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Title: Investigating Sodium Storage Mechanisms in Tin Anodes: A Combined Pair Distribution Function Analysis, Density Functional Theory, and Solid-State NMR Approach

Here, the alloying mechanism of high-capacity tin anodes for sodium-ion batteries is investigated using a combined theoretical and experimental approach. Ab initio random structure searching (AIRSS) and high-throughput screening using a species-swap method provide insights into a range of possible sodium–tin structures. These structures are linked to experiments using both average and local structure probes in the form of operando pair distribution function analysis, X-ray diffraction, and 23Na solid-state nuclear magnetic resonance (ssNMR), along with ex situ 119Sn ssNMR. Through this approach, we propose structures for the previously unidentified crystalline and amorphous intermediates. The first electrochemical process of sodium insertion into tin results in the conversion of crystalline tin into a layered structure consisting of mixed Na/Sn occupancy sites intercalated between planar hexagonal layers of Sn atoms (approximate stoichiometry NaSn 3). Following this, NaSn 2, which is predicted to be thermodynamically stable by AIRSS, forms; this contains hexagonal layers closely related to NaSn 3, but has no tin atoms between the layers. NaSn 2 is broken down into an amorphous phase of approximate composition Na 1.2Sn. Reverse Monte Carlo refinements of an ab initio molecular dynamics model of this phase show that the predominant tin connectivity is chains. Further reactionmore » with sodium results in the formation of structures containing Sn–Sn dumbbells, which interconvert through a solid-solution mechanism. These structures are based upon Na 5–xSn 2, with increasing occupancy of one of its sodium sites commensurate with the amount of sodium added. ssNMR results indicate that the final product, Na 15Sn 4, can store additional sodium atoms as an off-stoichiometry compound (Na 15+xSn 4) in a manner similar to Li 15Si 4.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [3] ;  [4] ;  [1] ; ORCiD logo [1]
  1. Univ. of Cambridge, Cambridge (United Kingdom)
  2. Univ. of Cambridge, Cambridge (United Kingdom); Gonville and Caius College, Cambridge (United Kingdom); Diamond Light Source Ltd., Didcot (United Kingdom)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
  4. Univ. of Cambridge, Cambridge (United Kingdom); Tohoku Univ., Sendai (Japan)
Publication Date:
Grant/Contract Number:
AC02-06CH11357; AC02-05CH11231
Type:
Published Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 139; Journal Issue: 21; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1364066
Alternate Identifier(s):
OSTI ID: 1374423

Stratford, Joshua M., Mayo, Martin, Allan, Phoebe K., Pecher, Oliver, Borkiewicz, Olaf J., Wiaderek, Kamila M., Chapman, Karena W., Pickard, Chris J., Morris, Andrew J., and Grey, Clare P.. Investigating Sodium Storage Mechanisms in Tin Anodes: A Combined Pair Distribution Function Analysis, Density Functional Theory, and Solid-State NMR Approach. United States: N. p., Web. doi:10.1021/jacs.7b01398.
Stratford, Joshua M., Mayo, Martin, Allan, Phoebe K., Pecher, Oliver, Borkiewicz, Olaf J., Wiaderek, Kamila M., Chapman, Karena W., Pickard, Chris J., Morris, Andrew J., & Grey, Clare P.. Investigating Sodium Storage Mechanisms in Tin Anodes: A Combined Pair Distribution Function Analysis, Density Functional Theory, and Solid-State NMR Approach. United States. doi:10.1021/jacs.7b01398.
Stratford, Joshua M., Mayo, Martin, Allan, Phoebe K., Pecher, Oliver, Borkiewicz, Olaf J., Wiaderek, Kamila M., Chapman, Karena W., Pickard, Chris J., Morris, Andrew J., and Grey, Clare P.. 2017. "Investigating Sodium Storage Mechanisms in Tin Anodes: A Combined Pair Distribution Function Analysis, Density Functional Theory, and Solid-State NMR Approach". United States. doi:10.1021/jacs.7b01398.
@article{osti_1364066,
title = {Investigating Sodium Storage Mechanisms in Tin Anodes: A Combined Pair Distribution Function Analysis, Density Functional Theory, and Solid-State NMR Approach},
author = {Stratford, Joshua M. and Mayo, Martin and Allan, Phoebe K. and Pecher, Oliver and Borkiewicz, Olaf J. and Wiaderek, Kamila M. and Chapman, Karena W. and Pickard, Chris J. and Morris, Andrew J. and Grey, Clare P.},
abstractNote = {Here, the alloying mechanism of high-capacity tin anodes for sodium-ion batteries is investigated using a combined theoretical and experimental approach. Ab initio random structure searching (AIRSS) and high-throughput screening using a species-swap method provide insights into a range of possible sodium–tin structures. These structures are linked to experiments using both average and local structure probes in the form of operando pair distribution function analysis, X-ray diffraction, and 23Na solid-state nuclear magnetic resonance (ssNMR), along with ex situ 119Sn ssNMR. Through this approach, we propose structures for the previously unidentified crystalline and amorphous intermediates. The first electrochemical process of sodium insertion into tin results in the conversion of crystalline tin into a layered structure consisting of mixed Na/Sn occupancy sites intercalated between planar hexagonal layers of Sn atoms (approximate stoichiometry NaSn3). Following this, NaSn2, which is predicted to be thermodynamically stable by AIRSS, forms; this contains hexagonal layers closely related to NaSn3, but has no tin atoms between the layers. NaSn2 is broken down into an amorphous phase of approximate composition Na1.2Sn. Reverse Monte Carlo refinements of an ab initio molecular dynamics model of this phase show that the predominant tin connectivity is chains. Further reaction with sodium results in the formation of structures containing Sn–Sn dumbbells, which interconvert through a solid-solution mechanism. These structures are based upon Na5–xSn2, with increasing occupancy of one of its sodium sites commensurate with the amount of sodium added. ssNMR results indicate that the final product, Na15Sn4, can store additional sodium atoms as an off-stoichiometry compound (Na15+xSn4) in a manner similar to Li15Si4.},
doi = {10.1021/jacs.7b01398},
journal = {Journal of the American Chemical Society},
number = 21,
volume = 139,
place = {United States},
year = {2017},
month = {5}
}