Polydopamine-assisted in situ formation of dense aramid nanofibers layer on polyethylene separator for lithium-ion battery

Herein, we report a modified polyethylene (PE) separators via in situ polymerization of polydopamine (PDA) and coating of dense aramid nanofibers (ANFs) on the surface of PE separator. Due to the unique hydrophilic performance and cooperative effect of PDA and ANFs, the wettability and migration ability of lithium ion of the modified PE separator were obviously enhanced. Moreover, the modified PE separator have the lower thermal shrinkage, the higher melting temperature and decomposition temperature, and excellently electrolyte wettability than pristine PE separators. The capacity of the modified PE separator remains 140.29 mAh g⁻¹ after 200 cycles at 1.0°C, and the coulombic efficiency also maintain more than 78.86%. In addition, the modified PE separator exhibits a higher lithium-ion transfer number, outstanding ionic conductivity (2.390 × 10⁻⁴ S/cm) and small interfacial resistance (−83.85 Ω) due to its excellently electrochemical properties. Thus, the modified PE separator has great potential to fabricate the high quality separator materials for designing and developing lithium-ion batteries.