A high-safety lithium-ion battery electrospun separator with Si₃N₄-assisted sulfonated poly(ether ether ketone) for...

The uncontrolled lithium (Li) dendrite growth significantly impacts the safety performance of polymer separators. To mitigate this growth, this study introduces Si₃N₄ into sulfonated poly(ether Ether Ketone) (SPEEK) and prepares Si₃N₄/SPEEK composite separators via electrospinning. At the interface between the Si₃N₄/SPEEK separator and the Li anode, the Si nanowires that form impede Li dendrite growth, thereby enhancing the electrochemical performance of lithium-ion batteries (LIBs). The Li deposition test of the 10 % Si₃N₄/SPEEK separator can operate for 1000 h without short-circuiting. Additionally, the LiFePO₄||Li cell with the 10 % Si₃N₄/SPEEK separator shows improved initial discharge capacity (157.8 mAh g^-1 at 1C) and superior rate performance (125 mAh g^-1 at 10C). Moreover, the nano-scale Si₃N₄ endows the separator with robust thermal and mechanical properties. The FLIR observations reveal that the 10 % Si₃N₄/SPEEK separator maintains uniform thermal distribution and structural integrity even at 300 °C, ensuring safe battery operation at high temperatures. The additional load of the 10 % Si₃N₄/SPEEK separator can reach 10.2 mN, which enhances the puncture resistance of the separator. This work provides a solid approach for the application of SPEEK as a high-safety and high-rate LIB separator.