Porous carbon derived from agave bagasse modified with iron as cathodes for lithium-sulfur batteries

Designing high capacity, stable lithium-sulfur cells is a critical global research focus. While waste-derived porous carbons show potential for improving Li–S cell performance, their surface requires modification to enhance lithium polysulfide uptake. Iron compounds are particularly attractive as active sites due to their abundance and low-cost synthesis. This study explores the synergistic benefits of iron doping and the surface/porosity of porous carbon obtained from agave bagasse, a common residue from tequila production. The impact of functionalization on carbon properties and electrochemical performance was evaluated. The materials were characterized using ASAP, XRD, RAMAN, SEM-TEM, TGA, and PZC, and their properties were directly correlated with the electrochemical behavior of the cell. Notably, a 4 % incorporation of iron carbide combined with a rich distribution of pore structure and a high graphitization yielded an initial discharge capacity of 1529 mAh g −1 at 1C. The material with 4 % of iron showed better performance compared to the material with higher iron content (7 %) and unmodified carbon. The adsorption experiments showed high performance for the material with 4 % iron content, reaching a polysulfide uptake of 0.72 mL/mg. This result highlights the importance of achieving a proper balance between porosity and active sites. These findings demonstrate that valorizing waste from the tequila industry into iron-functionalized carbons offers a cost-effective and sustainable route to enhance Li–S battery performance, contributing to the development of advanced energy storage technologies. • Agave bagasse was converted into porous carbon for Li–S cathodes, yielding 41% carbon with hierarchical micro/mesoporosity. • Iron nanoparticles (∼37.5 nm) were incorporated via thermal decomposition. • Enhanced Lithium polysulfides adsorption was evidenced by UV–vis on synthetized porous carbons. • Iron presence improved the initial capacity (1529 mAh g −1 ) of the Li–S at multiples C-rates. • A balance between iron content and porosity must be maintained in the materials.