Indirect growth of mesoporous Bi@C core-shell nanowires for enhanced lithium-ion storage.

In this paper, we propose a facile synthetic strategy for uniform bismuth@carbon (Bi@C) core-shell nanowires, which are prepared via controlled pyrolysis of Bi2S3@glucose-derived carbon-rich polysaccharide (GCP) nanowires under an inert atmosphere. Carbonization of GCP and pyrolysis of Bi2S3 into Bi occur at 500 °C and 600 °C, respectively, which increase the specific surface area and the pore volume of the nanowires, thus allowing accommodation of more lithium ions. Meanwhile, the carbon shell serves as a buffer layer to relieve large volume expansion-contraction during the electrochemical alloy formation, and can also efficiently reduce the aggregation of the nanowires. As a proof-of-concept, the Bi@C core-shell nanowire anodes manifest enhanced cycling stability (408 mA h g(-1) after 100 cycles at a current density of 100 mA g(-1)) and rate capacity (240 mA h g(-1) at a current density of 1 A g(-1)), much higher than pure bismuth microparticles and corresponding Bi2S3@C nanowires.