In Situ Transformation of LDH into NiCo₂S₄-NiS₂ Nano-heterostructures on Hollow Carbon Boxes to Promote Sulfur Electrochemistry for High-Performance Lithium–Sulfur Batteries

Abstract

The practical application of lithium–sulfur batteries is hindered by slow redox reaction kinetics and serious lithium polysulfide (LiPS) migration, especially in the scene of high sulfur loading and a lean electrolyte. A strategy has been proposed to catalyze the liquid–solid conversion of lithium polysulfides in “sealed” nanoboxes with the NiCo2S4-NiS2 nano-heterostructures, in which both LiPS migration and retardation reaction kinetics can be handled simultaneously. The design of hollow carbon boxes can alleviate the volume expansion during the cyclic process. Meanwhile, the NiCo2S4-NiS2 nano- heterostructures on hollow carbon boxes can effectively adsorb LiPS and catalyze their quick conversion, which have a synergistic enhancement effect on inhibiting the shuttle effect. Ultimately, this design achieves decent battery performance with a high specific capacity of 1207 mAh g–1 at 0.2C and long-term cyclability with a capacity retention of 60.23% after 450 cycles at 1C as well as a high initial areal capacity of 6.09 mAh cm–2 with a loading of 5 mg cm–2 under an electrolyte/sulfur ratio of 8.0 mL g–1.