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A 3.8-V earth-abundant sodium battery electrode.

Barpanda P, Oyama G, Nishimura S, Chung SC, Yamada A - Nat Commun (2014)

Bottom Line: Rechargeable lithium batteries have ushered the wireless revolution over last two decades and are now matured to enable green automobiles.However, their performance is limited owing to low operating voltage and sluggish kinetics.Here we report a hitherto-unknown material with entirely new composition and structure with the first alluaudite-type sulphate framework, Na2Fe2(SO4)3, registering the highest-ever Fe(3+)/Fe(2+) redox potential at 3.8 V (versus Na, and hence 4.1 V versus Li) along with fast rate kinetics.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan [2] Unit of Element Strategy Initiative for Catalysts and Batteries, ESICB, Kyoto University, Kyoto 615-8510, Japan [3] Materials Research Center, Indian Institute of Science, Bangalore 560012, India [4].

ABSTRACT
Rechargeable lithium batteries have ushered the wireless revolution over last two decades and are now matured to enable green automobiles. However, the growing concern on scarcity and large-scale applications of lithium resources have steered effort to realize sustainable sodium-ion batteries, Na and Fe being abundant and low-cost charge carrier and redox centre, respectively. However, their performance is limited owing to low operating voltage and sluggish kinetics. Here we report a hitherto-unknown material with entirely new composition and structure with the first alluaudite-type sulphate framework, Na2Fe2(SO4)3, registering the highest-ever Fe(3+)/Fe(2+) redox potential at 3.8 V (versus Na, and hence 4.1 V versus Li) along with fast rate kinetics. Rare-metal-free Na-ion rechargeable battery system compatible with the present Li-ion battery is now in realistic scope without sacrificing high energy density and high power, and paves way for discovery of new earth-abundant sustainable cathodes for large-scale batteries.

No MeSH data available.


Related in: MedlinePlus

XRD pattern of Na2Fe2(SO4)3.Rietveld refinement pattern of powder XRD data for Na2Fe2(SO4)3. Experimental data and calculated profile and their difference are shown as red crosses and black and purple solid lines, respectively. The theoretical Bragg positions are shown with green ticks. Trace amount (about 4 wt%) of bata-FeSO4 as an impurity was included in the analysis, as indicated by yellow ticks. (Inset) Room temperature Mössbauer spectrum of pristine Na2Fe2(SO4)3 shows the existence of two distinctive Fe(II) sites in 1:1 ratio (red and blue lines).
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f1: XRD pattern of Na2Fe2(SO4)3.Rietveld refinement pattern of powder XRD data for Na2Fe2(SO4)3. Experimental data and calculated profile and their difference are shown as red crosses and black and purple solid lines, respectively. The theoretical Bragg positions are shown with green ticks. Trace amount (about 4 wt%) of bata-FeSO4 as an impurity was included in the analysis, as indicated by yellow ticks. (Inset) Room temperature Mössbauer spectrum of pristine Na2Fe2(SO4)3 shows the existence of two distinctive Fe(II) sites in 1:1 ratio (red and blue lines).

Mentions: Unlike the oxides and various polyanions (BO33−, PO43− and SiO44−) compounds, the SO42− containing systems are acutely prone to thermal decomposition above ~400 °C (leading to SO2 gas evolution). In addition, inherent dissolution of SO42− in water makes it unstable in aqueous media. It rules out conventional high-temperature solid-state and aqueous solution-based synthetic routes. Thus, we used low-temperature (Tr ≤350 °C) solid-state methods to obtain Na2Fe2(SO4)3 target compound. The unknown crystal structure of this new cathode material was determined by synchrotron powder X-ray diffraction (XRD) (Fig. 1). Rietveld refinement and Mössbauer data (Fig. 1, inset) confirm trace amount of Fe(III) impurity phase(s). Mössbauer spectrum of the pristine material, consisting only Fe(II) species, could be fitted with two doublets having 1:1 intensity ratio, which can be assigned to two distinct crystallographic sites, Fe(1) and Fe(2). All the Bragg reflections were indexed in a monoclinic lattice assuming P21/c (No. 14) symmetry with lattice parameters a=11.46964(8) Å, b=12.77002(9) Å, c=6.51179(5) Å, β=95.2742(4)° and V=949.73(1) Å3. Although non-stoichiometry was to be considered, the fitting was satisfactory (Rwp=4.87%, Rp=3.94%, RBragg=1.58% and Goodness of fit (GoF)=1.74). Trace amount (about 4 wt%) of bata-FeSO4 as an impurity was included in the analysis. The crystallographic data are summarized in Supplementary Tables 1 and 2. Indexing and analysis adopting alternative C2/c symmetry with one Fe site was also possible with slight increase in RBragg as summarized in Supplementary Tables 3 and 4, indicating that local environments of two Fe sites are quite similar. Although P21/c symmetry seems more suitable in the present analysis, further systematic approach by electron diffraction and/or single-crystal XRD would be necessary for the firm conclusion on P21/c versus C2/c.


