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The effect of water on quinone redox mediators in nonaqueous Li-O2 batteries

The effect of water on quinone redox mediators in nonaqueous Li-O2 batteries
The effect of water on quinone redox mediators in nonaqueous Li-O2 batteries
The parasitic reactions associated with reduced oxygen species and the difficulty in achieving the high theoretical capacity have been major issues plaguing development of practical nonaqueous Li-O2 batteries. We hereby address the above issues by exploring the synergistic effect of 2,5-di-tert-butyl-1,4-benzoquinone and H2O on the oxygen chemistry in a nonaqueous Li-O2 battery. Water stabilizes the quinone monoanion and dianion, shifting the reduction potentials of the quinone and monoanion to more positive values (vs Li/Li+). When water and the quinone are used together in a (largely) nonaqueous Li-O2 battery, the cell discharge operates via a two-electron oxygen reduction reaction to form Li2O2, with the battery discharge voltage, rate, and capacity all being considerably increased and fewer side reactions being detected. Li2O2 crystals can grow up to 30 μm, more than an order of magnitude larger than cases with the quinone alone or without any additives, suggesting that water is essential to promoting a solution dominated process with the quinone on discharging. The catalytic reduction of O2 by the quinone monoanion is predominantly responsible for the attractive features mentioned above. Water stabilizes the quinone monoanion via hydrogen-bond formation and by coordination of the Li+ ions, and it also helps increase the solvation, concentration, lifetime, and diffusion length of reduced oxygen species that dictate the discharge voltage, rate, and capacity of the battery. When a redox mediator is also used to aid the charging process, a high-power, high energy density, rechargeable Li-O2 battery is obtained.
0002-7863
1428-1437
Liu, Tao
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Frith, James T
349b19de-36a7-4136-9f2d-af8160311d38
Kim, Gunwoo
cf5f9ada-ef75-4b69-97ad-510d6cdfb425
Kerber, Racehl N.
13c82510-15d5-43ea-9ce0-a7c050e1080f
Dubouis, Nicolas
b2f5fca7-ff91-432e-921b-5a87655d656a
Shao, Yuanlong
53089689-b3a3-4597-934e-fafed0d9120c
Liu, Zigeng
5407a2de-133e-4bfb-acfa-249ab105a9d9
Magusin, Pieter C. M. M.
89f6ffb0-006a-4ef5-a6b7-7c990ea92f01
Casford, Michael T. L.
5315ef15-3867-45fa-ac0a-3199baf7581e
Garcia-Araez, Nuria
9358a0f9-309c-495e-b6bf-da985ad81c37
Grey, Clare P.
36cd015b-a910-4b25-869b-fabc62e50602
Liu, Tao
01fc84ea-a1b9-4207-a11b-dc9b6fe27824
Frith, James T
349b19de-36a7-4136-9f2d-af8160311d38
Kim, Gunwoo
cf5f9ada-ef75-4b69-97ad-510d6cdfb425
Kerber, Racehl N.
13c82510-15d5-43ea-9ce0-a7c050e1080f
Dubouis, Nicolas
b2f5fca7-ff91-432e-921b-5a87655d656a
Shao, Yuanlong
53089689-b3a3-4597-934e-fafed0d9120c
Liu, Zigeng
5407a2de-133e-4bfb-acfa-249ab105a9d9
Magusin, Pieter C. M. M.
89f6ffb0-006a-4ef5-a6b7-7c990ea92f01
Casford, Michael T. L.
5315ef15-3867-45fa-ac0a-3199baf7581e
Garcia-Araez, Nuria
9358a0f9-309c-495e-b6bf-da985ad81c37
Grey, Clare P.
36cd015b-a910-4b25-869b-fabc62e50602

Liu, Tao, Frith, James T, Kim, Gunwoo, Kerber, Racehl N., Dubouis, Nicolas, Shao, Yuanlong, Liu, Zigeng, Magusin, Pieter C. M. M., Casford, Michael T. L., Garcia-Araez, Nuria and Grey, Clare P. (2018) The effect of water on quinone redox mediators in nonaqueous Li-O2 batteries. Journal of the American Chemical Society, 140 (4), 1428-1437. (doi:10.1021/jacs.7b11007).

Record type: Article

Abstract

The parasitic reactions associated with reduced oxygen species and the difficulty in achieving the high theoretical capacity have been major issues plaguing development of practical nonaqueous Li-O2 batteries. We hereby address the above issues by exploring the synergistic effect of 2,5-di-tert-butyl-1,4-benzoquinone and H2O on the oxygen chemistry in a nonaqueous Li-O2 battery. Water stabilizes the quinone monoanion and dianion, shifting the reduction potentials of the quinone and monoanion to more positive values (vs Li/Li+). When water and the quinone are used together in a (largely) nonaqueous Li-O2 battery, the cell discharge operates via a two-electron oxygen reduction reaction to form Li2O2, with the battery discharge voltage, rate, and capacity all being considerably increased and fewer side reactions being detected. Li2O2 crystals can grow up to 30 μm, more than an order of magnitude larger than cases with the quinone alone or without any additives, suggesting that water is essential to promoting a solution dominated process with the quinone on discharging. The catalytic reduction of O2 by the quinone monoanion is predominantly responsible for the attractive features mentioned above. Water stabilizes the quinone monoanion via hydrogen-bond formation and by coordination of the Li+ ions, and it also helps increase the solvation, concentration, lifetime, and diffusion length of reduced oxygen species that dictate the discharge voltage, rate, and capacity of the battery. When a redox mediator is also used to aid the charging process, a high-power, high energy density, rechargeable Li-O2 battery is obtained.

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Accepted/In Press date: 18 January 2018
e-pub ahead of print date: 18 January 2018
Published date: 31 January 2018

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Local EPrints ID: 417697
URI: http://eprints.soton.ac.uk/id/eprint/417697
ISSN: 0002-7863
PURE UUID: d3998f97-f590-421c-ac66-de6f570d6e5f
ORCID for Nuria Garcia-Araez: ORCID iD orcid.org/0000-0001-9095-2379

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Date deposited: 12 Feb 2018 17:30
Last modified: 15 Sep 2021 05:19

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Contributors

Author: Tao Liu
Author: James T Frith
Author: Gunwoo Kim
Author: Racehl N. Kerber
Author: Nicolas Dubouis
Author: Yuanlong Shao
Author: Zigeng Liu
Author: Pieter C. M. M. Magusin
Author: Michael T. L. Casford
Author: Clare P. Grey

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