Octahedral core–shell cuprous oxide/carbon with enhanced electrochemical activity and stability as anode for lithium ion batteries

• Core–shell octahedral Cu2O/C is prepared by a one-step method.
• Carbon shell is amorphous and uniformly decorated at the Cu2O octahedral core.
• Core–shell Cu2O/C exhibits markedly enhanced capability and reversibility.
• Carbon shell provides fast ion/electron transfer channel.
• Core–shell structure is stable during cycling.

Core–shell Cu2O/C octahedrons are synthesized by a simple hydrothermal method with the help of carbonization of glucose, which reduces Cu(II) to Cu(I) at low temperature and further forms carbon shell coating at high temperature. SEM and TEM images indicate that the carbon shell is amorphous with thickness of ∼20 nm wrapping the Cu2O octahedral core perfectly. As anode of lithium ion batteries, the core–shell Cu2O/C composite exhibits high and stable columbic efficiency (98%) as well as a reversible capacity of 400 mAh g−1 after 80 cycles. The improved electrochemical performance is attributed to the novel core–shell structure, in which the carbon shell reduces the electrode polarization and promotes the charge transfer at active material/electrolyte interface, and also acts as a stabilizer to keep the octahedral structure integrity during discharge–charge processes.

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