Carbon-Coated Te-Doped Bi₂Se₃ as a Topological Quantum Anode Material for Sodium-Ion Batteries

Abstract

Sodium-ion batteries (SIBs) are increasingly investigated as cost-effective alternatives to lithium-ion systems for large-scale energy storage; however, the development of stable and conductive anode materials remains a major challenge. In this work, tellurium-doped bismuth selenide (Te-doped Bi₂Se₃) was synthesized and further modified with Super P conductive carbon to improve its sodium-storage behavior. The phase formation and structural retention of the active material were examined using X-ray diffraction, while elemental mapping and energy-dispersive X-ray spectroscopy verified the incorporation of Te and the presence of carbon in the modified sample. Thermogravimetric analysis showed that the material remained thermally stable up to approximately 500°C. Electrochemical testing in sodium half-cells revealed that the uncoated Te-doped Bi₂Se₃ electrode delivered stable capacities of about 150 mAh g⁻¹ at 20 mA g⁻¹ and 110 mAh g⁻¹ at 40 mA g⁻¹. After carbon modification, the corresponding capacities increased to approximately 250 mAh g⁻¹ and 175 mAh g⁻¹, respectively. Cyclic voltammetry further indicated improved redox reversibility and more stable peak currents for the carbon-modified electrode. These results suggest that carbon-coated/composite Te-doped Bi₂Se₃ is a promising anode candidate for SIBs, with carbon modification providing improved conductivity, enhanced reaction reversibility, and better rate performance.