Electrospinning Synthesis of Ni°, Fe° Codoped Ultrafine-ZnFe2O4/C Nanofibers and Their Properties for Lithium Ion Storage

• Ultrafine ferrites/C nanofibers are synthesized by an electrospinning method.
• ZnFe2O4/Ni/Fe/C nanofibers exhibit an excellent performance of li-ion battery.
• Codoping with moderate Ni and Fe can greatly improve the conductivity.
• The amorphous carbon can relieve the stress arising from the volumetric expansion.
• 1D network can enhance the interaction between active materials and electrolyte.

This work discusses codoping moderate metal nanoparticles (Ni, Fe) on the ferrite/C composite nanofibers to improve the electronic conductivity. The ultrafine Ni0.5Zn0.5Fe2O4/Ni/C, ZnFe2O4/Ni/Fe/C, and ZnO/Ni/Fe/C nanofibers are synthesized by electrospinning and subsequent annealing at 450, 550 and 650 °C, respectively. Their growth mechanism, morphologies and lithium ion storage properties are investigated in detail. ZnFe2O4/Ni/Fe/C exhibits the best electrochemical performance. The composite shows an initial discharge capacity of 1316 mA h g−1 and manages to achieve a capacity of 793 mA h g−1 after 200 cycles at 100 mA g−1. A high capability of 450 mA h g−1 is still obtained when the current density increases to 1 A g−1. We also compare the lithium ion storage properties of pure ZnFe2O4, ZnFe2O4/C and ZnFe2O4/Ni/Fe/C to demonstrate the positive effect of codoping ferrites by Ni and Fe nanoparticles with amorphous carbon mixed.

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