Interfacial Engineering of a Bi/SnS Heterojunction with a Built-in Electric Field toward High-Capacity Sodium-Ion...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Tin sulfide (SnS) is a promising high-capacity anode material for sodium-ion batteries.
• Key challenges include significant volume expansion and sluggish reaction kinetics during cycling.
• Effective strategies are needed to enhance SnS anode performance and stability.

Purpose of the Study:

• To engineer a novel Bi/SnS heterojunction to address the limitations of SnS anodes.
• To investigate the role of the heterointerface in improving electrochemical performance.
• To provide insights into heterointerface engineering for next-generation energy storage.

Main Methods:

• Fabrication of a hydrangea-like Bi/SnS heterojunction structure.
• Utilizing theoretical calculations (e.g., work function analysis) to understand interfacial phenomena.
• Electrochemical testing including rate capability, cycling stability, and initial Coulombic efficiency measurements.

Main Results:

• Theoretical calculations confirmed electron transfer from Bi to SnS, creating a built-in electric field (BIEF).
• The BIEF effectively enhances charge transfer kinetics and reduces the Na+ diffusion barrier to 0.12 eV.
• The Bi/SnS anode achieved high initial Coulombic efficiency (92%), excellent rate capability (400 mAh g-1 at 20 A g-1), and remarkable cycling stability (79.21% retention after 3000 cycles).

Conclusions:

• The Bi/SnS heterojunction successfully mitigates volume expansion and improves kinetics in sodium-ion battery anodes.
• The built-in electric field at the Bi/SnS interface is crucial for enhanced electrochemical performance.
• This work offers fundamental insights for designing advanced heterointerface materials for efficient energy storage applications.