Evidence for lithium superoxide-like species in the discharge product of a Li-O-2 battery

Title
Evidence for lithium superoxide-like species in the discharge product of a Li-O-2 battery
Author
선양국
Keywords
AIR BATTERIES; ELECTRODES; STABILITY; DESIGN; OXIDES; CELLS
Issue Date
2013-03
Publisher
Royal SOC Chemistry
Citation
Physical Chemistry Chemical Physics,2013, 15(11), P.3764-3771
Abstract
We report on the use of a petroleum coke-based activated carbon (AC) with very high surface area for a Li-O-2 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.
URI
http://pubs.rsc.org/en/Content/ArticleLanding/2013/CP/c3cp00069a#!divAbstracthttp://hdl.handle.net/20.500.11754/55100
ISSN
1463-9076
DOI
10.1039/c3cp00069a
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > ENERGY ENGINEERING(에너지공학과) > Articles
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