From Li-O₂ to Li-Air Batteries: Challenges and Progress on Oxygen-Permeable Membranes

Given the escalating global energy scarcity, there is a pressing need for advanced energy supply solutions to accommodate the evolving transportation landscape. Consequently, there has been a surge in interest surrounding lithium metal batteries, particularly Li-air batteries (LABs), which researchers have showcased for their remarkable energy density, reaching up to 3500 Wh kg^-1. However, despite decades of dedicated research efforts, LABs have not yet achieved practical commercialization as a result of challenges, such as external moisture infiltration and sluggish electrochemical kinetics within the battery. In this review, we elucidate the challenges linked with oxygen-permeable membranes (OPMs) in practical LABs, particularly when operating in open environments. Subsequently, we comprehensively evaluate all developed OPMs to date, aiming to enhance the performance of LABs, focusing on both outer- and inner-type OPMs. Finally, critical issues pertaining to oxygen selectivity, permeability, water resistance, and electrolyte compatibility are underscored, with perspectives offered on the development of high-performance OPMs.