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Experimental visualization of the diffusion pathway of sodium ions in the Na 3 [Ti 2 P 2 O 10 F] anode for sodium-ion battery

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ABSTRACT

Sodium-ion batteries have attracted considerable interest as an alternative to lithium-ion batteries for electric storage applications because of the low cost and natural abundance of sodium resources. The materials with an open framework are highly desired for Na-ion insertion/extraction. Here we report on the first visualization of the sodium-ion diffusion path in Na3[Ti2P2O10F] through high-temperature neutron powder diffraction experiments. The evolution of the Na-ion displacements of Na3[Ti2P2O10F] was investigated with high-temperature neutron diffraction (HTND) from room temperature to 600°C; difference Fourier maps were utilized to estimate the Na nuclear-density distribution. Temperature-driven Na displacements indicates that sodium-ion diffusion paths are established within the ab plane. As an anode for sodium-ion batteries, Na3[Ti2P2O10F] exhibits a reversible capacity of ~100 mAh g−1 with lower intercalation voltage. It also shows good cycling stability and rate capability, making it promising applications in sodium-ion batteries.

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Observed (crosses), calculated (line), and difference (bottom) neutron-diffraction patterns of the tetragonal Na3[Ti2P2O10F] at room temperature (a) and 600°C (b).
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f1: Observed (crosses), calculated (line), and difference (bottom) neutron-diffraction patterns of the tetragonal Na3[Ti2P2O10F] at room temperature (a) and 600°C (b).

Mentions: The structural refinement was performed from room-temperature (RT) neutron powder diffraction (NPD) data. As reported in the Ref. 33, Na3[Ti2P2O10F] with a tetragonal I4/mmm space group was considered as a starting structural model. The unit-cell parameters at RT are a = 6.41763(8) Å and c = 10.6636(2) Å, in good agreement with the literature33. In this model Ti atoms are placed at 4e (0, 0, z) positions, P at 4d (0, ½, 3/4), F at 2a (0, 0, 0), O1 at 4e, O2 at 16n (0, y, z) and Na at 8h (0, y, y) positions. Isotropic displacement factors were refined for all the atoms, excepting Na for which an anisotropic refinement was considered. Also the Na occupancy was refined; there is a slight deficiency (2.84(3) Na atoms per formula unit) with respect to the nominal value of 3. Figure 1a shows a good agreement between the observed and calculated NPD patterns. The refined structural parameters at RT are summarized in Table 1, while the main bond distances and bond valences are gathered in Table S1 in Supporting Information.


Experimental visualization of the diffusion pathway of sodium ions in the Na 3 [Ti 2 P 2 O 10 F] anode for sodium-ion battery
Observed (crosses), calculated (line), and difference (bottom) neutron-diffraction patterns of the tetragonal Na3[Ti2P2O10F] at room temperature (a) and 600°C (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5384114&req=5

f1: Observed (crosses), calculated (line), and difference (bottom) neutron-diffraction patterns of the tetragonal Na3[Ti2P2O10F] at room temperature (a) and 600°C (b).
Mentions: The structural refinement was performed from room-temperature (RT) neutron powder diffraction (NPD) data. As reported in the Ref. 33, Na3[Ti2P2O10F] with a tetragonal I4/mmm space group was considered as a starting structural model. The unit-cell parameters at RT are a = 6.41763(8) Å and c = 10.6636(2) Å, in good agreement with the literature33. In this model Ti atoms are placed at 4e (0, 0, z) positions, P at 4d (0, ½, 3/4), F at 2a (0, 0, 0), O1 at 4e, O2 at 16n (0, y, z) and Na at 8h (0, y, y) positions. Isotropic displacement factors were refined for all the atoms, excepting Na for which an anisotropic refinement was considered. Also the Na occupancy was refined; there is a slight deficiency (2.84(3) Na atoms per formula unit) with respect to the nominal value of 3. Figure 1a shows a good agreement between the observed and calculated NPD patterns. The refined structural parameters at RT are summarized in Table 1, while the main bond distances and bond valences are gathered in Table S1 in Supporting Information.

View Article: PubMed Central - PubMed

ABSTRACT

Sodium-ion batteries have attracted considerable interest as an alternative to lithium-ion batteries for electric storage applications because of the low cost and natural abundance of sodium resources. The materials with an open framework are highly desired for Na-ion insertion/extraction. Here we report on the first visualization of the sodium-ion diffusion path in Na3[Ti2P2O10F] through high-temperature neutron powder diffraction experiments. The evolution of the Na-ion displacements of Na3[Ti2P2O10F] was investigated with high-temperature neutron diffraction (HTND) from room temperature to 600°C; difference Fourier maps were utilized to estimate the Na nuclear-density distribution. Temperature-driven Na displacements indicates that sodium-ion diffusion paths are established within the ab plane. As an anode for sodium-ion batteries, Na3[Ti2P2O10F] exhibits a reversible capacity of ~100 mAh g−1 with lower intercalation voltage. It also shows good cycling stability and rate capability, making it promising applications in sodium-ion batteries.

No MeSH data available.


Related in: MedlinePlus