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Unraveling the storage mechanism in organic carbonyl electrodes for sodium-ion batteries.

Wu X, Jin S, Zhang Z, Jiang L, Mu L, Hu YS, Li H, Chen X, Armand M, Chen L, Huang X - Sci Adv (2015)

Bottom Line: We take Na2C6H2O4 as an example to unravel the mechanism.It consists of alternating Na-O octahedral inorganic layer and π-stacked benzene organic layer in spatial separation, delivering a high reversible capacity and first coulombic efficiency.The experiment and calculation results reveal that the Na-O inorganic layer provides both Na(+) ion transport pathway and storage site, whereas the benzene organic layer provides electron transport pathway and redox center.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.

ABSTRACT
Organic carbonyl compounds represent a promising class of electrode materials for secondary batteries; however, the storage mechanism still remains unclear. We take Na2C6H2O4 as an example to unravel the mechanism. It consists of alternating Na-O octahedral inorganic layer and π-stacked benzene organic layer in spatial separation, delivering a high reversible capacity and first coulombic efficiency. The experiment and calculation results reveal that the Na-O inorganic layer provides both Na(+) ion transport pathway and storage site, whereas the benzene organic layer provides electron transport pathway and redox center. Our contribution provides a brand-new insight in understanding the storage mechanism in inorganic-organic layered host and opens up a new exciting direction for designing new materials for secondary batteries.

No MeSH data available.


Related in: MedlinePlus

Charge compensation mechanism.(A to C) Change in the electron density near the benzene ring in Fourier map obtained from the Rietveld refinement (A) Na2C6H2O4, (B) Na3C6H2O4, and (C) Na4C6H2O4. (D to F) DOS for (D) Na2C6H2O4, (E) Na3C6H2O4, and (F) Na4C6H2O4. The Fermi level is set to zero.
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Figure 7: Charge compensation mechanism.(A to C) Change in the electron density near the benzene ring in Fourier map obtained from the Rietveld refinement (A) Na2C6H2O4, (B) Na3C6H2O4, and (C) Na4C6H2O4. (D to F) DOS for (D) Na2C6H2O4, (E) Na3C6H2O4, and (F) Na4C6H2O4. The Fermi level is set to zero.

Mentions: On the basis of the resolved structure of the three compounds, the electron and ion transport mechanisms have been investigated via DFT calculations. The change of the electron density near the benzene ring before and after sodium insertion, and the corresponding density of states (DOS) are shown in Fig. 7. It is shown that after sodium insertion, the injected electrons delocalize on the whole benzene ring rather than localizing on carbon-oxygen bonds. The DOS results in Fig. 7 (D to F) also indicate that the injected electrons will occupy the empty orbitals of C2p and O2p. However, variations in the Bader charge values of C2 and C3 atoms are much larger than those of O atoms after sodium insertion, implying that the injected electrons mainly localize on the C2 and C3 atoms (Table 2). These results indicate that in the crystalline state, the redox center is a benzene ring rather than a carbon-oxygen double bond in this quinonyl compound. Benzene rings function similarly to transitional metal in inorganic layered oxides to receive electron.


Unraveling the storage mechanism in organic carbonyl electrodes for sodium-ion batteries.

Wu X, Jin S, Zhang Z, Jiang L, Mu L, Hu YS, Li H, Chen X, Armand M, Chen L, Huang X - Sci Adv (2015)

Charge compensation mechanism.(A to C) Change in the electron density near the benzene ring in Fourier map obtained from the Rietveld refinement (A) Na2C6H2O4, (B) Na3C6H2O4, and (C) Na4C6H2O4. (D to F) DOS for (D) Na2C6H2O4, (E) Na3C6H2O4, and (F) Na4C6H2O4. The Fermi level is set to zero.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643786&req=5

Figure 7: Charge compensation mechanism.(A to C) Change in the electron density near the benzene ring in Fourier map obtained from the Rietveld refinement (A) Na2C6H2O4, (B) Na3C6H2O4, and (C) Na4C6H2O4. (D to F) DOS for (D) Na2C6H2O4, (E) Na3C6H2O4, and (F) Na4C6H2O4. The Fermi level is set to zero.
Mentions: On the basis of the resolved structure of the three compounds, the electron and ion transport mechanisms have been investigated via DFT calculations. The change of the electron density near the benzene ring before and after sodium insertion, and the corresponding density of states (DOS) are shown in Fig. 7. It is shown that after sodium insertion, the injected electrons delocalize on the whole benzene ring rather than localizing on carbon-oxygen bonds. The DOS results in Fig. 7 (D to F) also indicate that the injected electrons will occupy the empty orbitals of C2p and O2p. However, variations in the Bader charge values of C2 and C3 atoms are much larger than those of O atoms after sodium insertion, implying that the injected electrons mainly localize on the C2 and C3 atoms (Table 2). These results indicate that in the crystalline state, the redox center is a benzene ring rather than a carbon-oxygen double bond in this quinonyl compound. Benzene rings function similarly to transitional metal in inorganic layered oxides to receive electron.

Bottom Line: We take Na2C6H2O4 as an example to unravel the mechanism.It consists of alternating Na-O octahedral inorganic layer and π-stacked benzene organic layer in spatial separation, delivering a high reversible capacity and first coulombic efficiency.The experiment and calculation results reveal that the Na-O inorganic layer provides both Na(+) ion transport pathway and storage site, whereas the benzene organic layer provides electron transport pathway and redox center.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.

ABSTRACT
Organic carbonyl compounds represent a promising class of electrode materials for secondary batteries; however, the storage mechanism still remains unclear. We take Na2C6H2O4 as an example to unravel the mechanism. It consists of alternating Na-O octahedral inorganic layer and π-stacked benzene organic layer in spatial separation, delivering a high reversible capacity and first coulombic efficiency. The experiment and calculation results reveal that the Na-O inorganic layer provides both Na(+) ion transport pathway and storage site, whereas the benzene organic layer provides electron transport pathway and redox center. Our contribution provides a brand-new insight in understanding the storage mechanism in inorganic-organic layered host and opens up a new exciting direction for designing new materials for secondary batteries.

No MeSH data available.


Related in: MedlinePlus