Journalartikel

Jahr der Veröffentlichung: 2015

Seiten: 22778-22786

Zeitschrift: Journal of Physical Chemistry C

Bandnummer: 119

Heftnummer: 40

ISSN: 1932-7447

eISSN: 1932-7455

DOI Link: https://doi.org/10.1021/acs.jpcc.5b06007

Verlag: American Chemical Society

Abstract: 
Sodium-oxygen cells with sodium superoxide (NaO2) as discharge product show charge and discharge characteristics with very low overvoltage, different from lithium/oxygen cells. Here, it is shown that the discharge of a nonaqueous sodium/oxygen cell proceeds via the electrochemical formation of superoxide (O-2(-)), its dissolution in the liquid electrolyte, and subsequent precipitation together with sodium ions as solid sodium superoxide. Charge proceeds in the counter-direction by consumption of dissolved superoxide anions and dissolution of NaO2. Indirect evidence for the solution-precipitation route is provided by theoretical results on the electronic structure of NaO2 and the conclusion that the electronic conductivity of NaO2 is too low to allow,direct electrochemical growth and dissolution. Direct evidence for the solution-precipitation route is provided by results from charge/discharge studies of a three-electrode cell in which preformed NaO2 is being decomposed without direct electronic contact to the charging circuit. An analytical model for the overvoltage as a function of electrode coverage with electrically insulating discharge product complements the theoretical and experimental results and supports the mechanistic findings.

Harvard-Zitierstil: Hartmann, P., Heinemann, M., Bender, C., Graf, K., Baumann, R., Adelhelm, P., et al. (2015) Discharge and Charge Reaction Paths in Sodium-Oxygen Batteries: Does NaO2 Form by Direct Electrochemical Growth or by Precipitation from Solution?, Journal of Physical Chemistry C, 119(40), pp. 22778-22786. https://doi.org/10.1021/acs.jpcc.5b06007

APA-Zitierstil: Hartmann, P., Heinemann, M., Bender, C., Graf, K., Baumann, R., Adelhelm, P., Heiliger, C., & Janek, J. (2015). Discharge and Charge Reaction Paths in Sodium-Oxygen Batteries: Does NaO2 Form by Direct Electrochemical Growth or by Precipitation from Solution?. Journal of Physical Chemistry C. 119(40), 22778-22786. https://doi.org/10.1021/acs.jpcc.5b06007