Effect of Local Atomic Structure on Sodium Ion Storage in Hard Amorphous Carbon

• Published in: Nano letters Vol. 21; no. 15; pp. 6504 - 6510
• Main Authors: Han, Jiuhui, Johnson, Isaac, Lu, Zhen, Kudo, Akira, Chen, Mingwei
• Format: Journal Article
• Language: English
• Published: American Chemical Society 11.08.2021
• Subjects: local order; sodium storage; sodium-ion batteries; hard carbon; amorphous materials
• ISSN: 1530-6984; 1530-6992; 1530-6992
• DOI: 10.1021/acs.nanolett.1c01595

The fundamental understanding of sodium storage mechanisms in amorphous carbon is essential to develop high-performance anode materials for sodium-ion batteries. However, the intrinsic relation between the structure of amorphous carbon and Na+ storage remains to be debated due to the difficulty in controlling and characterizing the local atomic configurations of amorphous carbon. Here we report quantitative measurements of Na+ storage in a low-temperature dealloyed hard carbon with a tunable local structure from completely disordered micropores to gradually increased graphitic order domains. The structure-capacity-potential correlation not only verifies the disputing “adsorption–intercalation” mechanisms, i.e., Na+ intercalation into local graphitic domains for the low-voltage plateaus and adsorption in fully disordered carbon for the sloping voltage profiles, but also unveils a new mechanism of Na+ adsorption on defective sites of graphitic carbon in the medium-potential sloping region. The quantitative investigations provide essential insights into the reaction mechanisms of Na+ with amorphous carbon for designing advanced sodium-ion battery anodes.