Highly Flexible Fiber Supercapacitors with Ultra-High Energy Density for Energy Storage Electronic Textiles

Fiber-shaped supercapacitors (FSCs) have emerged as promising energy storage solutions for powering miniaturized wearable electronic textiles. However, the scalable fabrication of flexible fiber electrodes with a high energy density and excellent storage remains challenging. Herein, we report a scalable strategy for developing FSCs with a high energy density and mechanical flexibility. This approach integrates wet-spun MXene nanosheets/slide-ring polyrotaxane/PEDOT:PSS hybrid fibers with in situ silver nanowire (AgNW) functionalization and helical twisted Cu fiber current collectors. The resulting fibers exhibit high electrical conductivity, large specific surface area, and outstanding strength and toughness. After twisting and assembly with Cu fiber, the FSCs show a high volumetric capacitance of 860.1 F cm^-3 at 5 mV s^-1, with 96.6% retention after 10,000 bending cycles. The FSCs also achieve an energy density of 76.6 mWh cm^-3 and power density of 776.5 mW cm^-3, surpassing those of most reported flexible FSCs. These properties enable broad wearable device applications.