Structural and material optimization approaches for nanofiber separators in all-textile supercapacitors

All-textile supercapacitors were fabricated using carbon fiber nonwoven electrodes in combination with electrospun nanofiber separators. Four polymers—polyurethane, polyacrylonitrile (PAN), polyvinylidene fluoride, and polyvinyl alcohol (PVA)—were evaluated as potential separator materials. PVA nanofiber webs were subjected to thermal treatment and glutaraldehyde (GA) crosslinking to enhance their water stability. Constant current charge–discharge (CCCD) measurements revealed that the tested PAN and thermally treated PVA separators were electrochemically nonfunctional due to short-circuiting, whereas GA-crosslinked PVA exhibited stable charge–discharge behavior within a 1 V operating window. Within the framework of this study, effective electrochemical performance was observed only when the separator thickness exceeded 32 μm, corresponding to an average pore size of approximately 0.37 μm. After 24 h of electrolyte exposure, the GA-crosslinked PVA separator maintained structural integrity and exhibited an increase in capacitance from 0.385 to 0.420 mF/cm2, indicating chemical resistance and sustained electrochemical performance. These results demonstrate that GA-crosslinked PVA nanofiber separators are promising materials for flexible all-textile supercapacitors in wearable energy storage applications.