A novel crosslinked sulfur-containing polymer cathode material for high-performance lithium-sulfur batteries

The shuttle effect of polysulfide has been the main reason for the rapid capacity decay of lithium-sulfur batteries during cycling, which hinders their large-scale application. In present work, a novel sulfur-containing polymer, S-Span9-MDx, was synthesized by polymerization of sulfur, Span 80 and cross-linking agent 4, 4′ -methylene bis (phenyl isocyanate) (MD) at different mass ratios. Wherein, the battery with S-Span9-MD2 as cathodes exhibits the best electrochemical properties, achieved a high initial capacity of 1409 mAh g−1 at 0.1C, with a sulfur utilization of 84.3% and a capacity retention of 67.1% after 100 cycles. Furthermore, S-Span9-MD2 cathode delivered an initial capacity of 862 mAh g−1 at a high current density of 0.5C, after a long cycle of 200 cycles, the discharge capacity of S-Span9-MD2 electrode remained at 595 mAh g−1, which translated into a small capacity decay of 0.155% per cycle. These results indicated that the battery with sulfur-containing polymer S-Span9-MD2 exhibited excellent electrochemical performances, which would provide a feasible strategy for polysulfide trapping to boost the cycle stability of lithium-sulfur battery.