Advances in the application of ionic liquids in PEO-based lithium-ion solid-state electrolytes: from the perspective of fillers

Abstract

Poly(ethylene oxide) (PEO) composite solid-state electrolytes have been considered promising candidates as electrolytes for all-solid-state lithium batteries with high safety and excellent mechanical properties. However, the ionic conductivity of PEO-based electrolytes is usually low at room temperature, which limits their performances in practical applications. Moreover, their interfacial incompatibility with high-voltage cathode materials remains a challenge despite their better compatibility with lithium-metal anodes. The inevitable problem of lithium dendrite growth also affects the safety performance of these batteries. Ionic liquids (ILs) with high conductivity and ionic mobility are capable of enabling batteries to achieve a higher electrochemical window, offering a new platform for developing more environmentally friendly and sustainable all-solid-state lithium batteries. Considering that there has been a surge in research activities in the field of PEO/ILs systems, this review summarizes the mechanisms of different kinds of ILs in PEO-based solid polymer electrolytes and provides a comprehensive overview of the application of ILs in all-solid-state lithium batteries from the perspective of fillers. Ultimately, this review is expected to guide the design and optimization of novel PEO/ILs systems with enhanced properties for real-world applications.