Lithium-sulfur batteries are recognized as potential next-generation energy storage devices due to their superior energy density and affordability. However, the dissolution of lithium polysulfides (LiPS) in the electrolyte induces a shuttle phenomenon, depleting active materials and shortening battery lifespan. This study examines the use of Co single-atom (CoSA) catalysts supported on an N-doped carbon matrix to mitigate the polysulfide shuttle effect. By varying the concentrations of Zn2+ and Co2+, the synthesis of ZnCo-Zeolitic imidazolate framework (ZIF) was optimized, enabling the uniform dispersion of Co single atoms within an N-doped carbon matrix. The Co2SA-CN@S electrode, derived from ZnCo-ZIF with an optimal Zn2+ to Co2+ concentration ratio of 8:2, achieved a specific capacity of 1113 mAh g–1 at 0.1 C and demonstrated excellent rate performance of 647 mAh g–1 at 1.0 C. This study confirms that the concentrations of Zn2+ and Co2+ during the synthesis of ZnCo-ZIF significantly influence Co particle aggregation and the formation of Co single atoms after heat treatment. The N-doped metal- organic framework-derived carbon, supported by single cobalt atoms, referred to as Co single-atom carbon nanomaterials (CoSA-CN), synthesized with optimal reactant concentrations, effectively enhances polysulfide conversion during redox reactions, minimizes LiPS migration, and suppresses the shuttle effect. This research reveals that controlling metal ion concentrations (Co2+ and Zn2+) is an effective strategy to limit an aggregation of metal catalysts, thereby producing single atoms more efficiently and ensuring their uniform distribution within the carbon matrix.