Nanoscale localized growth of SnSb for general-purpose high performance alkali (Li, Na, K) ion storage

In this paper, we have successfully encapsulated SnSb alloy nanoparticles into the space of N-doped carbon nanotubes and carbon shells (NC@SnSb@NC) like a three-dimensional (3D) corn-like structure via a unique method, showing excellent electrochemical storage performance for alkali metal-ion batteries. Here, Sn and Sb can be alloyed with alkali metal ions (Li⁺/Na⁺/K⁺) at different potentials, which can serve as a buffer substrate for each other and inhibit the pulverization of active materials. Pyridine N and pyrrole N in the composite can produce abundant external defects and active sites, which are conducive to accelerating the transmission of alkali metal ions (Li⁺/Na⁺/K⁺). The available space derived from the carbon nanotubes and carbon shells also can effectively alleviate volume change, making high mechanical flexibility and keeping the whole electrode integrity during charge and discharge process. In-situ, ex-situ characterizations and density functional theory (DFT) calculations collectively confirm the excellent reversibility of alkali metal ions storage and fast electrochemical kinetics of the 3D NC@SnSb@NC composite. Due to the outstanding electrochemical properties, the NC@SnSb@NC composite can be of great significance for practical design and application in next-generation alkali metal-ion batteries.