Strain engineering of Bi2Se3 anode for ultrafast sodium storage

High-performance electrodes based on the conversion or alloying mechanisms have attracted much attention owing to their high theoretical capacity, but the development of fast charging conversion or alloying type electrodes by simple methods remains a great challenge. Herein, a new type of strained bismuth selenide material (s-Bi2Se3) was obtained through post heat treatment process. Due to its unique structural advantages including large interlayer spacing and narrow band gap, ion diffusion and electron transfer accelerated significantly. Meanwhile, the lattice strain in materials is thermodynamically favorable for the redox reaction to proceed. The as prepared s-Bi2Se3 exhibits ultrafast electrochemical reaction kinetics when it is used as an anode for sodium-ion batteries (SIBs) and retained a high reversible specific capacity of 332.7 mAh/g even at the ultrahigh current density of 30 A/g after 1000 cycles. Especially, the Na-ion full cell was assembled with a cathode of Na3V2(PO4)3@C, showing excellent electrochemical performance (176.2 Wh/kg at 0.2 A/g and 99.7 Wh/kg at 1662.4 W/kg). In addition, the high-performance mechanism was explored through electrochemical tests and characterizations, which provided an important theoretical basis for the application of SIBs.