This study outlines the successful fabrication of composite membrane using rice-straw lignin/polyacrylonitrile (L-PAN) via electrospinning method, and evaluated as a lithium-ion battery separator. L-PANs exhibited higher porosity and superior electrolyte wettability compared to the commercial Celgard 2300. Remarkably, even after exposure to 150 °C for an hour, L-PANs showed minimal changes, whereas Celgard 2300 experienced notable shrinkage. As a separator for Li/LiFePO4 batteries, L-PANs demonstrated outstanding capacity retention of 97.7 % over 200 cycles and superior cycling performance compared to Celgard 2300. Collectively, this research offers a promising approach to valorizing waste rice straw resources and expanding the application of lignin in the field of lithium-ion battery.