A 3.8-V earth-abundant sodium battery electrode.

Barpanda P, Oyama G, Nishimura S, Chung SC, Yamada A - Nat Commun (2014)

XRD pattern of Na2Fe2(SO4)3.Rietveld refinement pattern of powder XRD data for Na2Fe2(SO4)3. Experimental data and calculated profile and their difference are shown as red crosses and black and purple solid lines, respectively. The theoretical Bragg positions are shown with green ticks. Trace amount (about 4 wt%) of bata-FeSO4 as an impurity was included in the analysis, as indicated by yellow ticks. (Inset) Room temperature Mössbauer spectrum of pristine Na2Fe2(SO4)3 shows the existence of two distinctive Fe(II) sites in 1:1 ratio (red and blue lines).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109020&req=5

f1: XRD pattern of Na2Fe2(SO4)3.Rietveld refinement pattern of powder XRD data for Na2Fe2(SO4)3. Experimental data and calculated profile and their difference are shown as red crosses and black and purple solid lines, respectively. The theoretical Bragg positions are shown with green ticks. Trace amount (about 4 wt%) of bata-FeSO4 as an impurity was included in the analysis, as indicated by yellow ticks. (Inset) Room temperature Mössbauer spectrum of pristine Na2Fe2(SO4)3 shows the existence of two distinctive Fe(II) sites in 1:1 ratio (red and blue lines).
Mentions: Unlike the oxides and various polyanions (BO33−, PO43− and SiO44−) compounds, the SO42− containing systems are acutely prone to thermal decomposition above ~400 °C (leading to SO2 gas evolution). In addition, inherent dissolution of SO42− in water makes it unstable in aqueous media. It rules out conventional high-temperature solid-state and aqueous solution-based synthetic routes. Thus, we used low-temperature (Tr ≤350 °C) solid-state methods to obtain Na2Fe2(SO4)3 target compound. The unknown crystal structure of this new cathode material was determined by synchrotron powder X-ray diffraction (XRD) (Fig. 1). Rietveld refinement and Mössbauer data (Fig. 1, inset) confirm trace amount of Fe(III) impurity phase(s). Mössbauer spectrum of the pristine material, consisting only Fe(II) species, could be fitted with two doublets having 1:1 intensity ratio, which can be assigned to two distinct crystallographic sites, Fe(1) and Fe(2). All the Bragg reflections were indexed in a monoclinic lattice assuming P21/c (No. 14) symmetry with lattice parameters a=11.46964(8) Å, b=12.77002(9) Å, c=6.51179(5) Å, β=95.2742(4)° and V=949.73(1) Å3. Although non-stoichiometry was to be considered, the fitting was satisfactory (Rwp=4.87%, Rp=3.94%, RBragg=1.58% and Goodness of fit (GoF)=1.74). Trace amount (about 4 wt%) of bata-FeSO4 as an impurity was included in the analysis. The crystallographic data are summarized in Supplementary Tables 1 and 2. Indexing and analysis adopting alternative C2/c symmetry with one Fe site was also possible with slight increase in RBragg as summarized in Supplementary Tables 3 and 4, indicating that local environments of two Fe sites are quite similar. Although P21/c symmetry seems more suitable in the present analysis, further systematic approach by electron diffraction and/or single-crystal XRD would be necessary for the firm conclusion on P21/c versus C2/c.

Bottom Line: Rechargeable lithium batteries have ushered the wireless revolution over last two decades and are now matured to enable green automobiles.However, their performance is limited owing to low operating voltage and sluggish kinetics.Here we report a hitherto-unknown material with entirely new composition and structure with the first alluaudite-type sulphate framework, Na2Fe2(SO4)3, registering the highest-ever Fe(3+)/Fe(2+) redox potential at 3.8 V (versus Na, and hence 4.1 V versus Li) along with fast rate kinetics.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan [2] Unit of Element Strategy Initiative for Catalysts and Batteries, ESICB, Kyoto University, Kyoto 615-8510, Japan [3] Materials Research Center, Indian Institute of Science, Bangalore 560012, India [4].

ABSTRACT
Rechargeable lithium batteries have ushered the wireless revolution over last two decades and are now matured to enable green automobiles. However, the growing concern on scarcity and large-scale applications of lithium resources have steered effort to realize sustainable sodium-ion batteries, Na and Fe being abundant and low-cost charge carrier and redox centre, respectively. However, their performance is limited owing to low operating voltage and sluggish kinetics. Here we report a hitherto-unknown material with entirely new composition and structure with the first alluaudite-type sulphate framework, Na2Fe2(SO4)3, registering the highest-ever Fe(3+)/Fe(2+) redox potential at 3.8 V (versus Na, and hence 4.1 V versus Li) along with fast rate kinetics. Rare-metal-free Na-ion rechargeable battery system compatible with the present Li-ion battery is now in realistic scope without sacrificing high energy density and high power, and paves way for discovery of new earth-abundant sustainable cathodes for large-scale batteries.

No MeSH data available.


Related in: MedlinePlus