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Title: Electrochemical Oxidation of Lithium Carbonate Generates Singlet Oxygen

Solid alkali metal carbonates are universal passivation layer components of intercalation battery materials and common side products in metal-O 2 batteries, and are believed to form and decompose reversibly in metal-O 2/CO 2 cells. In these cathodes, Li 2CO 3 decomposes to CO 2 when exposed to potentials above 3.8 V vs. Li/Li +. However, O 2 evolution, as would be expected according to the decomposition reaction 2 Li 2CO 3 → 4 Li ++4 e +2 CO 2+O 2, is not detected. O atoms are thus unaccounted for, which was previously ascribed to unidentified parasitic reactions. Here, we show that highly reactive singlet oxygen ( 1O 2) forms upon oxidizing Li 2CO 3 in an aprotic electrolyte and therefore does not evolve as O 2. These results have substantial implications for the long-term cyclability of batteries: they underpin the importance of avoiding 1O 2 in metal-O 2 batteries, question the possibility of a reversible metal-O 2/CO 2 battery based on a carbonate discharge product, and help explain the interfacial reactivity of transition-metal cathodes with residual Li 2CO 3.
Authors:
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [2] ; ORCiD logo [1]
  1. Graz Univ. of Technology, Graz (Austria)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Published Article
Journal Name:
Angewandte Chemie (International Edition)
Additional Journal Information:
Journal Name: Angewandte Chemie (International Edition); Journal Volume: 57; Journal Issue: 19; Related Information: © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.; Journal ID: ISSN 1433-7851
Publisher:
Wiley
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; electrochemistry; lithium batteries; lithium carbonate; reaction mechanisms; singlet oxygen
OSTI Identifier:
1433266
Alternate Identifier(s):
OSTI ID: 1433267; OSTI ID: 1460317

Mahne, Nika, Renfrew, Sara E., McCloskey, Bryan D., and Freunberger, Stefan A.. Electrochemical Oxidation of Lithium Carbonate Generates Singlet Oxygen. United States: N. p., Web. doi:10.1002/anie.201802277.
Mahne, Nika, Renfrew, Sara E., McCloskey, Bryan D., & Freunberger, Stefan A.. Electrochemical Oxidation of Lithium Carbonate Generates Singlet Oxygen. United States. doi:10.1002/anie.201802277.
Mahne, Nika, Renfrew, Sara E., McCloskey, Bryan D., and Freunberger, Stefan A.. 2018. "Electrochemical Oxidation of Lithium Carbonate Generates Singlet Oxygen". United States. doi:10.1002/anie.201802277.
@article{osti_1433266,
title = {Electrochemical Oxidation of Lithium Carbonate Generates Singlet Oxygen},
author = {Mahne, Nika and Renfrew, Sara E. and McCloskey, Bryan D. and Freunberger, Stefan A.},
abstractNote = {Solid alkali metal carbonates are universal passivation layer components of intercalation battery materials and common side products in metal-O2 batteries, and are believed to form and decompose reversibly in metal-O2/CO2 cells. In these cathodes, Li2CO3 decomposes to CO2 when exposed to potentials above 3.8 V vs. Li/Li+. However, O2 evolution, as would be expected according to the decomposition reaction 2 Li2CO3 → 4 Li++4 e–+2 CO2+O2, is not detected. O atoms are thus unaccounted for, which was previously ascribed to unidentified parasitic reactions. Here, we show that highly reactive singlet oxygen (1O2) forms upon oxidizing Li2CO3 in an aprotic electrolyte and therefore does not evolve as O2. These results have substantial implications for the long-term cyclability of batteries: they underpin the importance of avoiding 1O2 in metal-O2 batteries, question the possibility of a reversible metal-O2/CO2 battery based on a carbonate discharge product, and help explain the interfacial reactivity of transition-metal cathodes with residual Li2CO3.},
doi = {10.1002/anie.201802277},
journal = {Angewandte Chemie (International Edition)},
number = 19,
volume = 57,
place = {United States},
year = {2018},
month = {3}
}