Atomic Welded Dual-Wall Hollow Nanospheres for Three-in-One Hybrid Storage Mechanism of Alkali Metal Ion Batteries.

The rational design of hierarchical hollow nanomaterials is of critical significance in energy storage materials. Herein, dual-wall hollow nanospheres (DWHNS) Sn/MoS2@C are constructed by in situ confined growth and interface engineering. The inner hollow spheres of Sn/MoS2 are formed by atomic soldering MoS2 nanosheets with liquid Sn at high temperature. The formation mechanism of the hierarchical structure is explored by the morphology evolutions at different temperatures. The DWHNS Sn/MoS2@C manifest abundant inner space and high specific surface area, which provides more support sites for Li+/Na+/K+ storage and alleviates the volume effect of tin-based electrode materials to a certain extent. The composite material manifests an outstanding specific capacity and satisfactory reversibility of lithium ion batteries (∼931 mAh g-1 at 1 A g-1 after 500 cycles), sodium ion batteries (∼432 mAh g-1 at 1 A g-1 after 400 cycles), and potassium ion batteries (∼226 mAh g-1 at 1 A g-1 after 300 cycles). Additionally, the morphology evolution and mechanism analysis of DWHNS Sn/MoS2@C in alkali metal ion batteries are verified by ex situ measurement, which confirms the three-in-one hybrid storage mechanism, i.e., intercalation reaction of carbon shells, conversion reaction of MoS2, and alloying reaction of tin.