▎ 摘　　要

Lithium-sulfur batteries are considered as a promising candidate for the next-generation high energy density storage devices. However, they are still hindered by serious capacity decay on cycling caused by the dissolution of redox intermediates. Here, we designed a unique structure with polypyrrole (ppy) inserting into the graphene oxide (GO) sheet for accommodating sulfur. Such a sulfur host not only exhibits a good electronic and ionic conductivity, but also can suppress polysulfide dissolution effectively. With this advanced design, the composite cathode showed a high specific capacity of 548.4 mA.h.g(-1) at 5.0 C. A stable Coulombic efficiency of similar to 99.5% and a capacity decay rate as low as 0.089% per cycle along with 300 cycles at 1.0 C were achieved for composite cathodes with 78 wt.% of S. Besides, the interaction mechanism between PPy and lithium polysulfides (LPS) was investigated by density-functional theory (DFT), suggesting that only the polymerization of N atoms can bind strongly to Li ions of LPS rather than single N atoms. The 3D structure GO-PPy host with high conductivity and excellent trapping ability to LPS offered a viable strategy to design high-performance cathodes for Li-S batteries.