Lithiated poly (ether ether ketone) separators with excellent thermal stability and electrolyte wettability for lithium-ion battery

The separators with excellent thermal stability and electrolyte wettability are pivotal for ensuring the safety and performance of lithium-ion batteries (LIBs). Poly (ether ether ketone) (PEEK) is a potential separator material that meets these criteria. However, the poor solubility and high melting temperature of PEEK limit its practical production and application. Herein, we report a safe and convenient strategy to fabricate lithiated poly (ether ether ketone) (LPEEK) separators via lithiation of PEEK and thermally induced phase separation below the melting point. And the pore structure of LPEEK separators can be regulated by the amount of polyvinylpyrrolidone. Compared with commercial polypropylene (PP) separators and other PEEK separators, our LPEEK separators exhibit excellent thermal stability (LPEEK, almost no change at 200 °C; PP, shrink 4.4% at 100 °C) and electrolyte wettability (electrolyte contact angle: LPEEK, 0°; PP, 37.9°). Meanwhile, the LPEEK separators can still be used normally after 200 °C high-temperature treatment and are promising candidates for the LIB separators used at high temperatures. The proposed method holds promise for the industrial production of PEEK separators. Graphical abstract