Cyano-Functionalized Polyimide with Li⁺ Coordination Channels: Ultra-Stable Nanofiber Separators for...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Lithium-ion batteries require advanced separators for higher energy density, faster charging, and improved safety.
• Current separators often face limitations in structural stability and ion transport efficiency.

Purpose of the Study:

• To synthesize a novel polyimide separator with enhanced properties for lithium-ion batteries.
• To investigate the impact of cyano groups on separator performance, including wettability, thermal stability, and ion conductivity.

Main Methods:

• Electrospinning of a diamine monomer containing cyano groups to create a polyimide membrane.
• Characterization of the separator's pore structure, porosity, wettability, and thermal stability.
• Assembly and testing of lithium-ion batteries using the developed separator.

Main Results:

• The cyano-based polyimide separator exhibited excellent electrolyte wettability (405%) and thermal stability.
• High ion conductivity (1.04 mS cm⁻¹) and superior rate performance (98.4% capacity retention at 0.5 C after 200 cycles) were achieved.
• Exceptional cycling durability and capacity retention (99.5%, 133.6 mAh g⁻¹) were observed even at 100 °C.

Conclusions:

• Cyano-containing polyimide nanofibrous membranes are promising candidates for high-capacity lithium-ion battery separators.
• The introduction of polar cyano groups significantly enhances separator performance and battery safety.
• This material offers a pathway to next-generation lithium-ion batteries with improved energy density and fast-charging capabilities.