Chitosan derived nitrogen and oxygen dual-doped hierarchical porous carbon/Ti3C2Tx MXene fiber for flexible cable shaped lithium-selenium battery

Pursuing flexible, matchable and miniaturized power supply with high capacitance is necessary for portable electronics as long-term period of energy source in wearable system. Here, a hierarchical Se/chitosan derived nitrogen and oxygen dual-doped porous carbon/Ti3C2Tx (Se-NOCT) fiber is proposed via microfluidic spinning method prior to co-heating process for the fiber cathode of cable-shaped lithium‑selenium (LiSe) battery. Due to the interconnected structure, consecutive conductive frameworks and good synergistic effect, the fabricated Se-NOCT fibrous electrode shows excellent ions diffusion kinetics, fast electron migration rate and strong polyselenide adsorption ability proving by density functional theory (DFT) calculations. As a result, an admired specific capacitance (866 mAh g−1 at 0.1 A g−1), favorable rate performance (256 mAh g−1 at 2 A g−1) and long-term cycling property (226 mAh g−1 after 500 cycling) can be achieved for the Se-NOCT electrode. More importantly, after assembling to the fibrous LiSe battery, the energy storage device not only presents stable operation at bending to 180o, 97.3 % capacitance retention after 100 times bending and impressive launderability, but also weave into the garment and support various electronics. Thus, customized flexible electrode provides a bright future for the progress of fiber shaped LiSe battery in smart wearable system.