A sulfur-rich copolymer has been prepared by utilizing two eco-friendly sources, squalene and sulfur. Chemical confinement of sulfur with squalene molecules can effectively suppress the active materials dissolution. The sulfur-rich copolymer was composited with 3D graphene-CNT network. The well-structured porous cathode can deliver an excellent electrochemical performance for lithium-sulfur battery cathodes. Display omitted Lithium-sulfur (Li-S) batteries with high theoretical energy density and low cost are considered a promising energy storage system. However, great challenges still remain in achieving high sulfur loading and long cycle life. Herein we report a well-designed sulfur-rich copolymer@ 3D graphene-carbon nanotubes (G-CNT) network cathode for high-performance Li-S batteries. The sulfur-rich copolymer (87.29% sulfur) synthesised by inverse vulcanization between two eco-friendly sources, sulfur and squalene, can greatly suppress the dissolution of sulfur and polusulfides due to the chemical confinement from the crosslinking of polysulfur chains with the squalene molecules. The interlinked Sp2 G-CNT network can not only further enhance the polysulfide entrapment capability, but also provide the composite with an 3D electrical conductive path as well as an eminent mechanical resilience towards the huge volume change of sulfur. The as-developed cathode can deliver a high specific capacity of 1265 mAh g−1 at 0.2C with excellent rate performance and cycling stability (782 mAh g−1 at after 300 cycles at 1C).