One‐Meter‐Long, All‐3D‐Printed Supercapacitor Fibers Based on Structurally Engineered Electrode for Wearable Energy Storage

Abstract Fiber‐shaped energy storage devices have great potential for use as an intelligent power source for futuristic wearable technology. To produce high‐performance fiber‐shaped energy storage devices, a thin fiber material with a high energy density, shape adaptability, and longevity is critical. Herein, 3D fiber‐shaped supercapacitors (SCs) comprising MXene‐PEDOT:PSS active electrodes made using the 3D‐direct‐ink‐writing (DIW) technique are demonstrated. Embedding a silver (Ag) current collector in the active electrode facilitated faster charge transport in the fiber‐shaped 3D‐SCs, enabling them to create a unique 3D‐electrode structure that solves the thickness and length problem of electrode‐dependent capacitance in fiber‐shaped devices. At one‐meter long, the fully‐printed fiber‐shaped 3D‐SC exhibits a low charge transfer resistance that leads to the high areal capacitance of 1.062 F cm −2 and gravimetric capacitance of 185.9 F g −1 , with a high areal energy density of 94.41 µWh cm −2 at a power density of 1,142 µW cm −2 . The fiber‐shaped 3D‐SCs also exhibit excellent electrochemical and mechanical stability at different temperatures in air and water. With their unique electrode structure and uninterrupted power supply, these R2R 3D‐DIW printed fiber‐shaped SCs can boost the development of innovative textile technology.