Direct fabrication of double-rough chestnut-like multifunctional Sn@C composites on copper foil: lotus effect and lithium ion storage properties

This paper reports the fabrication of a new, double-rough chestnut-like Sn@C composite in the form of mesospheres with nanohairs directly on a copper surface by a simple and scalable procedure. The hierarchical order in the nanostructure and the composition of the nanocomposite impart at least two functional properties: the lotus effect and reversible storage of lithium ions. The nanohairs of carbon nanotube-encapsulated metallic tin; and the underlying core of carbon-tin mesospheres with rough exterior; give rise to nanoscale and mesoscale roughness not unlike the double-rough surface of a lotus leave (nanohairs on microbumps). Subsequently the modified copper surface is superhydrophobic just like the lotus leaves. On the other hand the ability to directly deposit lithium-active storage compounds (Sn, C) on a current conductor (Cu) has also resulted in an electrode immediately usable as a lithium ion battery anode without additional processing. Indeed electrochemical measurements have shown quite satisfying properties for lithium ion battery applications.