A highly concentrated ether electrolyte for efficient Na-ion half cells

Research output: Contribution to conferencePoster

Abstract

Na-ion batteries are amongst the most appealing alternatives to Li-ion batteries due to a similar intercalation chemistry and lower cost. Novel Na-ion chemistries are often assessed in half cells that contain Na-metal counter and reference electrodes (Figure 1). These electrodes are highly reactive and require a passivation layer to work, which is formed from electrolyte decomposition products. Recently, however, the passivation layer of standard carbonate electrolytes on sodium metal was found to be rather instable, raising questions about the reliability of both Na-ion half cells and other low voltage anodes. [1]

This work presents a dimethoxyethane (DME) / sodium bis(fluorosulfonyl)imide (NaFSI) (2/1 (n/n)) electrolyte that forms a stable and resilient passivation layer on sodium metal, as indicated by highly reversible sodium plating/stripping. Further investigation of the passivation layers by post-mortem FTIR and 1H-NMR analysis reveals that conventional organic carbonate based electrolytes decompose to organic salts such as sodium ethyl dicarbonate. In contrast, the DME/NaFSI electrolyte forms ethereal and alkoxide species as well as inorganic salts derived from the FSI anion. These compounds ensure sodium metal passivation and thereby enable more reliable and efficient testing in Na-ion half cells.
Original languageEnglish
Publication statusPublished - 27 Sep 2016
Event2nd Graz Battery Days - Graz, Austria
Duration: 27 Sep 201628 Sep 2016

Conference

Conference2nd Graz Battery Days
CountryAustria
CityGraz
Period27/09/1628/09/16

Fields of Expertise

  • Advanced Materials Science

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)

Projects

Cite this

Schafzahl, L., Wilkening, M., & Freunberger, S. (2016). A highly concentrated ether electrolyte for efficient Na-ion half cells. Poster session presented at 2nd Graz Battery Days, Graz, Austria.