Hierarchical hybrid ZnFe2O4 nanoparticles/reduced graphene oxide composite with long-term and high-rate performance for lithium ion batteries

Highlights: • A fast low-temperature refluxing strategy is developed to prepare hierarchical hybrid ZnFe₂O₄ NPs/rGO composite. • The synergistic effect of mesoporous ZnFe₂O₄ NPs and conductive rGO substrate is beneficial to the electrochemical process. • A high reversible capacity of 1106.7 mAh g⁻¹ can be stably maintained even after 400 cycles at 200 mA g⁻¹. Hierarchical hybrid nanostructure of mesoporous ZnFe₂O₄ nanoparticles anchored on reduced graphene oxide (ZnFe₂O₄ NPs/rGO) has been successfully developed in this research via a fast low-temperature refluxing method and a subsequent-annealing treatment in N₂. The unique mesoporous network structures of ZnFe₂O₄ NPs supported by flexible rGO sheets offer sufficient electrode-electrolyte contact, shorten Li⁺ ions diffusion distance, and thus greatly facilitate the electrochemical reactions via accommodating the volume change efficiently during cycling. Meanwhile, the conductive rGO matrix in the hybrid composite also ensures rapid electron transport to avoid the serve pulverization. Just based on such beneficial synergistic effect, the well-designed hierarchical hybrid ZnFe₂O₄ NPs/rGO composites present excellent lithium storage performance with high reversible discharge capacity, long-term cycle stability and superb high-rate capability when used as an anode for LIBs. A stable discharge capacity of as high as about 1106.7 mAh g⁻¹ is well maintained even after 400 cycles at the current density of 200 mA g⁻¹. We think this facile strategy could be further extended to the fabrication of other graphene-based electrodes for advanced energy applications.