3D cellulose network confining MXene/MnO₂ enables flexible wet spinning microfibers for high-performance fiber-shaped...

Fiber-shaped Zn-ion capacitors (FSZICs) have shown great potential in wearable electronics due to their long cycle life, high energy density, and good flexibility. Nevertheless, it is still a critical challenge to develop a conductive fiber with long size and high mechanical properties as the FSZIC cathode using sustainable and low-cost materials. Herein, regenerated cellulose (RC) -based conductive microfibers are prepared by a simple, continuous, and scalable wet spinning process. The 3D nanoporous networks of RC caused by physical self-cross-linking allow MXene and MnO₂ to be uniformly and firmly embedded. The rapid extrusion and limited drying result in the highly aligned structure of the fibers, endowing the hybrid fiber with an ultra-high tensile strength (145.83 Mpa) and Young's modulus (1672.11 Mpa). MXene/MnO₂-RC-based FSZIC demonstrates a high specific capacitance of 110.01 mF cm^-3, an energy density of 22.0 mWh cm^-3 at 0.57 A cm^-3 and excellent cycling stability with 90.5 % capacity retention after 5000 cycles. This work would lead to a great potential of cellulose for application in next-generation green and wearable electronics.