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 processes 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.