TY - JOUR
T1 - A volatile redox mediator boosts the long-cycle performance of lithium-oxygen batteries
AU - Yu, Wei
AU - Wu, Xinbin
AU - Liu, Sijie
AU - Nishihara, Hirotomo
AU - Li, Liangliang
AU - Nan, Ce Wen
N1 - Funding Information:
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.
Publisher Copyright:
© 2021
PY - 2021/6
Y1 - 2021/6
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.
KW - Li anode protection
KW - Lithium-oxygen battery
KW - Polymer electrolyte
KW - Redox mediator
KW - Redox shuttling
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U2 - 10.1016/j.ensm.2021.04.003
DO - 10.1016/j.ensm.2021.04.003
M3 - Article
AN - SCOPUS:85104075750
VL - 38
SP - 571
EP - 580
JO - Energy Storage Materials
JF - Energy Storage Materials
SN - 2405-8297
ER -
