A Novel EVOH-Coated Polyethylene Separator for High-Performance Lithium-Ion Batteries

Traditional polyolefin separators used in lithium-ion batteries (LIBs) suffer from poor wettability with electrolytes, significantly hindering their application in high-energy density batteries. To address this issue, we developed an EVOH-coated polyethylene separator using a phase separation method. The modified separator retains mechanical properties such as tensile strength and puncture resistance similar to the base separator. The soft EVOH coating enhances the separator’s ability to conform to the electrode under stress, improving contact and overall battery performance. Notably, the EVOH coating significantly enhances the separator’s electrolyte wettability, resulting in an electrolyte uptake of 253%. The abundant hydroxyl groups within the coating improve the electrochemical performance, leading to enhanced discharge rate capacity and cycling stability. The lithium-ion transference number of the modified separator increased to 0.76. The straightforward preparation method and superior performance of the EVOH-coated separator suggest its promising application in high-performance LIBs.