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Benefiting from the distinctive ordering degree and local microstructure characteristics, hard carbon (HC) is considered as the most promising anode for sodium-ion batteries (SIBs). Unfortunately, the low initial Coulombic efficiency (ICE) and limited reversible capacity severely impede its extensive application. Here, a homogeneous curly graphene (CG) layer with a micropore structure on HC is designed and executed by a simple chemical vapor deposition method (without catalysts). CG not only improves the electronic/ionic conductivity of the hard carbon but also effectively shields its surface defects, enhancing its ICE. In particular, due to the spontaneous curling structural characteristics of CG sheets (CGs), the micropores (≤ 2 nm) formed provide additional active sites, increasing its capacity. When used as a sodium-ion battery anode, the HC-CG composite anode displayed an outstanding reversible capacity of 358 mAh·g−1, superior ICE of 88.6%, remarkable rate performance of 145.8 mAh·g−1 at 5 A·g−1, and long cycling life after 1000 cycles with 88.6% at 1 A·g−1. This work provides a simple defect/microstructure turning strategy for hard carbon anodes and deepens the understanding of Na+ storage behavior in the plateau region, especially on the pore-filling mechanism by forming quasi-metallic clusters.


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Growing curly graphene layer boosts hard carbon with superior sodium-ion storage

Show Author's information Minghao Song1,§Qiang Song1,§Tao Zhang1Xiaomei Huo2Zezhou Lin3Zhaowen Hu1Lei Dong1Ting Jin1,3Chao Shen1( )Keyu Xie1( )
State Key Laboratory of Solidification Processing, Center for Nano Energy Materials, School of Materials Science and Engineering, Northwestern Polytechnical University and Shaanxi Joint Laboratory of Graphene (NPU), Xi’an 710072, China
Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Southwest University of Science and Technology, Mianyang 621010, China
Department of Applied Physics and Research Institute for Smart Energy, The Hong Kong Polytechnic University, Hong Kong 999077, China

§ Minghao Song and Qiang Song contributed equally to this work.

Abstract

Benefiting from the distinctive ordering degree and local microstructure characteristics, hard carbon (HC) is considered as the most promising anode for sodium-ion batteries (SIBs). Unfortunately, the low initial Coulombic efficiency (ICE) and limited reversible capacity severely impede its extensive application. Here, a homogeneous curly graphene (CG) layer with a micropore structure on HC is designed and executed by a simple chemical vapor deposition method (without catalysts). CG not only improves the electronic/ionic conductivity of the hard carbon but also effectively shields its surface defects, enhancing its ICE. In particular, due to the spontaneous curling structural characteristics of CG sheets (CGs), the micropores (≤ 2 nm) formed provide additional active sites, increasing its capacity. When used as a sodium-ion battery anode, the HC-CG composite anode displayed an outstanding reversible capacity of 358 mAh·g−1, superior ICE of 88.6%, remarkable rate performance of 145.8 mAh·g−1 at 5 A·g−1, and long cycling life after 1000 cycles with 88.6% at 1 A·g−1. This work provides a simple defect/microstructure turning strategy for hard carbon anodes and deepens the understanding of Na+ storage behavior in the plateau region, especially on the pore-filling mechanism by forming quasi-metallic clusters.

Keywords: sodium-ion battery, hard carbon, curly graphene, pore-filling mechanism, superior sodium-ion storage

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Publication history
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Acknowledgements

Publication history

Received: 07 December 2022
Revised: 15 January 2023
Accepted: 30 January 2023
Published: 05 March 2023
Issue date: July 2023

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© Tsinghua University Press 2023

Acknowledgements

The authors acknowledge the financial support of this work by the National Natural Science Foundation of China (No. 52202302), National Natural Science Foundation of Shaanxi (Nos. 2019JLZ-01 and 2022KXJ-146), the Fundamental Research Funds for the Central Universities (No. 3102019JC005), and the Youth Innovation Team of Shaanxi Universities and ND Basic Research Funds (No. G2022WD).

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