Size Effect and Interfacial Synergy Enhancement of 2D Ultrathin CoxZn1−x-MOF/rGO for Boosting Lithium–Sulfur Battery Performance

Abstract

Advanced cathode materials are developed to tackle the challenges of the polysulfide shuttle effect and slow sulfur redox kinetics in Li–S batteries. A particularly effective strategy is the creation of nanostructured sulfur-host, which boast high levels of conductivity and catalytic activity. Here, a series of ultrathin cobalt–zinc bimetallic MOFs with varying ratios are synthesized on rGO via a one-pot hydrothermal process. Furthermore, graphene's high specific surface area enhances electrical conductivity and structural integrity, thereby promoting the growth of 2D MOFs and synergistically optimizing sulfur contact and conversion kinetics. The Co_xZn_1-x-MOF/rGO has a disordered structure, resulting from the fine-tuned ratio of cobalt to zinc in the bimetallic centers, generates active sites and modulates the electronic properties, thereby enhancing LiPSs adsorption and catalysis serve as sulfur hosts. Among the composites, the Co_0.75Zn_0.25-MOF/rGO demonstrated exceptional LiPSs adsorption and catalytic activity, resulting in a high capacity of 649.69 mA h g⁻¹ after the 250th cycle with an E/S ratio of 12.56 µL mg⁻¹ at 0.2 C. This work deepens the insights into the controlled design of defective MOFs, modulating their structure-activity correlations, and is expected to facilitate the integration of ultrathin defective MOFs with carbonaceous composites, thereby advancing the development of Li–S batteries.