Controllable and stable organometallic redox mediators for lithium oxygen batteries

Kwak, Won‐Jin; Mahammed, Atif; Kim, Hun; Nguyen, Trung Thien; Gross, Zeev; Aurbach, Doron; Sun, Yang Kook

doi:10.1039/c9mh01043b

Cited by 18 publications

(18 citation statements)

References 47 publications

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“…Recently, Co, Mn, and Cu complexes of TFPCorrH 3 and T(2,6-F 2 )PCorrH 3 were tested as redox mediators for the OER in Li-O 2 batteries. 65 The role of these species is to be easily oxidized and in this form, they should oxidize the Li 2 O 2 formed as the ORR product in the cell. A drawback that limits the efficiency of these cells is the instability of the redox mediators.…”

Section: Water Oxidationmentioning

confidence: 99%

“…Even free-base corroles have been proposed as electrocatalysts for the HER. It has been reported 65 that the free-base corroles were investigated as electrocatalysts for the HER.…”

Section: Hydrogen Evolution Reaction (Her)mentioning

confidence: 99%

“…42 The proposed catalytic cycle for the HER catalysed by free-base corroles. 65 with the process starting with the formation of the protonated corrole, which can then be reduced, leading to H 2 evolution. First-row transition metal complexes of corrole have been demonstrated to be the most efficient alternatives to Pt catalysts for these important clean energy conversion processes, i.e., the ORR, OER, and HER.…”

Section: Hydrogen Evolution Reaction (Her)mentioning

confidence: 99%

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Corroles at work: a small macrocycle for great applications

2022

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Section: Water Oxidationmentioning

confidence: 99%

“…Even free-base corroles have been proposed as electrocatalysts for the HER. It has been reported 65 that the free-base corroles were investigated as electrocatalysts for the HER.…”

Section: Hydrogen Evolution Reaction (Her)mentioning

confidence: 99%

Section: Hydrogen Evolution Reaction (Her)mentioning

confidence: 99%

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Corroles at work: a small macrocycle for great applications

2022

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“…Equally important is to approach the cycling potential as close as possible towards the formal potential of the storage material to maximize energy efficiency and to suppress parasitic reactions 4,5,[15][16][17][18][19][20][21] . Soluble redox mediators (RMs) are, therefore, now accepted to be key to achieve these goals and have been studied in a wide variety for Li-O2 cells [3][4][5][11][12][13]18,[21][22][23][24] . First examples have been reported for S electrochemistry 3,[25][26][27] .…”

Section: Redox Mediators Could Catalyse Otherwise Slow and Energy-inefficient Cycling Of Li-s And Li-o2mentioning

confidence: 99%

Sharp kinetic acceleration potentials during mediated redox catalysis of insulators

Cao

Shen

Wang

et al. 2021

Preprint

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Redox mediators could catalyse otherwise slow and energy-inefficient cycling of Li-S and Li-O2 batteries by shuttling electrons/holes between the electrode and the solid insulating storage materials. For mediators to work efficiently they need to oxidize the solid with fast kinetics yet the lowest possible overpotential. Here, we found that when the redox potentials of mediators are tuned via, e.g., Li+ concentration in the electrolyte, they exhibit distinct threshold potentials, where the kinetics accelerate several-fold within a range as small as 10 mV. This phenomenon is independent of types of mediators and electrolyte. The acceleration originates from the overpotentials required to activate fast Li+/e– extraction and the following chemical step at specific abundant surface facets. Efficient redox catalysis at insulating solids requires therefore carefully considering the surface conditions of the storage materials and electrolyte-dependent redox potentials, which may be tuned by salt concentrations or solvents.

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“…In recent years, different redox mediators were studied and received attention due to their ability to stabilize lithium-oxygen batteries [ 5 , 6 , 7 ]. Several redox mediators, including ferrocene [ 8 , 9 , 10 ] and 2,5-di-tert-butyl-1,4-dimethoxybenzene (DBDMB) [ 11 , 12 , 13 , 14 , 15 ], were proposed for the analysis of LIB electrodes.…”

Section: Introductionmentioning

confidence: 99%

Long-Term Stability of Redox Mediators in Carbonate Solvents

2022

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Scanning electrochemical microscopy (SECM) used in the feedback mode is one of the most powerful versatile analytical tools used in the field of battery research. However, the application of SECM in the field of lithium-ion batteries (LIBs) faces challenges associated with the selection of a suitable redox mediator due to its high reactivity at low potentials at lithium metal or lithiated graphite electrodes. In this regard, the electrochemical/chemical stability of 2,5-di-tert-butyl-1,4-dimethoxybenzene (DBDMB) is evaluated and benchmarked with ferrocene. This investigation is systematically carried out in both linear and cyclic carbonates of the electrolyte recipe. Measurements of the bulk current with a microelectrode prove that while DBDMB decomposes in ethyl methyl carbonate (EMC)-containing electrolyte, bulk current remains stable in cyclic carbonates, ethylene carbonate (EC) and propylene carbonate (PC). Ferrocene was studied as an alternative redox mediator, showing superior electrochemical performance in ethyl methyl carbonate-containing electrolytes in terms of degradation. The resulting robustness of ferrocene with SECM is essential for a quantitative analysis of battery materials over extended periods. SECM approach curves depict practical problems when using the decomposing DBDMB for data acquisition and interpretation. This study sheds light towards the use of SECM as a probing tool enabled by redox mediators.

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Controllable and stable organometallic redox mediators for lithium oxygen batteries

Abstract: We introduce corrole-chelated metal complexes as stable redox mediators with adjustable redox potential in lithium–oxygen batteries.

Cited by 18 publications

References 47 publications

Corroles at work: a small macrocycle for great applications

Corroles at work: a small macrocycle for great applications

Sharp kinetic acceleration potentials during mediated redox catalysis of insulators

Long-Term Stability of Redox Mediators in Carbonate Solvents

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