Highly porous reticular tin–cobalt oxide composite thin film anodes for lithium ion batteries

A tin–cobalt oxide film with a 3-dimensional (3D) reticular structure has been prepared by electrostatic spray deposition (ESD). X-Ray diffraction (XRD) and transmission electron microscopy (TEM) make it clear that the film is amorphous. X-Ray photoemission spectroscopy (XPS) indicates that the 3D grid is composed of SnO2 and CoO. As an anode for the lithium ion battery, the film has 1240.2 mAh/g of initial discharge capacity, shows a gradually increasing capacity after the first cycle, and has 845 mAh/g of discharge capacity up to the 50th cycle. The high porosity of the 3D reticular structure can provide more reaction sites on the electrode surface and accommodate volume variation of Sn particles during Li alloying–dealloying. The CoO in the complex composite film plays an important role, allowing the formation of a polymeric gel-like film to improve its electrochemical performance, preventing Sn aggregation during charging and discharging. Such a composite film can be used as an anode for lithium ion batteries with higher energy densities.