Electrochemical properties of bismuth chalcogenide/MXene/CNT heterostructures for application in Na-ion batteries

The development of high-performance anodes for sodium-ion batteries (SIBs) has recently attracted great attention. Most of the proposed anode materials for SIB systems suffer from insufficient electrical and mechanical contact of the active material with the current collector causing low reversible capacity and short lifespan. To solve this issue, an innovative approach could be the direct synthesis of the active material around and on the top of an electrically conductive network. The nanostructuring with SWCNTs and MXenes increases the active surface area, improves expansion/contraction properties, and establishes a direct mechanical and electrical contact. In this work the performance of binder-free Bi₂Se₃/SWCNT and Bi₂Se₃/MXene/SWCNT anode materials, which were synthesized by the direct physical vapor deposition of Bi₂Se₃ nanostructures on SWCNT and MXene/SWCNT network systems, was investigated. The results showed that the Bi₂Se₃/SWCNT electrode with the mass ratio of (1:1) exhibits excellent rate performance and high discharge capacity in the short-term (0.1 A g⁻¹) and long-term (5.0 A g⁻¹) cycling by delivering 247 and 120 mAh g⁻¹ respectively demonstrating its perspectives for the application as an anode in SIBs.