Sandwich-Structured PI-FPU/Celgard/PI-FPU Separator for Long-Life Room-Temperature Sodium-Sulfur Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Room-temperature sodium-sulfur (RT Na-S) batteries face challenges with polysulfide shuttle and dendrite growth, limiting their stability and safety.
• Developing robust separators is crucial for overcoming these limitations in RT Na-S battery technology.

Purpose of the Study:

• To design and fabricate a novel sandwich structure separator for RT Na-S batteries.
• To investigate the effectiveness of the PI-FPU/Celgard/PI-FPU separator in suppressing polysulfide shuttling and dendrite penetration.
• To evaluate the electrochemical performance and safety enhancements offered by the new separator.

Main Methods:

• Electrospinning of a fluorinated polyurethane copolymerized polyimide (PI-FPU) fiber membrane.
• Assembly of a sandwich structure separator (PI-FPU/Celgard/PI-FPU) using commercial Celgard.
• Testing of sodium-symmetric cells and RT Na-S batteries with the developed separator.

Main Results:

• The PI-FPU/Celgard/PI-FPU separator effectively suppressed polysulfide shuttle via physical and chemical confinement.
• The robust structure inhibited dendrite penetration and improved thermal stability, enhancing safety.
• Sodium-symmetric cells achieved stable cycling over 1000 hours; RT Na-S batteries maintained 555 mAh g⁻¹ after 1500 cycles at 3 A g⁻¹.

Conclusions:

• The developed sandwich separator offers a feasible strategy for creating high-safety and long-life RT Na-S batteries.
• The combination of PI-FPU and Celgard provides synergistic effects for improved battery performance.
• This approach paves the way for practical applications of advanced RT Na-S battery technology.