Trace sulfurization engineering enabling improved initial coulombic efficiency and high reversible sodium-ion storage in bismuth-based anode

Bismuth (Bi) anodes have been widely investigated for potential application in sodium-ion batteries (SIBs) due to their ultrahigh theoretical volumetric capacity (3800 mAh cm(-3)) and suitable sodiation potential (0.5-0.7 V). Unfortunately, either Bi or Bi-based compounds still face tricky challenges of unsat- isfying reversible capacity (<350 mAh g(-1)) and inferior initial Coulombic efficiency (ICE, <70%). Herein, a controllable trace-sulfurization strategy is proposed to address these challenges by developing a yolk- shell Bi/Bi2S3 heterostructure encapsulated within S-doped carbon shells (TS-Bi/C). This approach strate- gically incorporates a trace amount of high-capacity BiS, phase with metallic Bi, consequently building regional Bi/Bi,S, heterointerfaces for enhancing interfacial charge transfer and sodium storage reversibil- ity. Moreover, a thin and homogeneous solid electrolyte film (similar to 5 nm) was formed on the surface of TS-Bi/C during the initial discharge-charge process. These merits result in an approximate 30% increase in ICE of 'TS-Bi/C (87.4%) compared to pure Bi/C (57.6%) when employed as anodes in SIBs, together with boosted harge capacity of 462.3 mAh g(-1) at 0.1 Ag-1 and high rate capability of 382.4 mAh g(-1) at 10 Ag-1 Importantly, as compared to both Bi/C and Bi2S3 /C counterparts, TS-Bi/C can deliver superior volumetric capacity as high as 1553 mAh cm(-3) owing to its considerable tap density of 3.43 g cm(-3) (c) 2024 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, Al training, and similar technologies.