Journalartikel

Jahr der Veröffentlichung: 2014

Seiten: 1461-1471

Zeitschrift: Journal of Physical Chemistry C

Bandnummer: 118

Heftnummer: 3

ISSN: 1932-7447

eISSN: 1932-7455

DOI Link: https://doi.org/10.1021/jp4099478

Verlag: American Chemical Society

Abstract: 
Electrochemical reactions in metal-oxygen batteries come along with the consumption or release of gaseous oxygen. We present a novel methodology for investigating electrode reactions and transport phenomena in metal-oxygen batteries by measuring the pressure dynamics in an enclosed gas reservoir above the oxygen electrode. The methodology is exemplified by a room-temperature sodium-oxygen battery forming sodium superoxide (NaO2) in an electrolyte of diethylene glycol dimethyl ether (diglyme) and sodium trifluoromethanesulfonate (NaOSO2CF3, NaOTf). The experiments are supported by microkinetic simulations with a one-dimensional multiphysics continuum model. During galvanostatic cycling over 30 cycles, a constant oxygen consumption/release rate is observed upon discharge/charge. The number of transferred electrons per oxygen molecule is calculated to 1.01 +/- 0.02 and 1.03 +/- 0.02 for discharge and charge, respectively, confirming the nature of the oxygen reaction product as superoxide O-2(-). The same ratio is observed in cyclic voltammetry experiments with low scan rate (<1 mV/s). However, at higher scan rates, the ratio increases as a result of oxygen transport limitations in the electrolyte. We introduce electrochemical pressure impedance spectroscopy (EPIS) for simultaneously analyzing current, voltage, and pressure of electrochemical cells. Pressure recording significantly increases the sensitivity of impedance toward oxygen transport properties of the porous electrode systems. In addition, we report experimental data on the diffusion coefficient and solubility of oxygen in electrolyte solutions as important parameters for the microkinetic models.

Harvard-Zitierstil: Hartmann, P., Grübl, D., Sommer, H., Janek, J., Bessler, W. and Adelhelm, P. (2014) Pressure Dynamics in Metal-Oxygen (Metal-Air) Batteries: A Case Study on Sodium Superoxide Cells, Journal of Physical Chemistry C, 118(3), pp. 1461-1471. https://doi.org/10.1021/jp4099478

APA-Zitierstil: Hartmann, P., Grübl, D., Sommer, H., Janek, J., Bessler, W., & Adelhelm, P. (2014). Pressure Dynamics in Metal-Oxygen (Metal-Air) Batteries: A Case Study on Sodium Superoxide Cells. Journal of Physical Chemistry C. 118(3), 1461-1471. https://doi.org/10.1021/jp4099478