Mussel-Inspired Polydopamine-Assisted in Situ Formation of Dense Aramid Nanofibers Layer on Polyethylene Separator for Lithium-Ion Battery

Abstract

The separator, as a physical barrier, is of great significance to allow lithium-ion migration of lithium-ion battery. However, the current commercial polyethylene (PE) separator with low melting temperature and poor electrolyte wettability cannot satisfy the needs of the high performance for the lithium ion. Herein, a dense aramid nanofibers (ANFs) coating layer is in situ designed and fabricated by the working together with polydopamine (PDA) 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 modification PE separator were obviously enhanced. Moreover, the obtained PE/PDA/ANFs 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 modification 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 PE/PDA/ANFs separator exhibits a higher lithium-ion transfer number, outstanding ionic conductivity (2.390×10-4 S cm-1) and small interfacial resistance (-83.85 Ω) due to its excellently electrochemical properties than pristine PE separator. Thus, the modified PE separator has great potential to fabricate the high quality separator materials applied to lithium-ion batteries.

Keywords: Aramid nanofibers, Polydopamine, Lithium-ion battery, Separator