Rechargeable Aqueous Lithium–Air Batteries Using Polymeric Membrane Separator: Effect of Organic Electrolytes in Anolyte

Rechargeable aqueous lithium–air (aqueous Li–air) batteries are a promising high‐energy alternative to lithium‐ion batteries due to high specific energy density. Aqueous Li‐air batteries with long‐cycling performance, minimal degradation, suppressed dendrite growth, and high safety are essential for practical applications. The separator between anolyte and catholyte plays a critical role in ensuring both the performance and safety of the battery. This study investigates a novel water‐impermeable lithium‐ion‐conductive polymer film (thickness < 10 μm), proposed by Toray Industries, Inc. (Japan), as a successful replacement for conventional ceramic separators. The cell performance of the aqueous Li–air with a lithium metal, an anolyte, a polymer membrane separator, a 1 M LiOH‐10 M LiCl catholyte, and carbon air electrode was examined as a function of the anolyte. All experiments were operated at 0.5 mA/cm 2 and conducted at 25°C. A stable average open circuit voltage (OCV) of 3.0 V was observed. The battery was successfully operated for 211 cycles at 0.5 mA/cm 2 with ethoxyethane/diethyl ether (EE), while 100 stable cycles were observed with 1,2‐diethoxyethane (DEE).