Sulfur Loading Research Articles

Enhanced performance of Lithium–Sulfur cells via novel nano-sized iron-plated sulfur composites

Lithium–sulfur cells are promising energy-storage systems because of their high energy density and the desirable electrochemical utilization rates of cost-effective sulfur cathodes. However, the commercialization of high-performance lithium–sulfur cells, which are characterized by a high discharge capacity and cyclic stability, necessitates simultaneous optimization of both the cell-fabrication parameters and cell-performance values. Here, we introduce a novel iron-plated sulfur composite featuring nano-sized conductive iron plating applied to micro-sized insulating sulfur particles through an innovative electroless-iron plating method. The iron-plated sulfur composite facilitates the realization of a lean-electrolyte lithium–sulfur cell at a low electrolyte-to-sulfur ratio of 5 μL mg−1, enabling high-loading sulfur cathodes (sulfur loadings of 10–14 mg cm−2) to attain a reversible discharge capacity (945–1033 mAh g−1) and a cycle life of 400 cycles. These well-controlled cell-fabrication parameters, coupled with the high cell performance, result in improved performance metrics, such as high areal capacity (10–13 mAh cm−2), improved energy density (22–28 mWh cm−2), and a low electrolyte-to-capacity ratio (4.8 μL mAh−1). These advancements are attributable to the incorporation of plated nano-sized iron, which endows the cathode with rapid electron/ion transfer, robust polysulfide retention, and heightened electrocatalysis capabilities for conversion-type battery chemistry.

An anthraquinone derivative for modulating the energy levels of polysulfide molecular orbitals to enhance the kinetics of redox reactions

The shuttle effect of lithium polysulfides (LiPSs) and the slow kinetics of sulfur redox reactions severely hinder the commercialization of lithium-sulfur (Li–S) batteries. In this study, 2,6-dihydroxyanthraquinone (DHAQ) is absorbed onto the surface of carbon materials through π-π interactions to facilitate the adsorption and catalytic conversion of LiPSs. Electrostatic potential (ESP) results indicate that introducing hydroxyl groups into the molecule enhances the carbonyl group's ability to adsorb LiPSs and thereby facilitates the formation of covalent Li-O bonds for their immobilization. The interaction between DHAQ and LiPSs results in a complex with a higher energy level for the highest occupied molecular orbital (HOMO) and a lower energy level for the lowest unoccupied molecular orbital (LUMO). This leads to enhanced redox activity, which accelerates the kinetics of LiPSs conversion reactions. Consequently, the S@DHAQ/C composite demonstrates a capacity decay rate of just 0.040 % per cycle after 600 cycles at 1 C. At a sulfur loading of 5 mg cm−2, it retains an initial discharge specific capacity of 643 mAh g−1 at 0.2 C. This work introduces a novel approach to improving polysulfide adsorption capacity through organic molecules while also accelerating the kinetics of redox reactions.

Preparation of MoS2 nanosheets/nitrogen-doped carbon nanotubes/MoS2 nanoparticles and their electrochemical energy storage properties

Inferior electrical conductivity, huge volume swell, shuttle effect and slow redox reactions in Li-S batteries restrict their practical applications. In this study, molybdenum disulfide nanosheets anchored on nitrogen-doped carbon nanotubes encapsulating molybdenum disulfide nanoparticles (MoS2/NC/MoS2 NTs) were prepared by heat treatment, ammonia etching, high-temperature sulfurization, and solvent-thermal in-situ growth using polypyrrole-coated molybdenum trioxide nanorods (MoO3 NRs) as templates. The hollow structure of nitrogen-doped carbon nanotubes and the high specific surface area are conducive to increasing sulfur loading, increasing the contact area of electrolyte, accelerating the electron transport, and shortening the lithium ion transport route. The MoS2 nanosheets on the outer layer of the nitrogen-doped carbon tubes and the MoS2 particles wrapped inside can anchor polysulfides by chemisorption, slowing down the shuttle effect and enhancing the energy storage performance of lithium-sulfur batteries. The MoS2/NC/MoS2/S nanotubes (MoS2/NC/MoS2/S NTs) maintain a capacity of 498.9 mAh g−1 over 500 cycles at 1.0 A g−1, with an average single-cycle capacity decay rate of 0.061 %. The density functional theory calculations, the adsorption experiments, and the X-ray photoelectron spectroscopy results all confirm that the MoS2/NC/MoS2 NTs are able to anchor lithium polysulfides through strong adsorption, thus effectively mitigating the shuttle effect of polysulfides. The synthesis of MoS2/NC/MoS2/S NTs in this study is of important significance for the development of advanced lithium-sulfur batteries.

