María Victoria Bracamonte

Lithium-sulfur (Li-S) batteries are promising next-generation energy storage systems due to their high theoretical energy density. However, their practical implementation is hindered by the low conductivity of sulfur and the polysulfide shuttle effect. In this work, garlic-braid-derived biochar was investigated as a sustainable sulfur host for Li-S battery cathodes. Biochar obtained from garlic braid biomass was chemically activated using potassium hydroxide to generate a highly porous carbon matrix. Sulfur was subsequently infiltrated into the activated biochar, and the resulting composite was evaluated as a cathode material in Li-S batteries. The activated biochar exhibited a well-developed porous structure, enabling a sulfur infiltration degree of 48 wt.%. The optimized cathode delivered an initial discharge capacity of 1,015 mAh/g and stabilized at approximately 700 mAh/g after 80 cycles at 0.1 C. Furthermore, a specific capacity of 491 mAh/g was achieved at 1 C, demonstrating favorable rate capability. The cells also exhibited stable Coulombic efficiency and good capacity retention during prolonged cycling. The enhanced electrochemical performance is attributed to the hierarchical porous structure generated by chemical activation, which promotes sulfur confinement, facilitates ion transport, and improves sulfur utilization. These findings demonstrate that garlic-braid-derived activated biochar is a promising and sustainable sulfur host for Li-S batteries, highlighting the importance of both biomass selection and pore structure engineering in the development of high-performance biochar-based cathodes.

Carbon‐based anodes remain central to lithium‐ion battery development, yet the relationship between oxidation state, structural disorder, and lithium‐ion transport kinetics is still incompletely understood. Here, we systematically compare commercial graphite (GPH), graphene oxide (GO), and exfoliated graphene (EGPN) as anode materials, combining morphological (scanning electron microscopy [SEM]), structural (X‐ray diffraction [XRD]), and chemical (X‐ray photoelectron spectroscopy [XPS]) characterization with an evaluation of electrochemical performance. Our results reveal that oxidation degree governs a fundamental trade‐off: insufficient oxidation, as in GPH, limits interlayer spacing and constrains Li ⁺ transport, while excessive oxidation, as in GO, introduces sp ³ ‐rich domains and oxygen‐containing functional groups that impede both electronic conductivity and ionic mobility. EGPN occupies a productive middle ground; its moderate surface functionalization and expanded interlayer spacing collectively enhance solid‐state and interfacial Li ⁺ diffusivity by up to two orders of magnitude relative to GO, enabling a specific capacity of 165 mAh g ⁻¹ at 1C with lower polarization losses. These findings demonstrate that electrochemical performance in carbon anodes is not simply a function of surface area or defect density, but of achieving an optimal balance between sp ² conductivity and controlled functionalization, a design principle with direct implications for next‐generation, high‐rate carbon anode materials.

Lithium-sulfur (Li-S) batteries are considered promising candidates for next-generation energy storage due to their high theoretical energy density and the abundance of sulfur. However, challenges such as poor compatibility with carbonate-based electrolytes and the need for excessive electrolyte volumes limit their practical implementation. Here, we explore biocarbon derived from olive pomace, an agricultural by-product, as a sulfur host for Li-S batteries operating in carbonate-based electrolytes. We use two KOH activation methods—liquid and solid—to tailor the porosity and surface properties of the biocarbon. The solid-activated biocarbon exhibits higher surface area, micropore volume, and sp ² carbon content, promoting efficient sulfur confinement and enabling solid-state sulfur conversion. We find that electrochemical performance remains stable regardless of sulfur loading or electrolyte volume. The resulting sulfur cathodes showed excellent electrochemical performance with a discharge capacity of 850 mAh g_S ⁻¹ with a sulfur loading of 4 mg_S cm⁻² and an electrolyte-to-sulfur ratio of 5 µL mg_S ⁻¹. Remarkably, these electrodes also perform well at high current densities, delivering a capacity of 620 mAh g_S ⁻¹ at 1 C and 360 mAh g_S ⁻¹ at 5 C.

The efficient and sustainable removal of organic dyes from wastewater remains a critical environmental challenge. In this study, cow hair, an abundant and underutilized agricultural waste, is transformed into biochar through a simple pyrolysis process to develop an effective and eco-friendly adsorbent for methylene blue (MB) dye removal. The physicochemical properties of the cow-hair biochar, including its surface area, porosity, and functional groups, were systematically analyzed to understand its adsorption performance. Batch adsorption experiments were conducted under varying conditions of pH, initial dye concentration, contact time, and pH to evaluate the adsorption efficiency of cow hair biochar. The results revealed that the biochar exhibits superior adsorption capacity for MB, driven by a combination of electrostatic interactions, π-π stacking, and surface oxygen functional group interactions. Using R2 as criteria, the best-fitting model was the Temkin isotherm, indicating a monolayer adsorption process with a maximum adsorption capacity surpassing many conventional adsorbents, achieving high levels of MB adsorption capacity of 730 mg/g. This study highlights the potential of converting cow hair waste into a high-performance adsorbent, offering a cost-effective and sustainable solution for dye-contaminated wastewater treatment. The findings pave the way for innovative waste valorization strategies and contribute to the advancement of green environmental technologies.

A variety of electrolyte additives were comprehensively evaluated to understand their relative capability in stabilizing lithium metal anode. Although the Li||Cu test is an effective test to rule out ineffective additives, a reliable assessment of individual additives cannot be obtained just by a single evaluation method. Therefore, various methods must be combined to truly assess the stabilization of a lithium anode. Moreover, it was also discovered that a significant depletion of electrolytes occurred during the end-of-life of the lithium batteries, which partially contributed to the sudden failure of the lithium batteries during cycling. However, the main culprit of the sudden failure was identified as the significant increase in the resistance of the lithium metal anode. When used as an additive, cyclic fluorinated carbonates are the most effective in stabilizing the lithium anode and improving the cycling performance of lithium batteries among all the common additives. Despite its cost-effectiveness, the additive in the conventional electrolyte approach provides insufficient protection for lithium metal due to the complete consumption of the additive materials, which is necessary to repair the solid-electrolyte interphase (SEI). Therefore, it is suggested that a larger ratio (>15 wt %) of the SEI former should be employed to achieve effective lithium stabilization.

A sustainable cow hair‐based biocarbon/sulfur composite was prepared via a melt‐diffusion process and used as cathode for lithium–sulfur (Li−S) batteries, exhibiting high capacity, good rate capability, and excellent cyclability. The effect of the activation process during the formation of the biocarbon was deeply analyzed by thermogravimetry, N ₂ adsorption, X‐ray photoelectron spectroscopy, scanning and transmission electron microcopy, among others. A correlation between the composition and the surface area with the electrochemical performance was found. The best results were obtained using an activated sample and composite electrode containing 73 wt % sulfur, which present an initial discharge capacity of around 1200 mAh/g and 799 mAh/g after 100 cycles at a current density of 0.1 A/g. Moreover, a specific capacity of ~701 mAh/g was measured at 1 C. The great electrochemical performance of this electrode in Li−S batteries is attributed to the porous carbon structure. Taking into account that hair is one of the major waste produced in the leather sector, this work presents a promising approach to reuse this material by giving it added value through the preparation of carbon/sulfur composites for high‐performance Li−S batteries.