Sb nanoparticles encapsulated in N-doped carbon nanotubes as freestanding anodes for high-performance lithium and potassium ion batteries

Sb-based materials with high specific capacity have targeted as an alternative anode material for alkali metal ion batteries. Herein, Sb nanoparticles embedded in hollow porous N-doped carbon nanotubes (Sb@N-C nanotubes) are used as freestanding anode for Li-ion batteries (LIBs) and K-ion batteries (PIBs). The Sb@N-C nanotubes demonstrate exceptional reversible capacity of 643 mAh.g(-1) at 0.1 A.g(-1) with long cycle stability, as well as outstanding rate performance (219.6 mAh.g(-1) at 10 A.g(-1)) in LIBs. As the anode material of PIBs, they reveal impressive capacity of 325.4 mAh.g(-1) at 0.1 A.g(-1). The superior electrochemical properties mainly originate from the novel structure. To be specific, the obtained 3D connected network allows for quick ion and electron migration, and prevents the aggregation of Sb nanoparticles. The hollow porous nanotubes can not only accommodate the volume expansion of Sb nanoparticles during cycling, but also facilitate the infiltration of the electrolyte and reduce the ion diffusion length. This work provides a new insight for designing advanced Sb-based anodes for alkali metal ion batteries.