Sulfur-rich copolymers were synthesized via inverse vulcanization to create electroactive cathode materials for lithium-sulfur battery applications. These materials exhibit enhanced capacity retention (1005 mAh/g at 100 cycles) and extended battery lifetimes over 500 cycles at a C/10 rate. The inverse vulcanization method enables facile variation of sulfur composition into copolymer materials. Structure-property correlations between the sulfur composition, cathode microstructure and electrochemical properties are used to determine optimal materials for Li-S batteries. The incorporation of organosulfur species into active cathodes improves their mechanical properties, reduces compositional heterogeneity, and inhibits solid Li2S discharge products during cycling. These mechanisms combine to reduce cathode damage which leads to improved long term battery performance.