Journal article

Publication year: 2015

Pages: 11-21

Journal: ECS Transactions

Volume number: 69

Issue number: 19

ISSN: 1938-5862

eISSN: 1938-6737

DOI Link: https://doi.org/10.1149/06919.0011ecst

Publisher: The Electrochemical Society

Abstract: 

Lithium-oxygen cells with organic electrolyte suffer high overpotentials during charge, indicating asymmetric charge/discharge reaction mechanisms. We present a multi-physics dynamic modeling and simulation study of the Li/O₂ cell cycling behavior. We present three different multi-step mechanisms of the 2 Li + O₂ Li₂O₂ cell reaction, (A) a reversible 5-step mechanism, (B) a partially irreversible 6-step mechanism, and (C) a partially irreversible 8-step mechanism that includes reactions of a redox mediator. Model predictions are compared to experimental galvanostatic cycling data of Swagelok cells without and with 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) as redox mediator. All mechanisms are able to predict the discharge behavior in good agreement to the experimental results. The experimentally observed high charge overpotentials as well as their reduction by using a redox mediator can be qualitatively reproduced with the irreversible reaction mechanisms. However, the particular shape of the experimental charge curve with continuously increasing charge overpotential cannot be reproduced with the present mechanisms.

Harvard Citation style: Grübl, D., Bergner, B., Janek, J. and Bessler, W. (2015) Dynamic Modeling of the Reaction Mechanism in a Li/O2 Cell: Influence of a Redox Mediator, ECS Transactions, 69(19), pp. 11-21. https://doi.org/10.1149/06919.0011ecst

APA Citation style: Grübl, D., Bergner, B., Janek, J., & Bessler, W. (2015). Dynamic Modeling of the Reaction Mechanism in a Li/O2 Cell: Influence of a Redox Mediator. ECS Transactions. 69(19), 11-21. https://doi.org/10.1149/06919.0011ecst