Boosting the Initial Coulombic Efficiency of Bi2s3-Based Anode for Practical Sodium-Ion Batteries

Abstract

Bi2S3 is a promising anode candidate for sodium-ion batteries (SIBs) due to its high capacity and cost-effectiveness. However, the severe volume expansion that occurs during sodiation/desodiation process results in inferior cycling stability and low initial Coulombic efficiency (ICE), which hinders its further development. Herein, we deposited Bi2S3 nanorods onto lignite-derived carbon skeleton (Bi2S3/LC) via a solvothermal method for high performance anode. Experimental studies combined with theoretical calculation reveal that the presence of LC can enhance the porosity and sulfur vacancies of Bi2S3, boost the adsorption ability and reversibility of its sodiation intermediate NaBiS2 for Na+. Additionally, incorporating fluoroethylene carbonate (FEC) into the ester-based electrolyte enables the in-situ formation of a conformal and ultra-thin NaF-rich solid electrolyte interphase (SEI) on the anode surface and improves its structural stability. These advancements endow Bi2S3/LC anode displays an excellent ICE (up to 93.2% at 0.1 A g-1), rapid sodium storage capability (388.8 mAh g-1 at 8 A g-1), and impressive cycle stability (up to 96.3% capacity retention after 1000 cycles at 10 A g-1). The exceptional Na+ storage capability of Bi2S3/LC anode also enables the assemable SIB full cell to demonstrate impressive rate capability and cycling stability, underscoring their potential for high-performance practical applications.

Keywords: Initial Coulomb efficiency, Nanorod-like Bi2S3, sodium-ion batteries, Anode