Graphene-encapsulated Cu/TiO2 nanotubes anode materials for lithium/sodium ion batteries

Abstract

Graphene-encapsulated Cu/TiO2 nanotubes (GE@Cu/TiO2) were synthesized by a facile electrochemical anodization process. The average diameter of TiO2 nanotubes is ∼60 nm with a wall thickness of ∼30 nm and Cu particles are randomlydistributed on TiO2 nanotubes and graphene sheets. The initial discharge capacity of GE@Cu/TiO2 is 398.6 mA h g−1 and its capacity retains 223 mA h g−1 at the current density of 200 mA g−1 after 50 cycles for lithium-ion batteries. Its initial discharge capacity is 129.3 mA h g−1 and the capacity retains 76.7 mA h g−1 at the current density of 50 mA g−1 after 50 cycles in sodium-ion batteries. Moreover, the reversible capacity and cycle stability of GE@Cu/TiO2 are the best among three samples due to the synergistic effect of TiO2, Cu and GE.