NiCo2S4/S Composites Used as Cathode Materials in Lithium-Sulfur Batteries with High Performance

Application of lithium-sulfur battery has been limited due to polysulfide dissolution, the insulating nature of sulfur and the volumetric strain produced during charge and discharge process. To improve the performance of Li-S batteries, two kinds of bimetallic sulfides of NiCo 2 S 4 with flaky (F-NiCo 2 S 4 ) and sea urchin-like (S-NiCo 2 S 4 ) structures were synthesized by using simple hydrothermal method, which were used as sulfur carriers in lithium-sulfur batteries and showed excellent electrochemical properties. At 0.2 C, both electrodes of F-NiCo 2 S 4 /S and S-NiCo 2 S 4 /S have high pristine discharge specific capacities of 986 mAh g − 1 and 959 mAh g − 1 . At high current density of 4 C, the F-NiCo 2 S 4 /S electrode still has a high pristine discharge specific capacity of 673 mAh g − 1 and a coulombic efficiency of 97.00%. The specific capacity can remain at 526 mAh g − 1 with a low average attenuation of 0.17% even after 130 cycles. The excellent electrochemical performances of the cathode material can be ascribed to the synergistic effect of tubular morphology, good electrical conductivity and strong adsorption ability of NiCo 2 S 4 matrix for polysulfide. The job provides a new scheme and material for application of lithium-sulfur batteries with high performance.