Enhanced Electrochemical Performance of Zn-Doped Fe3O4 with Carbon Coating

• Zn-doped Fe3O4 with carbon coating achieves a reversible capacity of 713.6 mAh g−1.
• Zn-doped Fe3O4 exhibits superior rate performances.
• Appropriate Zn-doping improves the electronic and ionic conductivity.
• Nitrogen-doped carbon coating is beneficial to electrochemical performance.

Zn-doped Fe3O4 particles with carbon coating are prepared by combining a co-precipitation method with an efficient carbonization process using pyrrole as carbon source. The Zn/Fe molar ratio is controlled by adjusting the addition amount of Zn and Fe precursors. Among the carbon-coated products, the sample with a Zn/Fe molar ratio of 0.05:1.95 achieves a reversible capacity of 713.6 mAh g−1 after 60 cycles at a current density of 100 mA g−1 and the capacities of 670.9, 625.0, 599.1, 566.2, 454.2, and 223.3 mAh g−1 at 100, 200, 400, 800, 1600, and 3200 mA g−1, respectively. The enhanced electrochemical performance is attributed to the improved electronic conductivity and Li-ion diffusion kinetics resulted from the Zn-doping in Fe3O4 and the nitrogen-doped carbon coating for buffering the volume change and improving the electronic conductivity.