A volatile redox mediator boosts the long-cycle performance of lithium-oxygen batteries

Wei YU; Xinbin WU; Sijie LIU; Hirotomo NISHIHARA; Liangliang LI; Ce Wen NAN

doi:10.1016/j.ensm.2021.04.003

A volatile redox mediator boosts the long-cycle performance of lithium-oxygen batteries

Wei YU, Xinbin WU, Sijie LIU, Hirotomo NISHIHARA, Liangliang LI^*, Ce Wen NAN

^*Corresponding author for this work

Research output: Journal Publications › Journal Article (refereed) › peer-review

16 Citations (Scopus)

Abstract

To improve the performance of lithium-oxygen (Li-O₂) batteries with an extremely high theoretical energy density, redox mediators (RMs) are usually added to liquid electrolytes to assist with the charge process and reduce the overpotential. However, the shuttle effect and the instability of RMs towards a Li metal anode degrade the cycle performance of Li-O₂ batteries. Herein, we report a volatilization-dissolution strategy to supply RMs by introducing 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) into the O₂ atmosphere (TEMPO-O₂) outside an assembled cell. Due to not directly adding RMs to liquid electrolytes, the parasitic reactions between the Li metal anode and TEMPO, including the TEMPO's shuttle effect, are alleviated. TEMPO-O₂ mediates the formation-decomposition of lithium peroxide (Li₂O₂) in Li-O₂ batteries and shows a uniform catalytic effect towards commercial Li₂O₂. Thanks to the continuous redox mediation of volatile TEMPO and the suppression of the RM's shuttle effect, the Li-O₂ battery demonstrates an ultra-long cycle life of 400 cycles (1600 h) at 250 mA g⁻¹. Our strategy to supply volatile RMs shows a universal adaptability towards different kinds of cathodes and electrolytes, which may trigger broad applications in various gas-involved Li metal batteries.

Original language	English
Pages (from-to)	571-580
Number of pages	10
Journal	Energy Storage Materials
Volume	38
Early online date	6 Apr 2021
DOIs	https://doi.org/10.1016/j.ensm.2021.04.003
Publication status	Published - Jun 2021
Externally published	Yes

Bibliographical note

Publisher Copyright:
© 2021

Funding

This work was financially supported by the Basic Science Center Program of the National Natural Science Foundation of China (Grant no. 51788104), China Postdoctoral Science Foundation (Grant no. 2019M650668), and Tsinghua-Foshan Innovation Special Fund (Grant no. 2018THFS0409). This work was supported in part by “Five-star Alliance” and “NJRC Mater. & Dev.” We are grateful to Dr. Ye Bi and Haijun Yang for their help on EPR measurement.

Keywords

Li anode protection
Lithium-oxygen battery
Polymer electrolyte
Redox mediator
Redox shuttling

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.ensm.2021.04.003

Cite this

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title = "A volatile redox mediator boosts the long-cycle performance of lithium-oxygen batteries",

abstract = "To improve the performance of lithium-oxygen (Li-O2) batteries with an extremely high theoretical energy density, redox mediators (RMs) are usually added to liquid electrolytes to assist with the charge process and reduce the overpotential. However, the shuttle effect and the instability of RMs towards a Li metal anode degrade the cycle performance of Li-O2 batteries. Herein, we report a volatilization-dissolution strategy to supply RMs by introducing 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) into the O2 atmosphere (TEMPO-O2) outside an assembled cell. Due to not directly adding RMs to liquid electrolytes, the parasitic reactions between the Li metal anode and TEMPO, including the TEMPO's shuttle effect, are alleviated. TEMPO-O2 mediates the formation-decomposition of lithium peroxide (Li2O2) in Li-O2 batteries and shows a uniform catalytic effect towards commercial Li2O2. Thanks to the continuous redox mediation of volatile TEMPO and the suppression of the RM's shuttle effect, the Li-O2 battery demonstrates an ultra-long cycle life of 400 cycles (1600 h) at 250 mA g−1. Our strategy to supply volatile RMs shows a universal adaptability towards different kinds of cathodes and electrolytes, which may trigger broad applications in various gas-involved Li metal batteries.",

keywords = "Li anode protection, Lithium-oxygen battery, Polymer electrolyte, Redox mediator, Redox shuttling",

author = "Wei YU and Xinbin WU and Sijie LIU and Hirotomo NISHIHARA and Liangliang LI and NAN, {Ce Wen}",

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AU - YU, Wei

AU - WU, Xinbin

AU - LIU, Sijie

AU - NISHIHARA, Hirotomo

AU - LI, Liangliang

AU - NAN, Ce Wen

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N2 - To improve the performance of lithium-oxygen (Li-O2) batteries with an extremely high theoretical energy density, redox mediators (RMs) are usually added to liquid electrolytes to assist with the charge process and reduce the overpotential. However, the shuttle effect and the instability of RMs towards a Li metal anode degrade the cycle performance of Li-O2 batteries. Herein, we report a volatilization-dissolution strategy to supply RMs by introducing 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) into the O2 atmosphere (TEMPO-O2) outside an assembled cell. Due to not directly adding RMs to liquid electrolytes, the parasitic reactions between the Li metal anode and TEMPO, including the TEMPO's shuttle effect, are alleviated. TEMPO-O2 mediates the formation-decomposition of lithium peroxide (Li2O2) in Li-O2 batteries and shows a uniform catalytic effect towards commercial Li2O2. Thanks to the continuous redox mediation of volatile TEMPO and the suppression of the RM's shuttle effect, the Li-O2 battery demonstrates an ultra-long cycle life of 400 cycles (1600 h) at 250 mA g−1. Our strategy to supply volatile RMs shows a universal adaptability towards different kinds of cathodes and electrolytes, which may trigger broad applications in various gas-involved Li metal batteries.

AB - To improve the performance of lithium-oxygen (Li-O2) batteries with an extremely high theoretical energy density, redox mediators (RMs) are usually added to liquid electrolytes to assist with the charge process and reduce the overpotential. However, the shuttle effect and the instability of RMs towards a Li metal anode degrade the cycle performance of Li-O2 batteries. Herein, we report a volatilization-dissolution strategy to supply RMs by introducing 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) into the O2 atmosphere (TEMPO-O2) outside an assembled cell. Due to not directly adding RMs to liquid electrolytes, the parasitic reactions between the Li metal anode and TEMPO, including the TEMPO's shuttle effect, are alleviated. TEMPO-O2 mediates the formation-decomposition of lithium peroxide (Li2O2) in Li-O2 batteries and shows a uniform catalytic effect towards commercial Li2O2. Thanks to the continuous redox mediation of volatile TEMPO and the suppression of the RM's shuttle effect, the Li-O2 battery demonstrates an ultra-long cycle life of 400 cycles (1600 h) at 250 mA g−1. Our strategy to supply volatile RMs shows a universal adaptability towards different kinds of cathodes and electrolytes, which may trigger broad applications in various gas-involved Li metal batteries.

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KW - Polymer electrolyte

KW - Redox mediator

KW - Redox shuttling

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A volatile redox mediator boosts the long-cycle performance of lithium-oxygen batteries

Abstract

Bibliographical note

Funding

Keywords

UN SDGs

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