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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

Crystal structure of Na2Fe2(SO4)3.(a) The structure of Na2Fe2(SO4)3 projected along the c axis; and (b) local environment of two independent Fe sites. Green octahedra, yellow tetrahedra and blue spheres show FeO6, SO4 and Na, respectively. Fe ions occupy two kinds of crystallographic sites that have distinctive octahedral geometries. Each FeO6 octahedra share an edge with the crystallographically equivalent octahedra and form Fe2O10 dimers. The SO42− anions interconnect these dimers so as to build up a three-dimensional framework structure.
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f2: Crystal structure of Na2Fe2(SO4)3.(a) The structure of Na2Fe2(SO4)3 projected along the c axis; and (b) local environment of two independent Fe sites. Green octahedra, yellow tetrahedra and blue spheres show FeO6, SO4 and Na, respectively. Fe ions occupy two kinds of crystallographic sites that have distinctive octahedral geometries. Each FeO6 octahedra share an edge with the crystallographically equivalent octahedra and form Fe2O10 dimers. The SO42− anions interconnect these dimers so as to build up a three-dimensional framework structure.

Mentions: The refined crystal structure of Na2Fe2(SO4)3 is shown in Fig. 2a. To the best of our knowledge, the composition and crystal structure of Na2Fe2(SO4)3 are completely new and have never been reported in the literature. Deviating sharply from most of the AxM2(XO4)3-type compounds adopting the NASICON-related structures, Na2Fe2(SO4)3 does not contain the lantern units [M2(XO4)3], forming a unique structure with alluaudite-type framework. It would be convenient to denote AA′BM2(XO4)3 as general alluaudite-type compounds, where A=partially occupied Na(2), A′=partially occupied Na(3), B=Na(1), M=Fe2+ and X=S in the present case. To the best of our knowledge, this is the first sulphate compound with alluaudite-type framework. The Fe ions occupy octahedral sites that share edges with a crystallographically equivalent octahedron, forming Fe2O10 dimer units. These Fe ions were assigned to two distinct crystallographic sites, Fe(1) and Fe(2) (Fig. 2b). Even though the local structures of Fe(1) and Fe(2) are similar to each other, they are crystallographically distinct as revealed by two doublets in the Mössbauer spectrum (Fig. 1, inset). These isolated edge-sharing Fe2O10 dimers are in turn bridged together by SO4 units strictly by corner-sharing mode, hence forming a three-dimensional framework with large tunnels along c axis. The constituent Na occupies three distinct crystallographic sites; one fully occupied and two partially occupied. This new structure type should open up an entirely new Na2−xM2(SO4)3 (M=Mg, Ti, Mn, Co, Ni, V and VO) family of compounds as potential cathodes/anodes/solid electrolytes for further material exploration. Although NaMnFe2(PO4)3 compounds with alluaudite-type AA′BM2(XO4)3 framework of A, A′=partially occupied Na, B=Mn2+ and Fe2+, M=Mn3+ and Fe3+ and X=P was previously synthesized17, it showed weak electrochemical reactivity. Great advantage to use (SO4)2− instead of (PO4)3− is to stabilize the nearly Na–Fe equi-amount Na2Fe2(SO4)3 compound including only Fe2+ with partially occupied Na+ sites suitable for fast Na+ diffusion upon electrode reaction.


A 3.8-V earth-abundant sodium battery electrode.

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

Crystal structure of Na2Fe2(SO4)3.(a) The structure of Na2Fe2(SO4)3 projected along the c axis; and (b) local environment of two independent Fe sites. Green octahedra, yellow tetrahedra and blue spheres show FeO6, SO4 and Na, respectively. Fe ions occupy two kinds of crystallographic sites that have distinctive octahedral geometries. Each FeO6 octahedra share an edge with the crystallographically equivalent octahedra and form Fe2O10 dimers. The SO42− anions interconnect these dimers so as to build up a three-dimensional framework structure.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Crystal structure of Na2Fe2(SO4)3.(a) The structure of Na2Fe2(SO4)3 projected along the c axis; and (b) local environment of two independent Fe sites. Green octahedra, yellow tetrahedra and blue spheres show FeO6, SO4 and Na, respectively. Fe ions occupy two kinds of crystallographic sites that have distinctive octahedral geometries. Each FeO6 octahedra share an edge with the crystallographically equivalent octahedra and form Fe2O10 dimers. The SO42− anions interconnect these dimers so as to build up a three-dimensional framework structure.
Mentions: The refined crystal structure of Na2Fe2(SO4)3 is shown in Fig. 2a. To the best of our knowledge, the composition and crystal structure of Na2Fe2(SO4)3 are completely new and have never been reported in the literature. Deviating sharply from most of the AxM2(XO4)3-type compounds adopting the NASICON-related structures, Na2Fe2(SO4)3 does not contain the lantern units [M2(XO4)3], forming a unique structure with alluaudite-type framework. It would be convenient to denote AA′BM2(XO4)3 as general alluaudite-type compounds, where A=partially occupied Na(2), A′=partially occupied Na(3), B=Na(1), M=Fe2+ and X=S in the present case. To the best of our knowledge, this is the first sulphate compound with alluaudite-type framework. The Fe ions occupy octahedral sites that share edges with a crystallographically equivalent octahedron, forming Fe2O10 dimer units. These Fe ions were assigned to two distinct crystallographic sites, Fe(1) and Fe(2) (Fig. 2b). Even though the local structures of Fe(1) and Fe(2) are similar to each other, they are crystallographically distinct as revealed by two doublets in the Mössbauer spectrum (Fig. 1, inset). These isolated edge-sharing Fe2O10 dimers are in turn bridged together by SO4 units strictly by corner-sharing mode, hence forming a three-dimensional framework with large tunnels along c axis. The constituent Na occupies three distinct crystallographic sites; one fully occupied and two partially occupied. This new structure type should open up an entirely new Na2−xM2(SO4)3 (M=Mg, Ti, Mn, Co, Ni, V and VO) family of compounds as potential cathodes/anodes/solid electrolytes for further material exploration. Although NaMnFe2(PO4)3 compounds with alluaudite-type AA′BM2(XO4)3 framework of A, A′=partially occupied Na, B=Mn2+ and Fe2+, M=Mn3+ and Fe3+ and X=P was previously synthesized17, it showed weak electrochemical reactivity. Great advantage to use (SO4)2− instead of (PO4)3− is to stabilize the nearly Na–Fe equi-amount Na2Fe2(SO4)3 compound including only Fe2+ with partially occupied Na+ sites suitable for fast Na+ diffusion upon electrode reaction.

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