Insight into the Synergistic Effect of N, S Co‐Doping for Carbon Coating Layer on Niobium Oxide Anodes with Ultra‐Long Life

• Published in: Advanced functional materials 2021-05, Vol.31 (19), p.n/a
• Main Authors: Cheng, Xing, Ran, Fanmin, Huang, Yanfei, Zheng, Runtian, Yu, Haoxiang, Shu, Jie, Xie, Ying, He, Yan‐Bing
• Format: Article
• Language: English
• Subjects: Carbon; Coating; density functional theory calculations; Doping; Electrode materials; GeNb 18O 47; Lithium; Mass transfer; Materials science; Nanowires; Niobium oxides; nitrogen/sulfur co‐doped carbon coating; Structural stability; Synergistic effect; synergistic effects
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202100311

Multi‐heteroatoms co‐doped carbon coating can significantly enhance the electronic conductivity and mass transfer rate of the electrode materials due to the synergistic effect. In this study N, S co‐doped carbon coating is introduced on the surface of niobium oxides (GNO@NSC) by using a convenient thiourea evaporation method. Theory calculations and experimental results confirm the synergistic effect of N, S co‐doping in GNO@NSC composite. N, S co‐doping not only enlarges the layer distance of the carbon materials but also leads to more activation sites for lithium storage; meanwhile, the introduction of the co‐doping carbon layer on GNO significantly enhances the bonding interaction with GNO, leading to excellent structural stability and conductivity of the composite. As a result, the GNO@NSC composite possesses excellent structural reversibility, a large specific capacity, and high‐rate performance. GNO@NSC nanowires deliver a highly reversible capacity of 288 mAh g–1 and display excellent cycling stability, and its capacity retention is 78.9% after 6000 cycles at a high current density of 1 A g–1. This study reveals the functional mechanism of N, S co‐doped carbon coating and the origin of performance improvement of niobium oxides, which can be used for reference to design and develop relevant materials. A nitrogen and sulfur co‐doped carbon coating can arouse synergistic effects to boost the electrochemical properties of a composite. Due to the strong bonding interaction, activation sites for lithium storage, large interlayer spacing, and stable structure in the nitrogen and sulfur co‐doped carbon layer, GNO@NSC displays superior rate performance, long cycling performance, and larger lithium‐ion diffusion coefficient.