P‐doped RuSe2 on Porous N‐doped Carbon Matrix as Catalysts for Accelerated Sulfur Redox Reactions

Monocomponent catalysts exhibit the limited catalytic conversion of polysulfides due to their intrinsic electronic structure, but their catalytic activity can be improved by introducing heteroatoms to regulate its electronic structure. However, the rational selection principles of doping elements remain unclear. Here, we are guided by theoretical calculations to select the suitable doping elements based on the balanced relationship between the adsorption strength of lithium polysulfides (LiPSs) and catalytic activity of lithium sulfide. We apply the screening method to develop a new catalyst of phosphorus doped RuSe2, manifesting the further enhanced conductivity compared with original RuSe2, facilitating charge transfer and further modulating the d–band center of RuSe2, thereby augmenting its effectiveness in interacting with LiPSs. Consequently, the assembled cell exhibits an areal capacity of 7.7 mAh cm–2, even under high sulfur loading of 8.0 mg cm–2 and a lean electrolyte condition (5.0 μL mg–1). This rational screening strategy offers a robust solution for the design of advanced catalysts in the field of lithium–sulfur batteries and potentially other domains as well.

Fabrication of sulfur-based functionalized activated carbon as solid phase extraction adsorbent for selective analysis of selenite in water

Based on the important feature of sulfur with excellent selectivity toward selenite in the presence of selenate, a simple and low-cost adsorbent of solid phase extraction known as sulfur loading activated carbon (SAC-6) was successfully prepared and applied for selenite (Se(IV)) analysis in water. Microstructure and morphological characteristics of SAC-6 had been identified by XRD, TEM, BET and FT-IR. In the static adsorption experiments, Se(IV) could be separated in a wide range of pH values (pH=3–11). The retention process of Se(IV) onto SAC-6 was characterized as spontaneous exothermic reaction. An obvious change of adsorption mechanism occurred in static and dynamic adsorption processes shown that the behaviors followed monolayer and hybrid adsorption. The theoretical maximum adsorption capacity of SAC-6 calculated by Langmuir-Freundlich was 13.48 mg/g. The microcolumn filled with SAC-6 was applied to extract Se(IV) in water solution. The detection limit of Se(IV) analytical procedure was confirmed as 0.27 μg/L within a linear range of 10–1000 μg/L. A good precision with relative standard deviation of 1.34 % (100 μg/L, n = 6) was achieved. The high adaptability and accuracy of SAC-6 microcolumn was validated by analyzing natural water samples and certified reference materials. Our work successfully excavated the application value of the sulfur selectivity, and also provided a new adsorbent for Se(IV) extraction and analysis.

P-doped RuSe2 on Porous N-Doped Carbon Matrix as Catalysts for Accelerated Sulfur Redox Reactions.

Monocomponent catalysts exhibit the limited catalytic conversion of polysulfides due to their intrinsic electronic structure, but their catalytic activity can be improved by introducing heteroatoms to regulate its electronic structure. However, the rational selection principles of doping elements remain unclear. Here, we are guided by theoretical calculations to select the suitable doping elements based on the balanced relationship between the adsorption strength of lithium polysulfides (LiPSs) and catalytic activity of lithium sulfide. We apply the screening method to develop a new catalyst of phosphorus doped RuSe2, manifesting the further enhanced conductivity compared with original RuSe2, facilitating charge transfer and further modulating the d-band center of RuSe2, thereby augmenting its effectiveness in interacting with LiPSs. Consequently, the assembled cell exhibits an areal capacity of 7.7 mAh cm-2, even under high sulfur loading of 8.0 mg cm-2 and a lean electrolyte condition (5.0 μL mg-1). This rational screening strategy offers a robust solution for the design of advanced catalysts in the field of lithium-sulfur batteries and potentially other domains as well.

