Solvothermal synthesis of Sn3N4 as a high capacity sodium-ion anode: theoretical and experimental study of its storage mechanism
Solvothermal synthesis of Sn3N4 as a high capacity sodium-ion anode: theoretical and experimental study of its storage mechanism
A new simple and scalable method to synthesise spinel-structured Sn3N4 has been developed using SnCl4 and LiNH2 precursors under solvothermal conditions. Nanocrystalline Sn3N4 with a crystallite size < 10 nm was produced and tested as anode material in sodium half cells, demonstrating a very high reversible (de-sodiation) capacity of ∼850 mA h g-1 measured over 50 cycles, the highest reported reversible capacity for a sodium anode apart from sodium itself. Ex situ X-ray absorption spectroscopy and X-ray diffraction show that the electrochemical reactions are reversible and that Sn3N4 is recovered upon re-oxidation. X-ray diffraction shows that the peaks associated with Sn3N4 reflections become narrower during discharge (reduction), evidencing that the smaller Sn3N4 particles are primarily involved in the electrochemical reactions, and broadening of the peaks is reversibly recovered upon oxidation. The analysis of the near edge X-ray absorption data (XANES) shows that the Sn oxidation state decreases during reduction and nearly recovers the initial value during oxidation. DFT calculations suggest that the insertion of Na into the Sn3N4 surface followed by substitution of tetrahedral Sn by Na is energetically favourable, and evidence of the removal of tetrahedral Sn from the spinel Sn3N4 structure is obtained from the analysis of the extended X-ray absorption fine-structure (EXAFS) measurements of reduced electrodes, which also show the recovery of the pristine structure at the end of oxidation. DFT also shows that Sn substitution by Na is only favourable at the Sn3N4 surface (not for bulk Sn3N4), in agreement with the electrochemical characterisation that shows that controlling the nanoparticle size is crucial to achieve full utilisation of Sn3N4 (and thus high capacity).
16437-16450
Fitch, Samuel
6e21c66c-99c4-4b1b-b8ff-043a0cc2e884
Cibin, Giannantonio
e2cdeddc-2f78-416e-9507-3894ad3768c9
Hepplestone, Steven
0d20a092-2ab8-489f-a5f5-4849145532dc
Garcia-Araez, Nuria
9358a0f9-309c-495e-b6bf-da985ad81c37
Hector, Andrew L.
f19a8f31-b37f-4474-b32a-b7cf05b9f0e5
28 August 2020
Fitch, Samuel
6e21c66c-99c4-4b1b-b8ff-043a0cc2e884
Cibin, Giannantonio
e2cdeddc-2f78-416e-9507-3894ad3768c9
Hepplestone, Steven
0d20a092-2ab8-489f-a5f5-4849145532dc
Garcia-Araez, Nuria
9358a0f9-309c-495e-b6bf-da985ad81c37
Hector, Andrew L.
f19a8f31-b37f-4474-b32a-b7cf05b9f0e5
Fitch, Samuel, Cibin, Giannantonio, Hepplestone, Steven, Garcia-Araez, Nuria and Hector, Andrew L.
(2020)
Solvothermal synthesis of Sn3N4 as a high capacity sodium-ion anode: theoretical and experimental study of its storage mechanism.
Journal of Materials Chemistry A, 8 (32), .
(doi:10.1039/D0TA04034G).
Abstract
A new simple and scalable method to synthesise spinel-structured Sn3N4 has been developed using SnCl4 and LiNH2 precursors under solvothermal conditions. Nanocrystalline Sn3N4 with a crystallite size < 10 nm was produced and tested as anode material in sodium half cells, demonstrating a very high reversible (de-sodiation) capacity of ∼850 mA h g-1 measured over 50 cycles, the highest reported reversible capacity for a sodium anode apart from sodium itself. Ex situ X-ray absorption spectroscopy and X-ray diffraction show that the electrochemical reactions are reversible and that Sn3N4 is recovered upon re-oxidation. X-ray diffraction shows that the peaks associated with Sn3N4 reflections become narrower during discharge (reduction), evidencing that the smaller Sn3N4 particles are primarily involved in the electrochemical reactions, and broadening of the peaks is reversibly recovered upon oxidation. The analysis of the near edge X-ray absorption data (XANES) shows that the Sn oxidation state decreases during reduction and nearly recovers the initial value during oxidation. DFT calculations suggest that the insertion of Na into the Sn3N4 surface followed by substitution of tetrahedral Sn by Na is energetically favourable, and evidence of the removal of tetrahedral Sn from the spinel Sn3N4 structure is obtained from the analysis of the extended X-ray absorption fine-structure (EXAFS) measurements of reduced electrodes, which also show the recovery of the pristine structure at the end of oxidation. DFT also shows that Sn substitution by Na is only favourable at the Sn3N4 surface (not for bulk Sn3N4), in agreement with the electrochemical characterisation that shows that controlling the nanoparticle size is crucial to achieve full utilisation of Sn3N4 (and thus high capacity).
Text
d0ta04034g
- Version of Record
Text
Sn3N4 manuscript revised
Restricted to Repository staff only
Request a copy
More information
Accepted/In Press date: 19 July 2020
Published date: 28 August 2020
Additional Information:
Funding Information:
The authors thank EPSRC for funding an early career fellowship to NGA (EP/N024303/1) and the Smartlab diffractometer (EP/ K00509X/1 and EP/K009877/1). Thanks also to Diamond for beam time at B18 under the Energy Materials block allocation grant administered by Prof. Alan Chadwick (SP14239), and to Prof. Andrea Russell for access to the Raman spectrometer. We acknowledge the use of the EPSRC-funded National Chemical Database service hosted by the Royal Society of Chemistry.
Publisher Copyright:
© The Royal Society of Chemistry.
Identifiers
Local EPrints ID: 442783
URI: http://eprints.soton.ac.uk/id/eprint/442783
ISSN: 2050-7488
PURE UUID: 707a25d2-f5da-4648-ab7b-1c713282f266
Catalogue record
Date deposited: 27 Jul 2020 16:30
Last modified: 17 Mar 2024 03:54
Export record
Altmetrics
Contributors
Author:
Samuel Fitch
Author:
Giannantonio Cibin
Author:
Steven Hepplestone
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics