Single lithium-ion polymer electrolytes based on poly(ionic liquid)s for lithium-ion batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Developing efficient electrolytes is crucial for advancing lithium-ion battery technology.
• Polymeric ionic liquids (PILs) offer potential as solid-state electrolytes due to their unique properties.
• Achieving high lithium transference numbers is key for improving battery performance.

Purpose of the Study:

• To synthesize a novel lithium-containing room temperature polymeric ionic liquid (PIL) for single lithium-ion conduction.
• To investigate the potential of zwitterionic effects in creating liquid-like lithium salt behavior within a polymer matrix.
• To evaluate the electrochemical performance of the synthesized PIL as an electrolyte.

Main Methods:

• Synthesized a room temperature PIL using zwitterion 3-(1-vinyl-3-imidazolic)propanesulfonate (VIPS) and LiSTFSI.
• Employed in situ photopolymerization with PEGM and PEGDM in propylene carbonate (PC) to form free-standing electrolyte films.
• Characterized the ionic conductivity and lithium transference number of the PIL electrolytes.

Main Results:

• The PIL electrolytes demonstrated excellent lithium transference numbers, approaching unity (0.93 at room temperature).
• Achieved comparable ionic conductivity (σ ≈ 1.31 × 10-4 S cm-1 at 30 °C) with Li+-rich channels.
• Demonstrated promising charge-discharge performance in a Li/LiFePO4 half-cell.

Conclusions:

• The developed zwitterionic PIL is a promising material for single lithium-ion conduction.
• This approach offers a novel model system for designing advanced lithium-ion battery electrolytes.
• The high lithium transference number highlights the potential for enhanced battery safety and efficiency.