Highly Stretchable Thermoplastic Polyurethane Separators for Li-Ion Batteries Based on Non-Solvent-Induced Phase...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Flexible and stretchable lithium-ion batteries (LiBs) are crucial for wearable and portable electronics.
• Battery separators must provide Li-ion pathways while preventing short circuits and possess mechanical flexibility.
• Existing separators often lack the required elasticity for highly deformable battery applications.

Purpose of the Study:

• To develop and evaluate a non-modified thermoplastic polyurethane (TPU) separator for flexible LiBs.
• To compare the performance of TPU separators against commercially available polypropylene (PP) separators.
• To assess the mechanical, thermal, and electrochemical stability of TPU separators under stretching conditions.

Main Methods:

• Non-solvent induced phase separation (NIPS) technique was used to fabricate TPU separators.
• Repeated stretch/release tests were conducted to evaluate elasticity and durability.
• Electrolyte wettability, thermal stability, and oxidative stability (via linear sweep voltammetry) were assessed.
• Performance was evaluated in a fabricated coin cell LiB.

Main Results:

• TPU separators demonstrated superior elasticity and elasticity retention compared to PP separators after repeated stretching.
• Excellent thermal stability and electrolyte wettability were observed for the TPU separators.
• TPU separators maintained functional integrity without significant damage after extensive stretching and releasing.
• High oxidative stability, comparable to commercial separators, was confirmed.

Conclusions:

• Non-modified TPU separators fabricated via NIPS are a promising alternative for flexible LiB applications.
• TPU separators offer a robust and elastic solution for energy storage in wearable devices.
• The developed TPU separators exhibit the necessary properties for durable and high-performance flexible batteries.