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

Abstract

Lithium−oxygen (Li−O 2 ) 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 BF 4 − between the electrodes is greatly inhibited. Consequently, the representative P2-PEI separator presents the best cycle performance and the Li−O 2 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 .