Towards standard electrolytes for sodium-ion batteries: physical properties, ion solvation and ion-pairing in alkyl carbonate solvents
Artikel i vetenskaplig tidskrift, 2020

The currently emerging sodium-ion battery technology is in need of an optimized standard organic solvent electrolyte based on solid and directly comparable data. With this aim we have made a systematic study of "simple"electrolyte systems consisting of two sodium salts (NaTFSI and NaPF6) dissolved in three different alkyl carbonate solvents (EC, PC, DMC) within a wide range of salt concentrations and investigated: (i) their more macroscopic physico-chemical properties such as ionic conductivity, viscosity, thermal stability, and (ii) the molecular level properties such as ion-pairing and solvation. From this all electrolytes were found to have useful thermal operational windows and electrochemical stability windows, allowing for large scale energy storage technologies focused on load levelling or (to a less extent) electric vehicles, and ionic conductivities on par with analogous lithium-ion battery electrolytes, giving promise to also be power performant. Furthermore, at the molecular level the NaPF6-based electrolytes are more dissociated than the NaTFSI-based ones because of the higher ionic association strength of TFSI compared to PF6- while two different conformers of DMC participate in the Na+ first solvation shells-a Na+ affected conformational equilibrium and induced polarity of DMC. The non-negligible presence of DMC in the Na+ first solvation shells increases as a function of salt concentration. Overall, these results should both have a general impact on the design of more performant Na-conducting electrolytes and provide useful insight on the very details of the importance of DMC conformers in any cation solvation studies.

Författare

Damien Monti

Centre national de la recherche scientifique (CNRS)

Chalmers, Fysik, Materialfysik

Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)

Erlendur Jonsson

Chalmers, Fysik, Materialfysik

University of Cambridge

Andrea Boschin

Chalmers, Fysik, Materialfysik

M. R. Palacin

Centre national de la recherche scientifique (CNRS)

Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)

A. Ponrouch

Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)

Centre national de la recherche scientifique (CNRS)

Patrik Johansson

Centre national de la recherche scientifique (CNRS)

Chalmers, Fysik, Materialfysik

Physical Chemistry Chemical Physics

1463-9076 (ISSN) 1463-9084 (eISSN)

Vol. 22 39 22768-22777

Ämneskategorier

Oorganisk kemi

Materialkemi

Annan kemiteknik

DOI

10.1039/d0cp03639k

PubMed

33021285

Mer information

Senast uppdaterat

2021-01-21