One-Pot Template-Free Cross-Linking Synthesis of SiOx-SnO2@C Hollow Spheres as a High Volumetric Capacity Anode for Lithium-Ion Batteries

Porous SiOx anodes for Li-ion batteries with a high volumetric energy density are desired. Herein, carbon-coated SiOx-SnO2 hollow spheres are prepared by facile one-pot high-temperature annealing without using any template. During the process, SiOx is obtained through Sn reduction with the assistance of C. In the composite, the SiOx hollow spheres have a thin wall, the small SnO2 particles are uniformly imbedded in the sphere wall, and the SiOx-SnO2 hollow spheres are coated by cross-linked carbon. As an anode, the composite has a large volumetric capacity (1339 mAh cm(-3) at 0.1 A g(-1)), a high gravimetric capacity (1030 mAh g(-1) at 0.1 A g(-1)), and a good cyclic stability (after 100 cycles, 90% capacity is retained compared with that of the second cycle at 0.5 A g(-1)). The high capacity and good cycle stability result from the superior structure of the composite. Furthermore, the thin wall of the sphere can timely release a large expanded volume during lithiation, and the conformal carbon also provides a framework to maintain the structural integrity and facilitate the formation of a stable solid-electrolyte interface.