Interfacial Polymerization-Modified Polyetherimide (PEI) Separator for Li–O2 Battery with Boosted Performance

Lithium–oxygen (Li–O2) batteries, having an ultrahigh theoretical energy density (3500 Wh kg–1), have gained a lot of attention. However, its application is seriously obstructed by pivotal issues like instability of lithium metal anode, low energy efficiency, and electrolyte decomposition. Herein, a separator modification method based on interfacial polymerization (IP) was proposed by us to solve these issues. The obtained interfacial polymerization layer shows good ion-selective permeability on the surface of the polyetherimide (PEI) separator, and the ion transport of the larger EMIM+, TFSI–, and BF4– between the electrodes is greatly inhibited. Consequently, the representative P2-PEI separator presents the best cycle performance and the Li–O2 battery assembled with it can stably operate over 135 cycles, even under a current density of 0.05 mA cm–2 and a limited specific capacity of 1000 mAh g–1.