Why charging Li-air batteries with current low-voltage mediators is slow and singlet oxygen does not explain degradation

被引：56

作者：

Ahn, Sunyhik ^{[1
]}

Zor, Ceren ^{[1
]}

Yang, Sixie ^{[1
]}

Lagnoni, Marco ^{[2
]}

Dewar, Daniel ^{[1
]}

Nimmo, Tammy ^{[1
]}

Chau, Chloe ^{[1
]}

Jenkins, Max ^{[1
]}

Kibler, Alexander J. ^{[3
]}

Pateman, Alexander ^{[1
]}

Rees, Gregory J. ^{[1
]}

Gao, Xiangwen ^{[1
]}

Adamson, Paul ^{[1
]}

Grobert, Nicole ^{[1
]}

Bertei, Antonio ^{[2
]}

Johnson, Lee R. ^{[3
]}

Bruce, Peter G. ^{[1
,4
]}

机构：

[1] Univ Oxford, Dept Mat, Oxford, England

[2] Univ Pisa, Dept Civil & Ind Engn, Pisa, Italy

[3] Univ Nottingham, Sch Chem, Nottingham Appl Mat & Interfaces Grp, Nottingham, England

[4] Univ Oxford, Dept Chem, Oxford, England

来源：

NATURE CHEMISTRY | 2023年 / 15卷 / 07期

基金：

英国工程与自然科学研究理事会;

关键词：

SCANNING ELECTROCHEMICAL MICROSCOPY; ELECTRON-TRANSFER; LI-O-2; BATTERIES; ANALYTICAL APPROXIMATION; REDOX MEDIATOR; FREE-ENERGY; LITHIUM; OXIDATION; DISCHARGE; RATES;

D O I：

10.1038/s41557-023-01203-3

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

Although Li-air rechargeable batteries offer higher energy densities than lithium-ion batteries, the insulating Li2O2 formed during discharge hinders rapid, efficient re-charging. Redox mediators are used to facilitate Li2O2 oxidation; however, fast kinetics at a low charging voltage are necessary for practical applications and are yet to be achieved. We investigate the mechanism of Li2O2 oxidation by redox mediators. The rate-limiting step is the outer-sphere one-electron oxidation of Li2O2 to LiO2, which follows Marcus theory. The second step is dominated by LiO2 disproportionation, forming mostly triplet-state O-2. The yield of singlet-state O-2 depends on the redox potential of the mediator in a way that does not correlate with electrolyte degradation, in contrast to earlier views. Our mechanistic understanding explains why current low-voltage mediators (<+3.3 V) fail to deliver high rates (the maximum rate is at +3.74 V) and suggests important mediator design strategies to deliver sufficiently high rates for fast charging at potentials closer to the thermodynamic potential of Li2O2 oxidation (+2.96 V).

引用

页码：1022 / +

页数：12

共 70 条

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