Carbon Pore Architecture for Sulfur Accommodation, Retention, and Electrochemical Kinetics in Lithium–Sulfur Cells

Abstract

Lithium–sulfur cells provide an ideal platform for studying how carbon pore architecture governs sulfur accommodation, polysulfide retention, and electrochemical kinetics. Although porous carbons with different pore characteristics have been investigated, their intrinsic pore-structure effects remain difficult to distinguish because previous studies generally employ independently synthesized carbons with different surface chemistries and morphologies. Here, we establish an experimental platform by systematically blending commercial porous carbons with controlled pore architectures while preserving their intrinsic physicochemical properties. Dynamic image analysis, gas adsorption, electron microscopy, elemental mapping, and thermogravimetric analysis reveal systematic changes in pore structure, particle morphology, sulfur distribution, and sulfur retention as the carbon ratio is varied. Sulfur confined within micropore-dominated structures exhibits greater thermal stability than sulfur accommodated in mesopore-dominated structures, demonstrating that sulfur accommodation and sulfur retention are fundamentally different processes. Electrochemical measurements further establish a clear structure–property relationship, showing that micropore-dominated architectures enhance sulfur retention but impede ion transport, whereas mesopore-dominated architectures facilitate reaction kinetics at the expense of sulfur confinement and electrode stability. An optimized pore architecture balances these competing effects, enabling efficient sulfur utilization, suppressed polysulfide migration, improved reaction kinetics, and stable cycling under high sulfur loading. As a result, this study provides mechanistic insight and practical design principles for rational pore-architecture engineering in lithium–sulfur cells.