Quaternary Polymer Electrolytes Containing an Ionic Liquid and a Ceramic Filler

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Poly(ethylene oxide) (PEO) is a promising polymer electrolyte for solid-state batteries.
• Enhancing the thermal and electrochemical properties of PEO is crucial for practical applications.
• Ionic liquids and ceramic fillers are potential additives to improve PEO-based electrolytes.

Purpose of the Study:

• To investigate the individual and combined effects of an ionic liquid (1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide) and a ceramic filler (silicon dioxide) on PEO electrolytes.
• To evaluate the impact of these additives on the thermal and electrochemical properties of the electrolytes.
• To assess the long-term cycling performance of the optimized solid polymer electrolyte in lithium-ion batteries.

Main Methods:

• Synthesis and characterization of poly(ethylene oxide) electrolytes with varying concentrations of ionic liquid and silicon dioxide.
• Differential scanning calorimetry (DSC) to determine glass transition and melting temperatures.
• Electrochemical impedance spectroscopy (EIS) to measure ionic conductivity.
• Cyclic voltammetry and galvanostatic cycling to evaluate battery performance in Li/LiFePO4 cells.

Main Results:

• The electrolyte containing both 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide and silicon dioxide exhibited the lowest glass transition temperature (-60 °C) and melting temperature (27 °C).
• This composite electrolyte demonstrated the highest ionic conductivity across all investigated temperatures.
• The highest limiting current density (at 40 °C) and the best long-term cycling stability in Li/LiFePO4 cells were achieved with the dual-component electrolyte.

Conclusions:

• The combination of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide and silicon dioxide synergistically enhances the thermal and electrochemical properties of poly(ethylene oxide) electrolytes.
• This optimized solid polymer electrolyte shows significant potential for improving the performance and safety of lithium-ion batteries.
• The findings suggest a viable strategy for developing advanced solid-state battery electrolytes.