Photo-Crosslinked Polyurethane-Containing Gel Polymer Electrolytes via Free-Radical Polymerization Method

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Developing advanced electrolytes is crucial for improving lithium-ion battery performance and safety.
• Current electrolytes face challenges with stability, ionic conductivity, and electrolyte leakage.
• Gel polymer electrolytes (GPEs) offer a promising alternative for safer and more efficient energy storage.

Purpose of the Study:

• To synthesize novel crosslinked gel polymer electrolytes (GPEs) for lithium-ion battery applications.
• To investigate the structural, electrochemical, and thermal properties of the developed GPEs.
• To evaluate the performance of GPEs in a lithium-ion coin cell.

Main Methods:

• Fabrication of crosslinked GPEs using polyurethane acrylate (PUA), polyurethane methacrylate (PUMA), vinyl phosphonic acid (VPA), and bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) via UV-initiated free-radical polymerization.
• Characterization of ionic conductivity, electrochemical stability, and mechanical/thermal properties.
• Assembly and testing of LiFePO4 cathode-based coin cells using the developed GPEs.

Main Results:

• The novel crosslinked GPE exhibited significantly higher ionic conductivity (1.83 × 10^-3 S cm^-1) compared to commercial separators.
• The GPE demonstrated excellent mechanical and thermal stability, with reduced electrolyte leakage and improved liquid retention.
• Coin cells showed high reversible capacity (149 mA h g^-1 at 0.1 C), near 100% Coulombic efficiency, and retained 91.5% of capacity after cycling.
• Electrochemical stability was observed up to 3.78 V.

Conclusions:

• The developed crosslinked GPEs offer superior ionic conductivity, enhanced stability, and improved safety features for lithium-ion batteries.
• The unique crosslinked structure effectively manages electrolyte retention and reduces leakage.
• These GPEs show great potential for the development of high-performance and safe flexible energy storage systems.