Reducing Water Exchange by Polyacrylic Acid Based Water‐Vapor‐Resistant Membrane in Zinc/Air Battery

Zinc/air batteries have received extensive attention due to their low cost, high safety, and high energy density. However, as the zinc/air battery is operated in the practical environment, water exchange between the battery and the environment occurs and affects the specific capacity and service life of the battery. In this paper, high relative‐humidity water‐vapor‐resistant membrane is prepared based on water‐absorbent polyacrylic acid. Using this membrane, water exchange is effectively reduced due to the decreased humidity gradient through gas diffusion electrode. When the thickness of the PAA wet film is 150 μm, the water vapor transmission rate (WVTR) reduced to 51 % of the blank. The excellent discharge performance of zinc/air battery is also achieved with the discharge voltage plateau of 1.10 V and the specific capacity of 612.5 mAh g−1 under the current density of 20 mA cm−2, which is 33.8 % higher than that without PAA membrane. Water‐vapor‐resistant membrane prepared by polyacrylic acid (PAA) reduces 49 % water vapor transmission in zinc/air battery by reducing the water vapor transmission channel and the humidity gradient inside and outside the gas diffusion electrode, which increases the discharge voltage plateau and specific capacity to 1.10 V and 612.5 mAh g−1 under the current density of 20 mA cm−2.