Bi nanoparticles confined in N,S co-doped carbon nanoribbons with excellent rate performance for sodium-ion batteries

Bismuth (Bi) has emerged as a promising candidate for sodium-ion battery anodes because of its unique layered crystal structure, superior volumetric capacity, and high theoretical gravimetric capacity. However, the large volume expansion and severe aggregation of Bi during the alloying/dealloying reactions are extremely detrimental to cycling stability, which seriously hinders its practical application. To overcome these issues, we propose an effective synthesis of composite materials, encapsulating Bi nanoparticles in N,S co-doped carbon nanoribbons and composites with carbon nanotubes (N,S-C@Bi/CNT), using Bi2S3 nanobelts as templates. The uniform distribution of Bi nanoparticles and the structure of carbon nanoribbons can reduce the diffusion path of ions/electrons, efficiently buffer the large volume change and prevent Bi from aggregating during cycles. As expected, the N,S-C@Bi/CNT electrode shows superior sodium storage performance in half cells, including a high specific capacity (345.3 mA h g(-1) at 1.0 A g(-1)), long cycling stability (1000 cycles), and superior rate capability (336.0 mA h g(-1) at 10.0 A g(-1)).

Automated summary

To overcome the challenges posed by volume expansion and aggregation of Bismuth (Bi) during the alloying/dealloying reactions in sodium-ion batteries, a composite material called N,S-C@Bi/CNT was synthesized by encapsulating Bi nanoparticles in N,S co-doped carbon nanoribbons and composites with carbon nanotubes. This composite material exhibited a uniform distribution of Bi nanoparticles and a structure that reduced diffusion path and prevented aggregation. Experimental results showed that the N,S-C@Bi/CNT electrode displayed superior sodium storage performance, including high specific capacity, long cycling stability, and excellent rate capability.