A Novel Self-Binding Composite Separator Based on Poly(tetrafluoroethylene) Coating for Li-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-performance lithium-ion batteries require advanced separator materials.
• Conventional polyethylene (PE) separators have limitations in thermal stability and ionic conductivity.

Purpose of the Study:

• To develop a novel composite separator for enhanced lithium-ion battery performance.
• To improve ionic conductivity and thermal stability compared to standard PE separators.

Main Methods:

• A composite separator was fabricated using polytetrafluoroethylene (PTFE) coating layers on a commercial PE separator, creating a PTFE/PE/PTFE structure.
• The composite separator underwent treatment with a H₂O₂/H₂SO₄ solution to improve electrolyte affinity.
• Electrochemical performance was evaluated using CR2032 half-cells with LiFePO₄ cathodes and Li anodes.

Main Results:

• The PTFE coating formed a nano-porous structure with excellent electrolyte wettability, significantly boosting ionic conductivity.
• The composite separator demonstrated superior thermal stability compared to the PE separator, comparable to ceramic-coated separators.
• Cells with the composite separator exhibited improved C-rate capability and cycling capacity retention.

Conclusions:

• The developed PTFE/PE/PTFE composite separator offers enhanced ionic conductivity and thermal stability for lithium-ion batteries.
• This composite separator shows potential as a high-performance alternative for advanced rechargeable lithium-ion battery applications.