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Lithium-sulfur (Li-S) battery is considered as a promising energy storage system due to its ultrahigh theoretical energy density of 2,600 Wh·kg−1. Redox mediation strategies have been proposed to promote the sluggish sulfur redox kinetics. Nevertheless, the applicability of redox mediators in practical high-energy-density Li-S batteries has seldomly been manifested. In this work, 5,7,12,14-pentacenetetrone (PT) is proposed as an effective redox mediator to promote the sulfur redox kinetics under practical working conditions. A high initial specific discharge capacity of 993 mAh·g−1 is achieved at 0.1 C with high-sulfur-loading cathodes of 4.0 mgS·cm−2 and low electrolyte/sulfur (E/S) ratio of 5 μL·mgS−1. More importantly, practical Li-S pouch cells with the PT mediator realize an actual initial energy density of 344 Wh·kg−1 and cycle stably for 20 cycles wih a high capacity retention of 88%. This work proposes an effective redox mediator and further verifies the redox mediation strategy for practical high-energy-density Li-S batteries.

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Publication history
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Acknowledgements

Publication history

Received: 21 March 2022
Revised: 12 May 2022
Accepted: 26 May 2022
Published: 21 June 2022
Issue date: June 2023

Copyright

© Tsinghua University Press 2022

Acknowledgements

Acknowledgements

This work was supported by the National Key Research and Development Program (No. 2021YFB2400300), Beijing Natural Science Foundation (No. JQ20004), the Natural Scientific Foundation of China (No. 22109007), Scientific and Technological Key Project of Shanxi Province (No. 20191102003), and Beijing Institute of Technology Research Fund Program for Young Scholars. We thank Chen-Xi Bi, Li-Peng Hou, and Dr. Xue-Qiang Zhang for helpful discussion.

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