Resin-silica composite nanoparticle grafted polyethylene membranes for lithium ion batteries

To avoid the peeling-off of ceramic nanoparticles (NPs) from polyolefin membranes usually occurred in commercially available ceramic NPs coated polyolefin separators for lithium batteries, we propose a simple one-pot in-situ reaction method to modify commercial polyethylene (PE) separators by surface grafting 3-Aminophenol/formaldehyde (AF)/silica (SiO2) composite NPs. The AF/SiO2 composite NPs form self-supporting connected pores on the modified layer of the separator surface, which ensures the transportation of Li+. Moreover, the PE@AF/SiO2 separators has higher electrolyte wettability and compatibility than neat PE separators attributed to the plentiful polar functional groups in the AF/SiO2 layer and AF/SiO2 composite NPs, resulting in higher lithium ion transference number (tLi+= 0.62) and ionic conductivity (sigma = 0.722 mS cm(-1)). More importantly, the discharge capacity, capacity retention rate and coulombic efficiency (136.2 mA h g(-1), 87.9% and 99%, respectively) after 200 cycles of Li|NMC half batteries with PE@AF/SiO2 separators, are all more excellent than that with the pure PE separator (125 mA h g(-1), 83.1% and 85%, respectively). Our results show that the PE@AF/SiO2 separators obtained by this modification method have higher electrochemical stability in the lithium battery system.