Bi2S3 nanorods rich in sulfur vacancies for hybrid supercapacitors

In this study, we presented a mild hydrothermal method for preparing Bi 2 S 3 nanorods with varying bismuth-to‑sulfur ratios and systematically investigated the influence of these different ratios on its supercapacitor's performance. We adjusted the sulfur vacancy concentration in Bi 2 S 3 by different bismuth to sulfur ratios and found that the concentration of sulfur vacancy in Bi 2 S 3 reached a maximum at the bismuth to sulfur ratio of 1:12. At a Bi:S molar ratio of 1:12, the synthesized Bi 2 S 3 –3 demonstrated a high discharge capacity of 233.1C g −1 under 1 A g −1 current density. Notability, Bi 2 S 3 –3 maintains 67.4 % capacity retention after 10,000 cycles at 10 A g −1 , demonstrating exceptional cycling stability. When configured in a hybrid supercapacitor (Bi 2 S 3 –3//AC), the device achieves energy densities and power densities of 23.78 Wh kg −1 and 798.58 W kg −1 , respectively, showcasing its practical energy storage capabilities. Even at a current density of 10 A g −1 , the system maintained a capacity retention rate of 87.5 % and a coulomb efficiency of 99.1 % after 10,000 cycles of charge and discharge. The improved performance of the supercapacitor can be attributed to the introduction of more sulfur vacancies, which increases the number of active sites within the Bi 2 S 3 framework, significantly improves the charge transfer dynamics, and promotes the charge transfer between Bi 2 S 3 and electrolyte. This work provides new insights into improving the performance of supercapacitors through defect engineering modification of transition metal sulfides.