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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