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

Abstract

Metal sulfides such as Bismuth sulfide (Bi2S3) 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 Bi2S3. In this work, we used pyrrole and glucose as carbon source to design the surface carbon coating on the surface of Bi2S3 particles, to improve the structural stability of Bi2S3. Two composite materials were synthesized – Bi2S3 coated with nitrogen doped carbon (Bi2S3@NC), and Bi2S3 coated with carbon (Bi2S3@C). When used as anode active materials, both Bi2S3@NC and Bi2S3@C showed improved performance compared to Bi2S3, which confirms surface carbon coating as an effective and scalable way for the modification of Bi2S3 material. The electrode based on Bi2S3@NC materials demonstrated higher performance than that of Bi2S3@C, with an initial discharge 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 Bi2S3 are revealed using first principle density functional theory calculations.