Nano-sulfur decorated graphene oxide to improve the mechanical properties of natural rubber by interfacial participate in the vulcanization reaction

As a new material with excellent comprehensive properties, graphene is an excellent reinforcing agent for natural rubber (NR). However, how to improve the interface performance between graphene and NR, and at the same time be practical, is still a great challenge. In this study, nano-sulfur decorated graphene oxide materials (GO-S) were prepared by in-situ loading nano-sulfur on the surface of graphene oxide (GO). Nano-surface cross-link with NR in the vulcanization process, acts as a bridge to anchor GO and NR molecular chains and improve the interface bonding strength of GO and NR. The AFM results show that the interfacial phase thickness of NR-GO-S composites increased from 135 ± 18 nm to 245 ± 28 nm after in-situ loading modification. The tensile strength and tear property of NR-GO-S composites modified by sulfur loading reach 30.3 MPa and 40.0 kN⋅m−1, respectively, which are 31.1 % and 12.8 % higher than those of NR-GO composite. Nano-sulfur form O–S and C–S covalent bonds with GO, and form more efficient covalent crosslinking networks with NR molecules in the vulcanization process, thus improving the interfacial compatibility between GO and NR and making the load transfer in rubber matrix more effective. This work provides a new idea and method to improve the interface property between rubber and inorganic nanomaterials.

Dual-engineering of tungsten doping and carbon incorporation in vanadium carbide arrays to accelerate the polysulfide conversion for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are promising candidates for next-generation electrochemical energy storage systems by virtue of the high energy density, low-cost, and ecofriendliness. Unfortunately, the sluggish sulfur conversion kinetics, notorious shuttle effect of lithium polysulfides (LiPSs) and severe volumetric variation during the lithiation/delithiation process result in insufficient sulfur utilization and fast capacity degradation. Herein, tungsten-doped vanadium carbide nanosheet arrays strongly coupled with a thin nitrogen-doped carbon layer directly grown on carbon cloth substrate (denoted as CC/W-VC@NC) have been conceptually designed as an advanced sulfur host to resolve the aforementioned problems. Specifically, the binder-free CC/W-VC@NC sulfur host not only strongly interacts with LiPSs, but also presents superior electrocatalytic activity for rapid LiPSs conversion. Additionally, the arrayed architecture provides sufficient space for sulfur loading and simultaneously accommodates its volumetric variation. Furthermore, theoretical calculations elucidate that tungsten doping can regulate the electronic structure, improve the electrical conductivity and strengthen the chemisorption toward LiPSs. Attributing to the multifarious advantages, Li-S batteries assembled with CC/W-VC@NC/S cathode exhibit a high initial discharge capacity of 1305.9 mAh/g at 0.1 C, as well as superior rate capability (709.8 mAh/g at 5 C) and good long-term durability (capacity decay rate of only 0.063 % per cycle over 500 cycles at 1 C). This study presents an effective approach to construct transition metal carbides as high-performance sulfur hosts for Li-S batteries.

Enhanced Li bonds enable bidirectional sulfur catalysis by a molecular Co-N4 catalyst for lithium-sulfur batteries

Sulfur conversion catalysis is an effective strategy to tackle the inherent polysulfide shutting and fast capacity decay in lithium-sulfur batteries. Previous studies identified cobalt phthalocyanine as a unique molecular catalyst with Co-N4 active sites to promote sulfur reduction reactions. Herein, enhancing the Li bonds with the pyridinic N atoms on the phthalocyanine ligand is demonstrated to endow further catalytic activity in sulfur oxidation reactions. This is enabled by peripheral substitution with electron-donating methoxy groups that strengthens the electronegativity of the pyridinic N atoms. DFT calculations and metadynamics simulations identify the key role of Li bonds in reducing the energy barrier of Li2S dissociation. The highly lithiophilic methoxy groups also stabilize the dissociated Li cations in their solvation structure. The dissociated S anion can then be oxidized to higher-order polysulfides or radicals by electron donation to the Co-N4 center, which activates Li2S for subsequent oxidation. Meanwhile, the catalytic activity in sulfur reduction reactions is also improved by a more efficient electron transfer to adsorbed Li2S4, during which the strengthened Li bonds are beneficial in mediating the breakage of the bridging S-S bond. Significant performance improvements are achieved with the bidirectional catalyst under high areal sulfur loading and in Li-S pouch cells.

