Cubic pyrite nickel sulfide nanospheres decorated with Ketjen black@ sulfur composite for promoting polysulfides redox kinetics in lithium-sulfur batteries

Lithium polysulfides shuttle effect and their sluggish redox kinetics have seriously affected the development of lithium-sulfur batteries. To solve these issues, we have designed cubic pyrite-structure NiS2 nanospheres modification of Ketjen black@sulfur (NiS2/KB@S) composite as cathode materials for lithium-sulfur batteries. The NiS2 nanospheres have a positive effect on the adsorption and catalysis performance of the lithium polysulfides, which further facilitates the redox kinetics. Consequently, the NiS2/KB@S cathode with 3.1 mg cm-2 sulfur loading attains a discharge capacity of 869 mAh g-1 at 0.5 C and reversible capacity is 461 mAh g(-1) after 500 cycles. Even at high sulfur loading of 5.3 mg cm-2, the NiS2/KB@S electrode still delivers a high initial area capacity of 4.82 mAh cm-2 at 0.2 C with capacity retention capacity of 3.74 mAh cm(-2) after 120 cycles. The cyclic and rate properties of NiS2/KB@S are greatly improved over that of KB@S. The results suggest that multifunction cubic pyrite-structure NiS2 nanospheres that anchors effectively and catalysis is beneficial to the large-scale application for lithium-sulfur batteries. (C) 2022 Elsevier B.V. All rights reserved.