Advanced Poly (Ether Ether Ketone) Separator for Lithium Metal Battery.

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• High-energy lithium metal batteries (LMBs) require advanced separators for improved safety and performance.
• Poly(ether ether ketone) (PEEK) offers excellent chemical resistance and thermal stability but is challenging to process into effective separators.

Purpose of the Study:

• To develop a novel, heat-resistant PEEK separator with a hierarchical pore architecture for high-energy-density LMBs.
• To overcome the processing challenges associated with conventional PEEK separator fabrication.

Main Methods:

• A reversible chemical modification strategy was employed to create PEEK separators.
• The fabricated separators feature a unique hierarchical pore structure: dense surface layers, horizontally aligned pores in middle layers, and honeycomb-structured bottom layers.

Main Results:

• The PEEK separators demonstrated fast ion transport and uniform Li+ flux, enabling dendrite-free lithium deposition.
• A LiFePO4||Li battery using the PEEK separator achieved 103.6 mAh·g-1 after 1000 cycles at 3 C, showing over double the cycle life of other PEEK separators.
• High capacity retention (84.2% after 200 cycles at 70 °C) confirmed battery safety in high-temperature environments.

Conclusions:

• The developed PEEK separators represent a significant advancement in separator manufacturing for high-safety LMBs.
• The reversible chemical modification strategy offers a new approach for fabricating functional separators with sophisticated pore architectures.