Atomically precise Ag30Pd4 nanocluster as efficient polysulfides redox catalyst in Li-S batteries

Regulating the catalyst electronic structure is critical for improving the adsorption and catalytic conversion of lithium polysulfides (LiPSs) in lithium-sulfur batteries (Li-S), yet which has been overlooked in current studies. In this work, structurally defined Ag30Pd4 nanoclusters were loaded onto reduced graphene oxide (Ag30Pd4/rGO) as a modification material for polypropylene (PP) separators to elucidate the catalytic activity towards lithium polysulfides and the impact on the electrochemical properties to lithium sulfur batteries. This unique d-π combination promotes charge transfer, influences overall charge states, and further enhances adsorption energies in potential reaction pathways with lithium polysulfides. Consequently, the Ag30Pd4/rGO/PP modified batteries exhibited an exceptionally low-capacity decay rate of 0.026% per cycle at 1.0C over 1000 stable cycles and 9.75 mAh cm−2 excellent performance even with lean electrolyte and high sulfur loading (9.7 mg cm−2). This study paves a path for employing ultrasmall bimetallic nanoclusters to promote the polysulfides redox kinetics hence boosting the lithium-sulfur battery performance.

In-situ analysis of cathode and anode impedances to probe the performance degradation of lithium–sulfur batteries

Improving the performance of Li-metal batteries with sulfur cathodes while maintaining high sulfur loading (>4 mg cm−2) and low electrolyte-to-sulfur ratio (<10 mg μL−1) is a significant challenge. These conditions often result in poor battery cycle life and sudden capacity failure during charge-discharge processes. To address this challenge, we investigate Li–S batteries in a three-electrode (3E) configuration, utilizing optimized materials and geometries for the reference electrode. This configuration allows us to independently track the in-situ variations in cathode and anode resistances, along with the electrode potential difference, unveiling the root causes of abrupt battery failure during cycling. Our 3E approach uncovers previously unnoticed distortion phenomena in the electrochemical impedance spectra of both the cathode and anode, providing essential indicators of imminent micro-short circuiting. Supported by simulations using the finite element method and equivalent circuit analysis software, these insights clarify that the primary reason for battery failure is the growth of Li dendrites and their subsequent contact with the cathode, rather than a sudden increase in cell impedance. By substituting traditional Li foil with a specially designed Li anode less susceptible to Li dendrite growth, we achieve reduced anode resistance and improved battery capacity and cycle life stability. This research reveals the potential of the 3E configuration for precise in-situ impedance monitoring, which is valuable for devising strategies to enhance cycle stability.

DMSO/DMF co-solvent precipitated nano-sulfur cathode for highly loading lithium-sulfur pouch cells

We employ a simple anti-solvent precipitation method to prepare sulfur nanoparticles. Dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) are chosen as co-solvents, and cetyltrimethylammonium bromide (CTAB) is used as a stabilizer. By adjusting parameters such as the ratio of solvents and concentration, we precisely control the supersaturation, finely tuning the size of the sulfur particles. To enhance the electrical conductivity of the electrode materials, we uniformly composite sulfur with reduced graphene oxide (rGO). As the sulfur particle size decreases, the charge transfer resistance of the S@rGO cathode rapidly decreases, demonstrating excellent electrode kinetics. A lithium-sulfur coin cell assembled with S@rGO-75 exhibits a discharge specific capacity of 1272 mAh g−1. After 180 cycles, the capacity retention remains at 89.1 %, with a Coulombic efficiency of 98.9 %. Additionally, a pouch cell (PC-75) achieves stable charge–discharge behavior at a total sulfur loading of 300 mg, with an initial discharge specific capacity of 1047 mAh g−1 and a capacity retention of 63.7 % after 80 cycles. Under lean electrolyte conditions (E/S = 1.5 μl mg−1), PC-75 maintains outstanding energy density (392.3 Wh kg−1). Based on PC-75, a drone achieves an ultra-long flight time of 255 s, providing preliminary evidence of the practical application potential of PC-75.

