Modifying rGO with multicarbonyl organic molecule for lithium sulfur batteries with high performance

The "shuttle effect" of polysulfide in the cycling process seriously hinders the practical application of lithium-sulfur batteries. Herein, a perylene-based organic molecule with multiple carbonyl groups (PN) was introduced to modify rGO and form a PN-rGO composite network. PN with large conjugated planar structure is potential to be highly distributed throughout the electrode. The large specific surface area of rGO provides a substrate for PN molecules and could avoid their aggregation. Moreover, PN-rGO can provide a rapid and continuous transporting path for lithium ions and electrons, thus improving conductivity and accelerating the electrochemical dynamics of the battery. At the same time, the carbonyl groups in PN can effectively adsorb polysulfide through SO interaction, and the shuttle effect of polysulfide could be alleviated. A high discharge specific capacity of 1071 mAh g−1 is retained after 200 cycles at 0.2C. In addition, the composite showed a higher rate performance of 589 mAh g−1 at 5C, compared to pristine rGO (283 mAh g−1). This work demonstrates that the rational design of organic small molecule to modify carbon materials is potential to inhibit the shuttle effect as well as to acquire stable cathode material. Our work may provide a foundation for the future design of functionalized organic molecules as energy storage materials.