li-ion) batteries.