Nanoscale Kirkendall Effect Synthesis of Echinus-like SnO2@SnS2 Nanospheres as High Performance Anode Material for Lithium Ion Batteries

• The echinus-like SnO2@SnS2 shell–shell-structured nanospheres was prepared through a facile hydrothermal method based on nanoscale Kirkendall effect.
• The hierarchical and hollow composite structure has proved itself to be helpful to improve the cycle performance of lithium ion batteries.
• Exhibited high capacity of 548 mA h g−1 at a current density of 100 mA g−1 after 100 cycles.
• Exhibited excellent rate capability and reversible capacity of 870.5, 733.7, 626.4, 577.7, 551.8 and 443.4 mA h g−1 at the high rate of 0.1, 0.2, 0.5, 1, 2 and 5 C, respectively.

Crystalline echinus-like SnO2@SnS2 shell-shell-structured nanospheres (SSN) are fabricated by a hydrothermal method based on nanoscale Kirkendall Effect. Single crystal SnS2 nanorods with length of approximately 50 nm and width of approximately 8-15 nm are arranged regularly on the surface of the nanospheres. When the echinus-like SnO2@SnS2 SSN are used as anode materials for Li-ion batteries, the initial capacity is 1558 mA h g−1, and the reversible capacity after 100 cycles of the products is 548 mA h g−1. The SnO2@SnS2 nanocomposites also display excellent rate capability with a reversible capacity of 443.4 mA h g−1 even at the current rate of 5 C. The high electrochemical performance is attributed to the synergistic effect of the hierarchical hollow nanostructure: (1) fast ion diffusion and electron transport at electrode/electrolyte interface, (2) sufficient space to minimize the damage to the electrode caused by the volume expansion of tin-based materials during charge-discharge process. The encouraging experimental results suggest that the novel echinus-like hollow shell-shell structured nanospheres have great potential for practical applications of Li-ion batteries.