Investigation on Fabrication of Reduced Graphene Oxide-Sulfur Composite Cathodes for Li-S Battery via Hydrothermal and Thermal Reduction Methods

• Main Authors: Zhiqi Li, Hao Sun, Yuepeng Pang, Mingming Yu, Shiyou Zheng
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Materials
• Subjects: reduced graphene oxide; sulfur; composite; battery; Li-S battery
• Online Access: https://www.mdpi.com/1996-1944/14/4/861

Lithium-sulfur (Li-S) battery is considered one of the possible alternatives for next-generation high energy batteries. However, its practical applications are still facing great challenges because of poor electronic conductivity, large volume change, and polysulfides dissolution inducing “shuttle reaction” for the S cathode. Many strategies have been explored to alleviate the aforementioned concerns. The most common approach is to embed S into carbonaceous matrix for constructing C-S composite cathodes. Herein, we fabricate the C-S cathode reduced graphene oxide-S (rGO-S) composites via one step hydrothermal and in-situ thermal reduction methods. The structural features and electrochemical properties in Li-S cells of the two type rGO-S composites are studied systematically. The rGO-S composites prepared by one step hydrothermal method (rGO-S-HT) show relatively better comprehensive performance as compared with the ones by in-situ thermal reduction method (rGO-S-T). For instance, with a current density of 100 mA g⁻¹, the rGO-S-HT composite cathodes possess an initial capacity of 1290 mAh g⁻¹ and simultaneously exhibit stable cycling capability. In particular, as increasing the current density to 1.0 A g⁻¹, the rGO-S-HT cathode retains a reversible capacity of 582 mAh g⁻¹ even after 200 cycles. The enhanced electrochemical properties can be attributed to small S particles uniformly distributed on rGO sheets enabling to significantly improve the conductivity of S and effectively buffer large volume change during lithiation/delithiation.