Rambutan-like Ni0.5Zn0.5Fe2O4 nanospheres with tunable N-doped carbon shell as anode materials for high performance lithium-ion batteries

Multi-metal oxides have abroad application prospects as anode materials in lithium-ion batteries (LIBs) due to their adjustable chemical composition and plentiful active sites. In this study, rambutan-like Ni0.5Zn0.5Fe2O4 nanosphere are prepared by incorporating Zn into NiFe2O4, using a self-templating solvothermal technique. Then, Ni0.5Zn0.5Fe2O4@ N-doped carbon (NC) shell materials with different thickness of NC shell are obtained via coating different amount of dopamine followed by carbonization. As a LIBs anode material, the effects of NC shell thickness on electrochemical properties are discussed, and the Ni0.5Zn0.5Fe2O4@NC with 15 nm NC shell delivers 953.6 mA h g−1 specific capacity after 400 cycles at a current density of 1 A g−1, while the reversible capacity reaches 1124.3 mA h g−1 at the current of 0.1 A g−1. These results confirm that the appropriate NC shell thickness can effectively buffer the volume change and improve the electronic conductivity, accordingly improve the capacity and cycle stability of the electrode material. Furthermore, LiCoO2//Ni0.5Zn0.5Fe2O4@NC lithium-ion full cells are successfully assembled, and the electrochemical evaluation results demonstrate that they exhibit excellent lithium storage performance and promising application prospect.