Self-assembled Aramid-Based Nanofiber Separator for High Safety Lithium Metal Batteries

Higher safety standards are essential for the development of high-energy-density batteries within the rapidly advancing electric vehicle and large-scale energy storage industries. Herein, we report a novel, simple, and successive process to coat the 1,3,5-triaminophenoxybenzene (TAB) covalently crosslinked poly (p-phenylene terephthamide) (PPTA) onto commercial polyethylene (PE) as separators (denoted as PPTA/TAB@PE) for high safety lithium (Li) metal batteries (LMBs). Without any additional binder, the PPTA/TAB nanofiber coating layer sticks to porous PE separators by physical anchoring, improving the heat resistance and mechanical properties of the composite separators. Meanwhile, migration routes for Li-ions are guaranteed by the porous structure assembled of the fibrillar units during the nonsolvent induced phase separation. The designed PPTA/TAB@PE separator shows a high Li-ion transference number of 0.65. As a result, the symmetric Li||Li cell with PPTA/TAB@PE separator demonstrates stable Li plating and stripping. The associated Li||LiFePO₄ and Li||LiNi_0.8Co_0.1Mn_0.1O₂ half cells exhibit high capacity, excellent rate performance, and remarkable cycling stability, significantly surpassing those of cells using commercial separator. This research presents an innovative method for designing functionalized separators to enhance the performance of LMBs.