Catalytic performance of binary transition metal sulfide FeCoS2/rGO for lithium-sulfur batteries

The FeCoS2/rGO was synthesized by a one-step hydrothermal method, which has the advantages of environmental friendliness and low cost. Dense and homogeneous FeCoS2 nanodots are dispersed in the reduced graphene oxide flakes, which is beneficial to improve catalytic activity. Compared with FeS2/rGO, FeCoS2/rGO exhibits much higher initial discharge capacity and much better capacity retention ratio. The lower activation energy and the relatively narrow peak shape and small reduction/oxidation peak spacing show that FeCoS2/rGO have better catalytic activity than FeS2/rGO. It can be also confirmed by first-principles calculation that the adsorption energy of the Fe site (- 1.8334 eV) and the Co site (- 1.7539 eV) on the FeCoS2 surface is better than that of FeS2. So, the synergistic reaction of Fe and Co will adjust microregional electron density and change binding energy to polysulfides.