The fabrication of high-performance α-Al2O3 coated PE separator for lithium-ion batteries based on multiple hydrogen bonds

Abstract

The separator acts as a crucial role in lithium-ion batteries (LIBs). However, commercial separators possess serious shortcomings such as poor thermal stability and compatibility with liquid electrolyte. Although the coating of ceramic powder on the separator can alleviate these disadvantages, it is still challenging to solve the problem of ceramic coating falling off the separators surface. Herein, by improving the surface structure of PE separator and α-Al2O3 particles, KH550 modified α-Al2O3 (mAl2O3) is anchored on the surface of dopamine modified PE separator (PDA-PE) with multiple hydrogen bonds to prepare high-performance battery separator (PDA@mAl2O3-PE). The results demonstrate that the PDA@mAl2O3-PE separator has excellent thermal stability, mechanical performance and electrolyte wettability. Moreover, the ionic conductivity of the PDA@mAl2O3-PE separator increases from 0.531 mS cm−1 for the pristine PE separator to 0.693 mS cm−1. When the PDA@mAl2O3-PE separator is used in LIBs, the LiCoO2/Li batteries present superior cycling capability with a discharge capacity of 132 mAh g − 1 at 1 C after 100 cycles and the capacity retention rate is 95.8%, much higher than that of the batteries with PE separator (86.4%), suggesting that the PDA@mAl2O3-PE separator has a stable ceramic surface anchored by multiple hydrogen bonds and has greater compatibility with electrolyte, leading to a quicker lithium-ion diffusion and outstanding cycling stability.