Double-Network Polymer Electrolytes with Ionic Liquids for Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Solid-state polymer electrolytes are key for high-energy-density lithium metal batteries (LMBs).
• A major challenge is their low ionic conductivity at room temperature.
• Developing electrolytes with both mechanical strength and high conductivity is crucial.

Purpose of the Study:

• To synthesize and characterize novel composite polymer electrolytes (CPEs) for solid-state LMBs.
• To investigate the influence of different ionic liquids on electrolyte performance.
• To evaluate the electrochemical properties and lithium dendrite suppression capabilities of the CPEs.

Main Methods:

• A facile one-pot method was used to prepare CPEs.
• CPEs incorporated a double-network polymer, ionic liquids (Pyr14TFSI or EmimTFSI), and LiTFSI salt.
• Electrochemical measurements, including ionic conductivity, electrochemical stability, and cycling performance, were conducted.

Main Results:

• The synthesized CPEs exhibited good mechanical properties, thermal stability, and ionic conductivities >10^-4 S cm^-1 at 20 °C.
• CPEs with EmimTFSI showed higher ionic conductivity, while those with Pyr14TFSI offered wider electrochemical stability and better lithium dendrite resistance.
• Li/LiFePO4 batteries using CPE with 34 wt% Pyr14TFSI demonstrated excellent rate capability, cycling stability, and 98.8% coulombic efficiency.

Conclusions:

• Composite polymer electrolytes based on Pyr14TFSI are promising for solid-state lithium metal batteries due to their balanced properties.
• The developed CPEs show potential for practical applications in high-energy-density batteries.
• Further optimization could lead to enhanced battery performance and safety.