Microfluidic-Assembled Covalent Organic Frameworks@Ti₃C₂T_x MXene Vertical Fibers for High-Performance Electrochemical Supercapacitors

The delicate design of innovative and sophisticated fibers with vertical porous skeleton and eminent electrochemical activity to generate directional ionic pathways and good faradic charge accessibility is pivotal but challenging for realizing high-performance fiber-shaped supercapacitors (FSCs). Here, hierarchically ordered hybrid fiber combined vertical-aligned and conductive Ti₃C₂T_x MXene (VA-Ti₃C₂T_x) with interstratified electroactive covalent organic frameworks LZU1 (COF-LZU1) by one-step microfluidic synthesis is developed. Due to the incorporation of vertical channels, abundant redox active sites and large accessible surface area throughout the electrode, the VA-Ti₃C₂T_x@COF-LZU1 fibers express exceptional gravimetric capacitance of 787 F g⁻¹ in a three-electrode system. Additionally, the solid-state asymmetric FSCs deliver a prominent energy density of 27 Wh kg⁻¹, capacitance of 398 F g⁻¹ and cycling life of 20 000 cycles. The key to high energy storage ability originates from the decreased ions adsorption energy and ameliorative charge density distribution in vertically aligned and active hybrid fiber, accelerating ions transportation/accommodation and interfacial electrons transfer. Benefiting from excellent electrochemical performance, the FSCs offer sufficient energy supply to power watches, flags, and digital display tubes as well as be integrated with sensors to detect pulse signals, which opens a promising route for architecting advanced fiber toward the carbon neutrality market beyond energy-storage technology.