A fresh perspective to synthesizing and designing carbon/sulfur composite cathodes using supercritical CO2 technology for advanced Li-S battery cathodes

• Published in: Journal of alloys and compounds Vol. 1008; p. 176691
• Main Authors: Shankar, Lakshmi Shiva, Samaniego Andrade, Samantha K., László, Krisztina, Zalka, Dóra, Nagy, Péter B., Szabados, Márton, Pászti, Zoltán, Balázsi, Katalin, Czigány, Zsolt, Illés, Levente, Kun, Robert
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2024
• Subjects: Li-S battery; Polysulfides; Pore morphology; Supercritical CO2; Surface chemistry; Thermal reduction; Li-S battery; Polysulfides; Pore morphology; Thermal reduction; Supercritical CO2; Surface chemistry
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2024.176691

The morphology and surface chemistry of the sulfur host within lithium-sulfur (Li-S) batteries significantly influence the overall battery performance. To investigate this relationship, we employed a non-toxic heat treatment to produce reduced graphene oxide (rGO) with varying degrees of reduction, resulting in distinct surface chemistries. The physicochemical characteristics and electrochemical properties of four differently reduced GO samples and rGO/sulfur composite cathodes developed with supercritical CO2 technology were examined. Our study established a clear correlation between the specific surface area and porosity of rGO and the electrochemical performance of the corresponding rGO/sulfur composite cathodes. Notably, rGO samples reduced at 350°C (rGO350) exhibited superior discharge capacity and long-term cycling stability compared to those reduced at higher temperatures. This performance enhancement can be attributed to the combination of high surface area, porosity, and an open morphology in rGO350. These findings underscore the importance of optimizing carbon chemistry, microstructure, and cathode synthesis strategies in Li-S batteries. By effectively controlling sulfur loading and distribution within the rGO network, we can enhance active material utilization, boost electronic conductivity, and ensure the long-term stability of rGO/sulfur composite cathodes. Our research suggests that SC-CO2-assisted synthesis offers a promising approach for designing high-performance carbon/sulfur composite cathodes for Li-S batteries. This method provides a versatile platform for tailoring the rGO morphology and surface chemistry, optimizing battery performance. By carefully considering the interplay between these factors, we can unlock the full potential of Li-S batteries for various applications. [Display omitted] •SC-CO2: an excellent hydrophobic solvent that boosts sulfur dissolution and penetration into carbon, improving utilization.•Rapid, green, facile, and highly efficient room temperature synthesis route for high-performance Li-S battery cathodes.•Investigating how adjusting carbon surface chemistry, microstructure, and synthesis method affects cathode performance.•Promising future technology for large-scale electrode synthesis with the least toxicity and energy demands.