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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

Na-ion diffusion in Na2Fe2(SO4)3.(a,b) Equi-value surface of the ΔBVS. The blue and light-blue surfaces are for ΔBVS=0.2 and 0.4, respectively. Inner side of the surface corresponds to accessible spaces for the Na ions. Green and yellow polyhedra are that of FeO6 and SO4, respectively. (c) Migration activation energy of Na+ ion calculated with DFT. Shown are the values (from left to right) for migrations along the c axis for the Na2 sites, between Na2 and Na1 sites, between Na1 and Na3 sites, and along the c axis for the Na3 sites. Calculations are done at low concentration of Na.
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f4: Na-ion diffusion in Na2Fe2(SO4)3.(a,b) Equi-value surface of the ΔBVS. The blue and light-blue surfaces are for ΔBVS=0.2 and 0.4, respectively. Inner side of the surface corresponds to accessible spaces for the Na ions. Green and yellow polyhedra are that of FeO6 and SO4, respectively. (c) Migration activation energy of Na+ ion calculated with DFT. Shown are the values (from left to right) for migrations along the c axis for the Na2 sites, between Na2 and Na1 sites, between Na1 and Na3 sites, and along the c axis for the Na3 sites. Calculations are done at low concentration of Na.

Mentions: Na2Fe2(SO4)3 turns out to be an ideal host structure for efficient and fast Na+ (de)insertion with unusually high Fe redox potential. To gain further insight on this suitable structure, bond valence (BV) method was used to evaluate the validity of the crystal structure as well as to elucidate possible Na diffusion paths by utilizing the soft-BV parameters2829. Difference of the BV sum from the ideal value (ΔBVS) provides a simple measure of positional suitability of mobile ions in solid frameworks30. Figure 4 shows a map of ΔBVS as equi-value surface. Inner side of the equi-value surface shows accessible spaces for Na+ in the [Fe2(SO4)3]2– framework. All the refined Na positions are consistent with the ΔBVS map where the maximum ΔBVS at Na positions are <0.2. Although the Na1 and the Na2 looks to have rather localized character in the present analysis, the Na3 site are clearly permeating along the [001] direction.


A 3.8-V earth-abundant sodium battery electrode.

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

Na-ion diffusion in Na2Fe2(SO4)3.(a,b) Equi-value surface of the ΔBVS. The blue and light-blue surfaces are for ΔBVS=0.2 and 0.4, respectively. Inner side of the surface corresponds to accessible spaces for the Na ions. Green and yellow polyhedra are that of FeO6 and SO4, respectively. (c) Migration activation energy of Na+ ion calculated with DFT. Shown are the values (from left to right) for migrations along the c axis for the Na2 sites, between Na2 and Na1 sites, between Na1 and Na3 sites, and along the c axis for the Na3 sites. Calculations are done at low concentration of Na.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Na-ion diffusion in Na2Fe2(SO4)3.(a,b) Equi-value surface of the ΔBVS. The blue and light-blue surfaces are for ΔBVS=0.2 and 0.4, respectively. Inner side of the surface corresponds to accessible spaces for the Na ions. Green and yellow polyhedra are that of FeO6 and SO4, respectively. (c) Migration activation energy of Na+ ion calculated with DFT. Shown are the values (from left to right) for migrations along the c axis for the Na2 sites, between Na2 and Na1 sites, between Na1 and Na3 sites, and along the c axis for the Na3 sites. Calculations are done at low concentration of Na.
Mentions: Na2Fe2(SO4)3 turns out to be an ideal host structure for efficient and fast Na+ (de)insertion with unusually high Fe redox potential. To gain further insight on this suitable structure, bond valence (BV) method was used to evaluate the validity of the crystal structure as well as to elucidate possible Na diffusion paths by utilizing the soft-BV parameters2829. Difference of the BV sum from the ideal value (ΔBVS) provides a simple measure of positional suitability of mobile ions in solid frameworks30. Figure 4 shows a map of ΔBVS as equi-value surface. Inner side of the equi-value surface shows accessible spaces for Na+ in the [Fe2(SO4)3]2– framework. All the refined Na positions are consistent with the ΔBVS map where the maximum ΔBVS at Na positions are <0.2. Although the Na1 and the Na2 looks to have rather localized character in the present analysis, the Na3 site are clearly permeating along the [001] direction.

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