Zinc Ferrite Nanorod‐Assembled Mesoporous Microspheres as Advanced Anode Materials for Sodium‐Ion Batteries

Abstract

Mesoporous zinc ferrite (ZnFe2O4) microspheres assembled by nanorods are fabricated through a facile hydrothermal approach, followed by a calcination strategy. The fabricated mesoporous ZnFe2O4 has a diameter of approximately 500–800 nm with a high surface area of 91.6 m2 g−1. The utilization of the microspheres that serve as anode materials for sodium‐ion batteries is studied for the first time. The electrochemical results demonstrate that the ZnFe2O4 anode experiences a series of conversion and alloying reactions for reversible sodium storage and exhibits high sodium storage capacity and excellent stability. It exhibits a reversible capacity as high as 350 mAh g−1 after 300 cycles at 100 mA g−1, which is superior to other reported ZnO and ZnMxOy (M = Co, Sn, Ge) electrodes. The existence of the mesoporous structure is responsible for the excellent electrochemical properties of the microspheres, which not only enhances the electrochemical kinetics but also offers additional space to alleviate the strain associated with sodiation/desodiation.

Sodium insertion/extraction investigations into zinc ferrite nanospheres as a high performance anode material

“…Up till now, according to our knowledge, only a few reports are presented for ZnFe 2 O 4 as electrode material for the development of SIBs. 23 …”

Wet Chemical Synthesis of Cubic Spinel Ferrites: A Review Addressing Phase Formation Behavior and Nanostructuring

“…112 Ma et al have reported the synthesis of ZnFe 2 O 4 nanorodassembled mesoporous microspheres by the solvothermal route. 62 Zinc acetate and ferric nitrate were dissolved in a mixed solution of isopropanol and glycerol, followed by continuous stirring. After keeping the solution in an autoclave for 12 h at 180 °C, it was allowed to cool to 25 °C.…”

“…The inset shows the corresponding FFT image. Reproduced with permission from ref . Copyright 2019 WILEY-VCH Verlag GmbH & Co. KGaA.…”

“…The spinel ferrites exhibit a face-centered cubic close-packed sublattice composed of 32 oxygen anions with 8 divalent and 16 trivalent metal cations (Fe 3+ ) filling up the tetrahedral and octahedral interstices (Figure 3). 25,61,62 Such an arrangement of the ions ensures the electroneutrality of the system, resulting in the general chemical formula of MFe 2 O 4 (where M is a divalent metal cation, for example, Co, Ni, Cu, Zn, Mn, Fe, and Mg). 25 Depending on the site occupancy of the metal ions, the ferrite crystal system can have three different structures: (i) normal spinel, where M 2+ ions are filled in the 8 sites out of the 64 tetrahedral sites available and Fe 3+ ions occupy 16 of the 32 octahedral sites available; (ii) inverse spinel, where M 2+ cations are located in 8 octahedral sites and the Fe 3+ cations are distributed in same proportion between 8 tetrahedral and 8 octahedral sites; and (iii) mixed spinel, where both M 2+ and Fe 3+ are randomly distributed within the tetrahedral and octahedral sites.…”

“…(b) Crystal structure of spinel Zinc ferrite. Reproduced with permission from ref . Copyright 2019 Wiley-VCH Verlag GmbH & Co. KGaA.…”