Aramid and zirconia coated separator for enhanced electrochemical performance of lithium-ion batteries

In this study, a novel porous composite separator was fabricated by depositing biomass-derived aramid-zirconia (AF-ZrO₂) on both sides of a commercial polyethylene (PE) separator. The influence of the aramid-zirconia coating on the properties of the resulting PE@AF-ZrO₂ composite separator was systematically investigated. The results demonstrate that the coating significantly enhances wettability, thermal stability, electrical insulation and mechanical properties relative to the pristine PE separator, resulting in enhanced electrochemical performance in both Li‖LiFePO4 coin cells and LiFePO₄‖graphite pouch cells. Specifically, the PE@AF-ZrO₂ composite separator exhibits an electrolyte uptake of 381%, an ionic conductivity of 0.306 mS cm^-1, a dielectric strength of 266 V μm^-1 and a tensile strength of 189.5 Mpa. In Li‖LiFePO4 coin cells, the PE@AF-ZrO₂ separator delivers a discharge capacity of 128.2 mAh g^-1 at a 10C discharge rate. Furthermore, LiFePO₄‖graphite pouch cells using the PE@AF-ZrO₂ separator show exceptional cycling stability, with 93.5% initial energy capacity retention after 1200 cycles. These results suggest that coating a PE separator with an aramid-zirconia layer represents an effective strategy to create a robust, high-performance composite separator, highlighting its promising commercial potential for lithium-ion batteries (LIBs).