Abstract
Abstract This study successfully developed a porous NiS nanosheet sulfur carrier based on MOF derivatives through a multi-level structural design strategy, thereby significantly improving the electrochemical performance of lithium–sulfur batteries. Single-crystal β-Ni(OH)2 nanosheets synthesized by the urea hydrothermal method were used as templates to construct Ni(OH)2@MOF-74 heterostructures through in situ coordination reactions. Then, a NiS nanosheet carrier with graded pores was prepared through a precisely controlled carbonization sulfurization process. This carrier exhibits triple functional advantages: the MOF-derived three-dimensional conductive carbon network (conductivity > 10–2 S/cm) ensures efficient electron transfer; the exposed NiS (101) crystal plane achieves strong chemical anchoring and efficient catalytic conversion of lithium polysulfides. The graded pore structure offers a high sulfur loading capacity of 64 wt % in the electrode, along with fast ion transport channels. Based on these characteristics, the NiS/S composite positive electrode achieved an initial discharge capacity of 1520 mA h/g at a high rate of 2 C. Still, it maintained a capacity of 720 mA h/g after 300 cycles (a capacity retention rate of 47.4%), with a stable Coulombic efficiency of over 99.8%. Impedance spectroscopy revealed a unique interface activation phenomenon, with a 68% decrease in charge transfer resistance and a suppression of the polysulfide diffusion coefficient to the order of 10–14 cm2/s after cycling. These breakthroughs are attributed to the synergistic effect of “morphology genetics pore regulation interface optimization,” providing new material design ideas for practical lithium sulfur batteries with high energy density and long cycle life.