A novel hollowed CoO-in-CoSnO₃ nanostructure with enhanced lithium storage capabilities

The search for well-defined porous/hollowed metal oxide nanocomposites for high performance energy storage is promising. Herein, atomic layer deposition (ALD) has been utilized for the construction of a novel hollowed wire-in-tube nanostructure of CoO-in-CoSnO₃, for which Co₂(OH)₂CO₃ nanowires are first obtained by a hydrothermal method and then deposited with ALD SnO₂. After a proper thermal treatment, a CoO wire-void-CoSnO₃ tube was formed with the decomposition of Co₂(OH)₂CO₃ and its simultaneous reaction with the outer SnO₂ layer. In this unique wire-in-tube structure, both CoO and CoSnO₃ are promising materials for lithium ion battery anodes with high theoretical capacities, and the porous + hollow feature is essential for better electrode/electrolyte contact, shorter ion diffusion path and better structure stability. After a further facile carbon coating, the hollowed wire-in-tube structure delivered an improved capacity of 1162.1 mA h g^-1, which is much higher than that of the bare CoO nanowire. Enhanced rate capability and cycling stability have also been demonstrated with the structure, showing its promising application for the anode material of lithium ion battery. The work also demonstrated an effective way of using ALD SnO₂ for electrochemical energy storage that ALD SnO₂ plays a key role in the structure formation and also serves as both active material and surface coating.