PVP-assisted synthesis of hollow Ni0.75Zn0.25Fe2O4 nanospheres for lithium-ion batteries

Hollow Ni0.75Zn0.25Fe2O4 nanospheres with a diameter of about 250-300 nm and thickness of 30-40 nm have been successfully fabricated through a PVP (polyvinylpyrrolidone)-assisted hydrothermal strategy. PVP plays an important role in the formation of hollow structure and a plausible formation mechanism of hollow Ni0.75Zn0.25Fe2O4 nanospheres is also proposed in this paper. The as-fabricated hollow Ni0.75Zn0.25Fe2O4 nanospheres display a good dispersibility and high specific surface area of 34.7 m2 g-1. Hollow Ni0.75Zn0.25Fe2O4 nanospheres also demonstrate satisfactory cycle life and rate performance when evaluated as a lithium ion battery negative electrode. Namely, after 120 cycles, the discharge specific capacity is 1321.3 mAh g-1 at 200 mA g-1, and the capacity retention rate is as high as 99.2%. Furthermore, the average discharge capacities are 1482.5, 1451.5, 1330.9, 1232.3, 1031.2 and 944.8 mAh g-1 under the current densities of 100, 200, 500, 1000, 2000 and 4000 mA g-1, respectively. The promising electrochemical performance of the hollow Ni0.75Zn0.25Fe2O4 nanosphere could be attributed to the unique hollow structure of nano-spheres, which offers a higher specific surface area and shorten transmission pathways of electrons and ions, buffering the volume expansion during the Li+ insertion/desorption process.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Hollow Ni0.75Zn0.25Fe2O4 nanospheres with PVP-assisted hydrothermal strategy were successfully fabricated and displayed good dispersibility and high specific surface area. The nanospheres also demonstrated satisfactory cycle life and rate performance as a lithium ion battery negative electrode.