A linear molecule sulfur-rich organic cathode material for high performance lithium–sulfur batteries

Abstract

Organic compounds containing S–S bonds can act as alternative cathode materials for lithium-sulfur battery to achieve high electrochemical performance through warding off the polysulfide shuttle. But most of them are less competitive due to the limited theoretical capacity and complicated synthetic process. Herein, we propose a linear molecule sulfur-rich organic material as sulfur cathode, which synthesized by prolonging the linear S–S chain in the commercial tetramethylthiuram disulfide (TMTD). The obtained tetramethylthiuram disulfide-sulfur (TMTD-S) cathode material not only possesses the unique linear structure to maintain its cycling stability, but also have a high active sulfur content to ensure its lithium storage capacity. Thus, the TMTD-S compound delivers an initial capacity of 685 mAh g−1 at 0.2C (1 C = 1061 mAh g−1) and maintains the capacity at 540 mAh g−1 after 200 cycles. Furthermore, when we improve the conductive of TMTD-S cathode material by Ketjen Black agent and carbon cloth current collector, it delivers higher initial capacity as high as 1054 mAh g−1 and retains 930 mAh g−1 after 100 cycles even at a high current density of 0.5 C and high mass loading of 1.8 mg cm−2.