An Amino‐Modified <scp>ZIF</scp> ‐67/Aramid Nanofiber Coating for High‐Performance Lithium Battery Separators

ABSTRACT To improve the thermal safety, hydrophilicity and ion transport performance of polypropylene (PP) separators in lithium‐ion batteries, a composite coating was developed using amino‐modified zeolitic imidazolate framework material (ZIF‐67‐NH 2 ) and aramid nanofiber (ANF). The coating was applied to the PP separator via a two‐step sequential method: (1) ANF dispersion was coated onto the PP substrate to form a support network layer with high mechanical strength and excellent thermal stability; (2) ZIF‐67‐NH 2 dispersion was uniformly loaded on the ANF layer to construct a functional layer with high specific surface area, regular pore structure and rich active sites. Amino modification of ZIF‐67 significantly improved its electrolyte affinity and lithium‐ion transport activity. Compared to the pristine PP separator, the modified separator exhibited a thermal shrinkage rate of only 31% at 170°C, indicating superior thermal stability. The water contact angle reached 20°, indicating significantly enhanced wettability. The impedance decreased from 105.6 to 71.2 Ω, and the apparent ionic conductivity increased from 0.0118 to 0.0877 mS/cm. In the cycling test, the battery using the modified separator exhibited an initial discharge capacity of 80 mAh/g, which is approximately 8% higher than that of the battery using the pristine PP separator (73.9 mAh/g), also demonstrating improved capacity retention and stability.