Ultrasmall Amorphous Antimony (III) Sulfide Colloidal Nanoparticles for Li-Ion and Na-Ion Batteries with Industrial Potential

Antimony sulfide is a promising negative electrode material for high-energy and high-power density battery systems, particularly lithium-ion and sodium-ion batteries. Its high energy arise from its ability to undergo both conversion and alloying reactions, where multiple cations and electrons react with individual antimony or sulfur atoms. However, these reactions cause substantial volume changes, leading to mechanical stress and electrode degradation. Nanostructuring antimony sulfide has been explored to mitigate these issues, but conventional synthesis methods are often economically prohibitive. To address this challenge, we have developed a scalable room-temperature synthesis process for ultrasmall amorphous antimony sulfide nanoparticles. By controlling short-chain alkyl ligand lengths, we stabilize the nanoparticle surfaces and limit their growth, producing a narrow size distribution of sub-3 nm particles. These nanoparticles, due to their small size and defect-rich, amorphous structure, are well-suited for high-power applications. Small-angle X-ray scattering (SAXS) data further reveal that these nanoparticles form rod-like aggregates, which promote uniform nucleation and size control. Moreover, tuning the ligand length and type enables us to influence particle packing, directly influencing their battery performance even when the ligands are replaced with shorter chain molecules. Importantly, our synthesis method, which is compatible with continuous flow reactors, demonstrates substantial commercial potential due to its economic viability and scalability.