Scalable one-step coaxial wet spinning of regenerated cellulose fiber supercapacitors with integrated electrolyte-electrode interfaces

Flexible fiber supercapacitors (FSCs) have emerged as promising candidates for sustainable power sources in wearable electronics, owing to their excellent wearability and integration potential. However, scalable application remains hindered by the complexity of integrating fiber electrodes and solid electrolytes through conventional multistep fabrication processes. Here, we present a novel “all-in-one” strategy for the scalable fabrication of solid-state symmetric FSCs via a one-step coaxial wet spinning technique. By co-extruding Ti₃C₂Tx/polyaniline (MXene/PANI) composites and a cellulose-based electrolyte solution, both the electrode and electrolyte components are synchronously formed and seamlessly integrated in situ during fiber formation, circumventing the need for post-processing or step-by-step assembly. This integrated spinning approach not only streamlines fabrication but also enhances material cohesion and optimizes the utilization of electroactive components, thereby improving the overall electrochemical performance and mechanical robustness of the resulting FSCs. The as-prepared devices exhibit outstanding cycling stability, with 91.7% capacitance retention over 10,000 cycles, outperforming previously reported fiber-based supercapacitors. Furthermore, the FSCs demonstrate reliable operation when integrated into garments to power Light Emitting Diode (LED) modules and electronic watches, underscoring their practical applicability. This work offers a scalable and efficient pathway for prototyping on-demand FSCs as available wearable building blocks, paving the way for smart textiles and integrated power systems.