Bi2Se3@SWCNT heterostructures with beyond theoretical capacity as perspective binder-free anodes for lithium-ion batteries

Bi2Se3 has shown potential for implementation as an anode material for lithium-ion batteries (LIBs), however, the significant volume expansion and dissolution of selenium pose major challenges. In this work, Bi2Se3 nanostructures are synthesized by physical vapor deposition directly on top of a single-wall carbon nanotube (SWCNT) network to fabricate a binder-free Bi2Se3@SWCNT anode materials with different Bi2Se3/SWCNT ratios. Nanostructuring the Bi2Se3 directly on the top of the SWCNT network provides a large accessible contact area and improves mechanical and electrical contact. The heterostructures exhibit capacity, that is beyond the theoretical of pristine Bi2Se3, which can be attributed to the binding of the Se to C, resulting in the resilience against the dissolution of Se, while providing additional electron transport pathways and increased capacitive contribution. A Bi2Se3@SWCNT anode with a mass ratio of (1:1) has the highest capacity in a half-cell after 100 cycles (523 mAh g-1 at 0.1 A g-1) and shows excellent capacity retention after 500 cycles at large current densities (2 A g-1 and 5 A g-1): 1080 mAh g-1 and 809 mAh g-1 respectively. In addition, in a full-cell system Bi2Se3@SWCNT (1:1) delivers high reversible capacity after 150 cycles (484 mAh g-1) at 0.4 A g- 1.