Exploring Sodium‐Ion Storage Mechanism in Hard Carbons with Different Microstructure Prepared by Ball‐Milling Method

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2018-09, Vol.14 (39), p.e1802694-n/a
• Main Authors: Lu, Haiyan, Ai, Fangxing, Jia, Yanlong, Tang, Chunyan, Zhang, Xinhe, Huang, Yunhui, Yang, Hanxi, Cao, Yuliang
• Format: Article
• Language: English
• Subjects: Anodes; ball milling; Carbon; hard carbon; Ion storage; mechanism; micro–nanostructure; Nanotechnology; Sodium; Sodium-ion batteries; Storage batteries
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201802694

Hard carbon is considered as one of the most promising anodes in sodium‐ion batteries due to its high capacity, low cost, and abundant resources. However, the available capacity and low initial Coulombic efficiency (ICE) limits the practical application of hard carbon anode. This issue results from the unclear understanding of the Na+ storage mechanism in hard carbon. In this work, a series of hard carbons with different microstructures are synthesized through an “up to down” approach by using a simple ball‐milling method to illustrate the sodium‐ion storage mechanism. The results demonstrate that ball‐milled hard carbon with more defects and smaller microcrystalline size shows less low‐potential‐plateau capacity and lower ICE, which provides further evidence to the “adsorption–insertion” mechanism. This work might give a new perspective to design hard carbon material with a proper structure for efficient sodium‐ion storage to develop high‐performance sodium‐ion batteries. The mechanism of Na+ storage into hard carbon is investigated using ball‐milled hard carbon, which demonstrates that ball‐milled hard carbon with more defects and smaller microcrystalline size shows less low‐potential‐plateau capacity and lower initial Coulombic efficiency, providing further evidence to the “adsorption–insertion” mechanism.