SnO₂@C@Fe₃O₄ Sandwich-like Hollow Nanospheres for High-Performance Lithium-Ion Battery Anodes

Abstract

SnO2@C@Fe3O4 sandwich-like hollow nanospheres are rationally synthesized by the surface adsorption of Fe(II) and the subsequent growth of Fe3O4 on the SnO2@C hollow nanospheres. In the novel nanostructures, the SnO2 internal layer can supply an indurative and hollow framework, which can buffer the repetitive volume variation during cycles. The conductive carbon interlayer can apparently improve the electronic conductivity and efficiently avoid the aggregation of Fe3O4 and SnO2 nanoparticles. Fe3O4 nanoparticles on the surface can strengthen the walls of hollow nanospheres, which is beneficial to the structural integrity and thus improves the cycling stability. Moreover, the effects of the calcination temperature on the properties of anode nanomaterials are also investigated. The grain size of Fe3O4 nanoparticles on SnO2@C@Fe3O4 composites gradually expands with the increasing calcination temperature. The electrochemical properties of SnO2@C@Fe3O4 composites are optimized by bridging the respective merits of SnO2, C as well as Fe3O4 and adjusting the calcination temperature. It is found that the SnO2@C@Fe3O4 hollow nanospheres at 500 °C exhibit a high specific capacity (1468.1 mAh g–1) and an extraordinary cycling stability (1007.6 mAh g–1 after the 100th cycle). It is expected that this synthesis strategy can be further applied to the rational design of other nanomaterials for energy storage.