Free-standing SnNb2O6@CSN film as flexible anode for high performance sodium-ion batteries

Free-standing electrodes are promising candidates for flexible rechargeable batteries, toward the application of flexible energy storage devices, due to their merits of additive-free, lightweight, and high energy density. Herein, we report a free-standing SnNb2O6@CSN flexible film with SnNb2O6 encapsulated in 3D carbon skeleton nanofibers by electrospinning and carbonization processes as flexible anode for sodium-ion batteries (SIBs). The 3D carbon skeleton nanofibers serve as ion/electron transport pathway to improve the electrochemical reaction kinetics and meanwhile alleviate the volume changes of SnNb2O6 during charge-discharge processes. The as-constructed half-cell (SnNb2O6@CSN‖Na) exhibits excellent cycling stability of 99.2 mAh/g at 0.5 A/g after 950 cycles (coulombic efficiency of ∼100%) and a high rate performance of 108.6 mAh/g at 10 A/g. In addition, the pouch cell can light up the LEDs at different bending angles (0°, 90°, 180°). This research shows a promising anode material for flexible energy storage electronics.