Synthesis of Bi2S3/carbon nanocomposites as anode materials for lithium-ion batteries

Metal sulfides such as Bismuth sulfide(Bi2 S3) hold immense potential to be promoted as anode materials for lithium-ion batteries(LIBs),owing to their high theoretical gravimetric and volumetric capacities.However,the poor electrical conductivity and volume expansion during cycling hinder the practical applications of Bi2 S3.In this work,we used pyrrole and glucose as carbon source to design the surface carbon coating on the surface of Bi2 S3 particles,to improve the structural stability of Bi2 S3.Two composite materials were synthesized-Bi2 S3 coated with nitrogen doped carbon(Bi2 S3@NC),and Bi2 S3 coated with carbon(Bi2 S3@C).When used as anode active materials,both Bi2 S3@NC and Bi2 S3@C showed improved performance compared to Bi2 S3,which confirms surface carbon coating as an effective and scalable way for the modification of Bi2 S3 material.The electrode based on Bi2 S3@NC materials demonstrated higher performance than that of Bi2 S3@C,with an initial discha rge capacity of 1126.5 mA h/g,good cycling stability(500 mA h/g after 200 cycles at 200 mA/g) and excellent rate capability.Finally,Li storage and migration mechanisms in Bi2 S3 are revealed using first principle density functional theory calculations.