Poly(ether ether ketone) Conferred Polyolefin Separators with High Dimensional Thermal Stability for Lithium-Ion Batteries

The traditional polyolefin separators used in lithium-ionbatteries(LIBs) are plagued by limitations such as poor wetting of electrolytesand insufficient thermal stability, hindering the progress of LIBs.To overcome these limitations, we have developed a modified phaseinversion technique to efficiently and durably coat polyolefin separatorswith poly(ether ether ketone) (PEEK). The resulting PEEK-coated polyolefinseparators exhibit mechanical properties similar to those of unmodifiedpolyolefin separators, with comparable tensile strength and modulus.Furthermore, the PEEK coating provides outstanding thermal stability,as the modified separators maintain their stability even at temperaturesup to 200 & DEG;C, which is among the best results reported for polyolefin-basedseparators. In addition, the PEEK coating enhances ionic conductivityby more than 100% compared to polyolefin counterparts, leading tosignificant improvement in the electrochemical performance of prototypehalf cells. The modified phase inversion technique presented hereoffers a practical solution for coating polyolefin separators withfunctional polymers, paving the way for next-generation separatormaterials.