DOPO-polyimide/PAN hybrid matrices for mechanically robust and flame-retardant high-voltage separators

Titelangaben

Badri, Rahul ; Hiwase, Shweta ; Agarwal, Seema ; Banerjee, Susanta:
DOPO-polyimide/PAN hybrid matrices for mechanically robust and flame-retardant high-voltage separators.
In: Materials Chemistry Frontiers. (2026) .
ISSN 2052-1537
DOI: https://doi.org/10.1039/d6qm00489j

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Abstract

This study reports the rational design and fabrication of a polyacrylonitrile (PAN)-impregnated, 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO)-based polyimide hybrid separator for advanced lithium–metal battery (LMB) applications. The optimised PI(5 wt%)_ES-PAN membrane exhibits exceptional thermal, mechanical, and dimensional stability. The incorporation of the DOPO moiety imparts intrinsic flame retardancy by generating and releasing radical-scavenging phosphorus monoxide and phosphorus dioxide active species in situ. Furthermore, the tailored pore architecture and polymer chemistry yield superior electrolyte uptake, porosity, and interfacial wettability. Upon immersion in a 1 M LiPF6/EC: DMC liquid electrolyte, the separator exhibits ionic conductivities of 0.16 × 10−4 S cm−1 and 0.42 × 10−4 S cm−1 at 30 °C and 70 °C, along with a wide electrochemical stability window of 4.5 V against lithium metal and a favourable lithium transference number of 0.2. Overall, the designed PI(5 wt%)_ES-PAN separator highlights a robust materials design strategy for high-performance energy storage. By establishing a clear structure–property relationship where PAN impregnation optimises free-volume porosity and polar wettability, while the DOPO-functionalized polyimide backbone reinforces thermal and mechanical integrity, this study provides a blueprint for engineering multifunctional battery separators. Crucially, this design overcomes concurrent safety and electrochemical bottlenecks, laying the groundwork for its future potential to be rigorously tested in high-voltage, full-cell LMB configurations to realise safe, high-energy-density commercial power sources.