Facile Aqueous Synthesis of Ultrathin Sb ₂ O ₃ Nanobelts for High-Performance Sodium-Ion Battery Anodes

Low-dimensional Sb2O3 holds great promise as an anode material for sodium-ion batteries (SIBs), but its scalable synthesis remains a challenge. Here, we report a green hydrothermal approach in surfactant-free pure water to fabricate ultrathin Sb2O3 nanobelts (NBs) via a multistage growth mechanism: (i) ultrasonic exfoliation of bulk Sb into quantum dots, (ii) dissolved oxygen-driven oxidation and self-assembly into nanoclusters, and (iii) temperature-controlled phase selection, yielding orthorhombic NBs at 80 °C with respect to cubic nanosheets at room temperature. This method is observed to achieve a mass conversion rate of over 32% for the target NBs with controlled dimensions. Furthermore, the Sb2O3 NBs exhibit an ultrathin thickness (<40 nm) along the [100] orientation, effectively mitigating volume expansion during cycling. Such an anode material delivers a discharge capacity of 443.1 mAh·g–1 at 0.1 A·g–1 over 150 cycles, demonstrating an outstanding long-term cyclability. The current work provides a scalable and eco-friendly synthesis strategy for low-dimensional Sb2O3 nanostructures, offering new insights into their application in SIBs and other energy storage devices.