Hydrothermal Synthesis of SnO2 Embedded MoO3-x Nanocomposites and Their Synergistic Effects on Lithium Storage

Abstract We demonstrate a facile hydrothermal synthesis of SnO 2 /MoO 3-x nanocomposites with ultrafine SnO 2 crystallites uniformly embedded into an amorphous MoO 3-x matrix, which demonstrate superior electrochemical performance as anodes for lithium ion batteries, including long-term cycling stability (953 mA h/g after 100 cycles at 200 mA/g), high rate capability (668.0 mA h/g after 1000 cycles at 1000 mA/g) and high initial Coulombic efficiency (81.3% at 200 mA/g). Synergistic effects of the both components SnO 2 and MoO 3-x on the lithium storage are revealed by electrochemical characterization and supported by TEM and XPS analysis performed at the different discharge/charge states of the respective electrodes. SnO 2 nanocrystallites confined within the amorphous MoO 3-x matrix efficiently buffer the volume changes of Li-Sn alloying-dealloying upon cycling, while the metallic Mo in situ generated by a conversion reaction of MoO 3-x promotes the reversible reaction SnO 2  + Li +  ↔ Sn + Li 2 O. In addition, the amorphous MoO 3-x with bulk or surface defects allows for a better lithium insertion and thus enhanced capacity.