High-performance Bi₂Se₃/MXene/SWCNT heterostructures as binder-free anodes in lithium-ion batteries

Bi₂Se₃, MXenes, and SWCNTs are promising potential alternatives to replace the conventional graphite in the anodes of lithium-ion batteries (LIBs) and enhance their performance. However, all these materials have drawbacks, such as large volume expansion and Se dissolution (Bi₂Se₃), large irreversible capacity (SWCNTs), and poor specific capacity (MXenes). In this work, a combination of nanostructured Bi₂Se₃ and MXenes with SWCNTs in Bi₂Se₃/MXene/SWCNT heterostructures is used as a novel architecture for binder-free anode material in non-aqueous LIBs. Bi₂Se₃/MXene/SWCNT heterostructures with different Bi₂Se₃:MXene:SWCNT mass ratios were fabricated by direct physical vapour deposition of Bi₂Se₃ nanostructures onto MXene/SWCNT networks. Bi₂Se₃/MXene/SWCNT heterostructures showed improved electrochemical performance in comparison with the individual components of the heterostructures. This enhancement can be attributed to the high electrode/electrolyte contact area provided by the nanostructured materials, leading to a substantial capacitive contribution to charge storage. In addition, the formation of Se–C bonds on SWCNT surfaces prevented the dissolution of Se. The best performance was shown by Bi₂Se₃/MXene/SWCNT heterostructures with the mass ratio of 1:1:2, which reached capacity of 738 mA h g^-1 at 0.1 A g^-1 after 100 cycles. Moreover, after 900 cycles at 10.0 A g^-1 current density, these heterostructures retained an excellent capacity of 320 mA h g^-1. This performance indicates significant potential for Bi₂Se₃/MXenes/SWCNTs heterostructures as binder-free anodes for high-rate-performance lithium-ion batteries.