Electrostatic self-assembled SnSe@Ti3C2 with 3D network structure towards ultra-stable and high rate capability sodium ion storage

Abstract

SnSe is an emerging anode for sodium ion storage due to its abundant resource, safety, reliability, narrow bandgap (0.9 eV) and outstanding theoretical capacity (780 mAh g−1). Nevertheless, the dissolution of discharge products (Na2Se) and the structure collapse during Na+ insertion/extraction result in a dramatic decline of capacity. Herein, SnSe nanosheets anchored on Ti3C2 (SnSe@Ti3C2) with a three-dimensional (3D) network structure is prepared by electrostatic self-assembly and annealing strategy. Ti3C2 with abundant functional groups and open pores facilitates the full reaction of the electrode and electrolyte. In addition, the 3D network structure of Ti3C2 substantially reduces the structural collapse and aggregation of SnSe as well as improves charge transfer kinetics of the composites. The synergistic effect between Ti3C2 with 3D skeleton and SnSe leads to ultra-long cycling stability (240.1 mAh g−1 at 0.1 A g−1 after 1350 cycles) and superior rate capability (128.6 mAh g−1 at 5.0 A g−1). SnSe@Ti3C2//AC sodium ion capacitor (SIC) possesses a capacity retention of 73.8% after 10000 cycles at 1.0 A g−1. The proposed design provides a broad prospect for transition metal dichalcogenide (TMD) based composites as superior anodes for sodium ion storage.