Nanosheet assembled hollow ZnFe2O4 microsphere as anode for lithium-ion batteries

Highlights: • Hollow ZnFe₂O₄ microspheres are obtained by simple hydrothermal and calcined method. • Hollow ZnFe₂O₄ microspheres are comprised of nanosheets as the original building blocks. • The reversible capacity of 1200 mAh g⁻¹ can be obtained at 100 mA g⁻¹ over 120 cycles. • The discharge can still retain 533 mAh g⁻¹ after 250 cycles at a high charge rate of 500 mA g⁻¹. Nanosheet assembled hollow ZnFe₂O₄ microspheres have been successfully prepared using a general hydrothermal method together with post-annealed process. As the anode electrode of a lithium-ion battery, the high discharge capacity of 1200 mAh g⁻¹ can be obtained after 120 cycles at a current density of 100 mA g⁻¹. It is noted that the cell capacity still remains at 533 mAh g⁻¹ after 250 cycles at a high current density of 500 mA g⁻¹. The prominent electrochemical performance is related to the unique mesoporous hollow structure, which increases the contact areas of the electrolyte and active material resulting in well electrolyte permeation as well as providing abundant void space to suppress the volume expansion during the lithium-ion insertion and extraction process.