Synergistic effect of adsorption and electrocatalysis of CoO/NiO heterostructure nanosheet assembled nanocages for high-performance lithium-sulfur batteries

The dissolution and sluggish redox kinetics of lithium polysulfides (LiPSs) hinder the practical electrochemical performance of lithium-sulfur (Li-S) batteries. The modification of separators with functional materials plays an important role in improving the electrochemical performance of Li-S batteries. In this work, CoO/NiO heterostructure nanosheet assembled nanocages (CoO/NiO@C-NC) derived from NiCo-LDH with ZIF-67 as the template are synthesized to modify the separator of Li-S batteries. CoO/NiO@C-NC shows strong physical adsorption, chemical interaction, and even superior catalytic activity towards LiPSs due to its high surface area and CoO/NiO heterostructure, thus suppressing the dissolution and accelerating the solid-liquid-solid conversion kinetics of LiPSs. In particular, NiO can promote solid-liquid kinetics, and CoO is more favorable to accelerate the liquid-solid kinetics of LiPSs. With CoO/NiO@C-NC coated on the separator, the electrochemical performance of Li-S batteries is improved significantly due to the synergistic effect of adsorption and electrocatalysis of the CoO/NiO@C-NC. The modified Li-S battery shows a high discharge capacity of 738 mA h g −1 at 3C rate, a low capacity decay rate of 0.075% for 500 cycles at 1C, and an areal capacity of 5.8 mA h cm −2 with a high sulfur loading of 5.87 mg cm −2 . This work provides a novel method for the preparation of hollow heterostructure materials for high-performance Li-S batteries. CoO/NiO nanosheet assembled nanocages (CoO/NiO@C-NC) were prepared to improve the electrochemical performance of Li-S batteries. CoO/NiO@C-NC shows a synergistic adsorption-electrocatalysis effect to accelerate the redox of lithium polysulfides.