Progress of the Elements Doped NaFeO₂Cathode Materials for High Performance Sodium‐ion Batteries

Abstract

Layered metal oxide NaFeO 2 has been recognized is a promising cathode material for high-energy sodium-ion batteries (SIBs) due to its low cost and high capacity. However, its poor structural stability during the Na + insertion/extraction results in capacity degradation and a short cycle life. Elemental doping is a very promising method to improve its performance.Here, layered iron-based oxides (NaFeO 2 or NaFeMeO 2 [Me = manganese, nickel, and so on]) were doped with different elements (manganese, nickel, copper, fluorine, etc.) and their performance as cathode materials of SIBs are reviewed and analyzed. We found that synergistic doping with multiple cations can improve sodium storage performance. Moreover, anionic doping is also worth exploring to improve the crystal structure and the sodium storage of these materials.

Recent Advances on F-Doped Layered Transition Metal Oxides for Sodium Ion Batteries

“…As a result, the cations and Fco-doping materials are more effective at dramatically enhancing the whole performance than the single doped cations as demonstrated via many data comparisons. Since it was significantly proven that the F-doping had greater improvement for the performance of SIBs, the iron-doped layered oxide cathodes also gradually became popular [68]. This is because the weak interaction between layers and the hollow twodimensional space provides great convenience for the migration of Na + [11].…”

Band Gap Energy of Ion‐Doped Multiferroic NaFeO2 Nanoparticles

“…[ 1 ] The ferroelectric phase transition temperature is around 1,373 K. [ 1 ] β ‐NFO nanoparticles (NPs) with the orthorhombic crystal structure (space group Pn2 1 a) offer a direct band gap of 2.35 eV whereas the bulk value is smaller −2.06 eV. [ 2 ] The effect of ion doping (e.g., Ge, Si, Mn, Ni, Cu, Co, F on the Fe site) on different properties of β ‐NFO has been studied experimentally by Kuganathan et al, [ 3 ] Rahmawati et al, [ 4 ] and Zhao et al [ 5 ] Unfortunately, not many works exist considering the band gap energy of α ‐NFO which is also multiferroic. [ 6 ] At T N1 = 11 K, there appears a transition from the paramagnetic phase to a phase characterized by an incommensurate spin density wave (ICM1).…”

Unveiling the different physicochemical properties of M-doped β-NaFeO2 (where M = Ni or Cu) materials evaluated as CO2 sorbents: a combined experimental and theoretical analysis

“…[3][4][5] These features arise from the Fe 3+ /Fe 2+ redox couple, 6 the presence of unoccupied d-and s-orbitals in Fe and Na atoms, 7 respectively and iron's magnetic susceptibility, 3 among other aspects. These interesting properties have allowed the use of NaFeO 2 -based materials in different technological applications, such as sodium-ion batteries (SIBs), [8][9][10] magnetic biomedical devices [11][12][13] and CO 2 solid sorbents. [14][15][16] In all these areas, the sodium mobility in the NaFeO 2 crystalline structure is crucial for an adequate performance.…”

“…Within this frame, nickel and copper transition metals are considered suitable candidates due to their low cost and high availability, 26 along with some chemical similarities to iron (e.g., ionic radii), as these atoms typically adopt two oxidation states: Cu 2+ /Cu 3+ and Ni 2+ /Ni 3+ . 9,27 The doping process of layered sodium ferrites (a-NaFeO 2 ) has been widely explored in sodium-ion battery applications. [27][28][29] For instance, Li and co-workers improved the Na diffusion of these ferrites by doping the material with Mn, Co and Ni.…”

“…, ionic radii), as these atoms typically adopt two oxidation states: Cu 2+ /Cu 3+ and Ni 2+ /Ni 3+ . 9,27 The doping process of layered sodium ferrites (α-NaFeO 2 ) has been widely explored in sodium-ion battery applications. 27–29 For instance, Li and co-workers improved the Na diffusion of these ferrites by doping the material with Mn, Co and Ni.…”