Reliable coaxial wet spinning strategy to fabricate flexible MnO2-based fiber supercapacitors

With the rapid development of electronic technique, wearable energy conversion and storage devices are facing huge challenges. Particularly, fiber supercapacitors have advantages of small size, light weight, high flexibility, fast charge/discharge process, high power density, long cycle life and wide operating temperature, showing considerable application prospect in the smart wearable field. This work proposes a strategy to fabricate MnO2, MnO2/PANI and MnO2/GN fiber electrodes via coaxial wet spinning technology, in which the electrochemical active materials could be wrapped into CMC layer perfectly, ensuring the structure stability of fiber electrodes effectively. And a series of MnO2-based parallel fiber supercapacitors are further assembled. After optimization of mixing ratios, the MnO2/PANI fiber supercapacitor with mixing-ratio of 1:1 exhibits specific capacitance of 0.68 μF·cm−1 at 0.25 μA·cm−1, and the MnO2/GN fiber supercapacitor with mixing-ratio of 9:1 presents 1.23 μF·cm−1at the same current density, which are both higher than that of pure MnO2 fiber supercapacitor (0.59 μF·cm−1), proving significant enhancement of electrochemical performance due to the introduced PANI or GN. Therefore, this work provides a reliable guidance for design and application of wearable fiber supercapacitors.