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

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.