Beyond point defects: a first-principles investigation of topological line defects in graphene as continuous catalytic highways for Li-S batteries

Lithium-sulfur (Li-S) batteries have long been plagued by the shuttle effect and sluggish sulfur conversion, which limit their practical application. To address these issues, we propose and investigate several line-defect graphene configurations (including d5d7G, t5t7G, and 585G) as sulfur cathode host materials in Li-S batteries and evaluate their adsorption and catalytic potential using first-principles calculations. The results demonstrate that the continuous high-density linear defects are rich in active sites, which not only enhance the adsorption and the catalytic activity for lithium polysulfides (LiPSs), but also maintain a low barrier for Li⁺ diffusion. A qualitative correlation between the p-band center and the Gibbs free energy barrier is established, directly linking the defect topology to the catalytic activity. Comprehensive screening identifies the 585G configuration as the most promising candidate, as it exhibits the strongest polysulfide adsorption (E_a = -0.90 to -1.86 eV), the highest p-band center (-1.10 eV), and the lowest Gibbs free energy barrier (2.35 eV). This work provides insights into how the line-defect architectures govern the catalytic activity in graphene, offering a new design paradigm for the carbon-based sulfur hosts.