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 (SiO 2 ) composite NPs. The AF/SiO 2 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/SiO 2 separators has higher electrolyte wettability and compatibility than neat PE separators attributed to the plentiful polar functional groups in the AF/SiO 2 layer and AF/SiO 2 composite NPs, resulting in higher lithium ion transference number ( = 0.62) and ionic conductivity (σ = 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/SiO 2 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/SiO 2 separators obtained by this modification method have higher electrochemical stability in the lithium battery system.