Robust Self-Composite Polyimide Separators for Long-Life Lithium-Ion Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Electrospun polyimide (PI) nanofiber separators offer thermal stability for lithium-ion batteries.
• Current limitations include poor mechanical strength and large pores, hindering dendrite suppression.

Purpose of the Study:

• To develop a self-composite polyimide (SCPI) separator to overcome the limitations of traditional PI nanofiber separators.
• To improve mechanical integrity, pore uniformity, and dendrite suppression for high-performance lithium-ion batteries.

Main Methods:

• A "self-composite" strategy integrating electrospinning with non-solvent-induced phase separation (NIPS).
• Fabrication of a hierarchical SCPI separator with an electrospun PI nanofiber scaffold and a NIPS-derived PI matrix.

Main Results:

• The SCPI separator demonstrated a 230% increase in tensile strength and reduced average pore size to 200-500 nm.
• Achieved dendrite-free lithium plating/stripping at 5 mA/cm² and maintained 98.75% capacity after 800 cycles in Li/LFP pouch cells.

Conclusions:

• The SCPI separator effectively homogenizes ion flux, enabling dendrite-free operation and superior battery stability.
• This scalable approach provides a pathway for advanced membrane structures in safe, high-performance lithium batteries.