Hot-injected ligand-free SnTe nanoparticles: a cost-effective route to flexible symmetric supercapacitors

In this study, we report a novel approach for synthesizing tin telluride (SnTe) nanostructures using a hot injection method with water as the solvent, a significant departure from traditional organic solvents. This water-based synthesis not only aligns with green chemistry principles but also offers superior control over nucleation and growth, leading to SnTe nanostructures with well-defined morphologies and sizes. These nanostructures were thoroughly characterized, confirming their crystal structure, surface composition, and morphology. Electrochemical three-electrode supercapacitive testing revealed that the SnTe-based supercapacitors exhibit a specific capacitance of 602 F g⁻¹ with excellent rate capability and a capacitance retention of 89% after 5000 cycles. Furthermore, we developed a flexible all-solid-state symmetric supercapacitor with SnTe nanoparticles and PVA–NaClO₄ gel polymer electrolyte, which achieved an energy density of 17.8 Wh kg⁻¹ and a power density of up to 3.1 kW kg⁻¹, surpassing previously reported SnTe-based devices. Additionally, the supercapacitor demonstrated excellent cycling stability, retaining 96.56% of its initial capacitance after 5000 charge–discharge cycles at 4 A g⁻¹ with a coulombic efficiency of 95.76%. This research demonstrates the potential of SnTe as a high-performance electrode material for supercapacitors and underscores the significance of our novel, environmentally friendly synthesis approach in advancing energy storage technologies.