Robust MXene fiber empowered by rational formulation of spinning stock and optimization of interfacial cross-linking for efficient charge storage

Ti₃C₂T_X nanosheets are promising candidates upon the increasing demands of flexible electrode materials for advancing portable/wearable fibrous energy storage devices because of their outstanding electrical conductivity and high theoretical capacitance; nevertheless, the weak interlayer interaction and the requirement of suitable interlayer spacing make it difficult to develop strong MXene fibers with desirable charge storage ability. Herein, we develop a robust MXene fiber optimized by interfacial cross-linking through directly coagulating the rationally formulated spinning stock of Ti₃C₂T_X nanosheets, polyvinyl alcohol and glutaraldehyde (MXene-PVA-GA, denoted as MPG) in acetic acid. The modified fibers demonstrate significantly enhanced mechanical strength, reaching 176.5 MPa, while maintaining a capacitance up to 1225.0 F cm⁻³ at 4 A cm⁻³, outperforming the pure MXene fibers (26 MPa and 647.0 F cm⁻³). The fabricated FSC achieves a volumetric capacitance reaching 281.0 F cm⁻³ at 1 A cm⁻³, and an energy density up to 0.065 Wh cm⁻³ under a power density of 7.2 W cm⁻³, underscoring its feasibility for deployment in flexible and smart wearable technologies. This work offers valuable guidance for developing robust MXene-based fibers with enhanced mechanical properties and electrochemical performance, supporting future applications in wearable and textile supercapacitors.