Issue 11, 2013

Evidence for lithium superoxide-like species in the discharge product of a Li–O2 battery

Abstract

We report on the use of a petroleum coke-based activated carbon (AC) with very high surface area for a Li–O2 battery cathode without the use of any additional metal catalysts. Electrochemical measurement in a tetra(ethylene) glycol dimethyl ether–lithium triflate (TEGDME–LiCF3SO3) electrolyte results in two voltage plateaus during charging at 3.2–3.5 and 4.2–4.3 V versus Li+/Li. Herein we present evidence from Raman and magnetic measurements that the lower plateau corresponds to a form of lithium peroxide with superoxide-like properties characterized by a low temperature magnetic phase transition and a high O–O stretching frequency (1125 cm−1). The magnetic phase transition and the high O–O stretching frequency disappear when charged to above 3.7 V. Theoretical calculations indicate that a surface superoxide structure on lithium peroxide clusters and some lithium peroxide surfaces have an unpaired electron and a high O–O stretching frequency that help explain the observations. These results provide evidence that the form of the lithium peroxide discharge product is important to obtaining a low charge overpotential, and thus improving the round-trip efficiency between discharge and charge.

Graphical abstract: Evidence for lithium superoxide-like species in the discharge product of a Li–O2 battery

Supplementary files

Article information

Article type
Paper
Submitted
08 Jan 2013
Accepted
10 Jan 2013
First published
17 Jan 2013

Phys. Chem. Chem. Phys., 2013,15, 3764-3771

Evidence for lithium superoxide-like species in the discharge product of a Li–O2 battery

J. Yang, D. Zhai, H. Wang, K. C. Lau, J. A. Schlueter, P. Du, D. J. Myers, Y. Sun, L. A. Curtiss and K. Amine, Phys. Chem. Chem. Phys., 2013, 15, 3764 DOI: 10.1039/C3CP00069A

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