3D electronic channels wrapped Large-Sized SnSe as flexible electrode for Sodium-Ion batteries

Transition metal selenides are regarded as the promising anode materials for sodium-ion batteries (SIBs) due to their high theoretical capacitie. However, they still suffer from some fatal flaws including short lifetime and sluggish cycling kinetics. Herein, a free-standing, binder-free electrode was developed by electrospinning and subsequent thermal treatment process, in which three-dimensional (3D) N-doped carbon nanofibers and tin selenide are cross-linked with each other (SnSe/NCF). The synergistic effect of SnSe microsheets and carbon fibers shortens the ion transport channel and increases more active sites. N-doped carbon network not only improves electrical conductivity but also prevents pulverization of the material. The as-prepared SnSe/NCF electrodes exhibit good electrical conductivity and flexibility owing to the highly carbonized carbon nanofiber network. The SnSe/NCF electrode exhibits superior specific capacity with (576.7 mAh g-1 at 0.2 A g-1), ultra -long lifetime (286.4 mAh g-1 after 2100 cycles at 2.0 A g-1) and excellent rate performance (576.7 mAh g-1 at 5 A g-1) as a stand-alone anode for SIBs. This work provides a promising approach for developing flexible energy storage devices.