Facilitating sulfur species capture and bi-directional redox in Li-S batteries with single-atomic Co-O2N2 coordination structure

Lithium-sulfur (Li-S) batteries suffer from the shuttle effect of soluble lithium polysulfides (LiPSs) and slow redox kinetics, significantly limiting their practical application. Although single-atom catalysts (SACs) offer a promising strategy to address these challenges, designing materials with optimal adsorption force and high catalytic activity remains a grand challenge. Here, we present a cobalt (Co)-based SAC with unique Co-O2N2 coordination structures for Li-S batteries. Both experimental and theoretical studies demonstrate that O, N-coordinated Co single atoms anchored on a porous carbon framework (Co/NOC) effectively capture LiPSs and dramatically catalyze bidirectional polysulfide conversion. The expanded carbon layer spacing facilitates lithium ions diffusion and maximizes the exposure of active sites. As a result, Li-S batteries incorporating Co/NOC as separators exhibit outstanding rate performance (906.6 mAh g−1 at 3 C) and exceptional cycling stability, even at −10 °C. Furthermore, with a high sulfur loading of 12.0 mg cm−2, the areal specific capacity reaches up to 12.36 mAh cm−2. This work provides some useful insights for the design of high-performance SACs for Li-S batteries.

(Invited) Stabilizing the Electrodes and Interfaces in Lithium-Sulfur Batteries

As the electrification of transportation sector and grid storage of electricity produced from renewable sources like solar and wind are rapidly evolving, cost, sustainability, and supply chain challenges will become the dominant issue. Lithium-sulfur batteries offer significant sustainability and cost advantages compared to the currently used lithium-ion batteries as sulfur is abundant and inexpensive and offers an order of magnitude higher capacity than the oxide cathodes. However, the commercialization of lithium-sulfur batteries is met with a few challenges, such as poor cycle life in practical cells. These challenges originate from the poor electronic and ionic conduction in sulfur and its discharged products, polysulfide shuttle, and poor cyclability of lithium-metal anode. To overcome some of these difficulties, generally a large amount of conductive carbon and liquid electrolyte are added to the cell; they enhance the cycle life, but drastically lower the practical energy density and make the lithium-sulfur batteries uncompetitive with lithium-ion batteries. To overcome the above challenges, this presentation will focus on optimizing sulfur and lithium sulfide cathodes, incorporation of electrocatalysts into the cathode to enhance sulfur redox, development of advanced electrolytes, incorporation of additives into the cathode and electrolyte to stabilize the cathode-electrolyte and anode-electrolyte interfaces, anode-free cells that eliminate the handling of thin lithium-metal foils, while keeping the sulfur loading and electrolyte/sulfur ratio at a practically accepted level. The improvements achieved and the mechanisms involved in the performance improvement will be discussed based on in-depth characterization data obtained with time-of-flight secondary ion spectrometry (TOF-SIMS), x-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR) spectroscopy, etc.

High-Density, Low-Tortuosity Sulfur Electrodes for High Energy Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries have attracted significant attention due to their promising theoretical energy and cost-effectiveness.[1] While recently studies have predominantly focused on increasing sulfur mass loading and utilization rate for high specific energy, there remains a noticeable gap in addressing the intrinsic challenge of improving volumetric energy density.[2] This challenge arises as many Li-S investigations rely on highly porous electrodes.[3] Here, we employ a shear-rolling approach to prepare free-standing electrodes characterized by high density (porosity<15%), low tortuosity, and substantial S content (>70%). The incorporation of a vascular-like porous network, facilitated by a pore soft template, plays a pivotal role in achieving high sulfur utilization (>1000 mAh g-1) in high-loading electrodes (>4 mg cm-2) under lean electrolyte condition (E/S 4 mL g-1). This approach results in an extraordinarily high volumetric energy density (668 Wh L-1 of dry cell) when applied to practical Li–S pouch cells. Our study underscores that realizing high volumetric energy in Li–S cell can be achieved by rationalizing the dense electrode architecture. Furthermore, the shear-rolling approach holds broad applicability for fabricating high-energy electrodes using porous or nanoparticle materials with desirable structures. Details of the progress will be discussed at the conference.

Suppressing Shuttle Effect in Lithium-Sulfur Batteries Using Perovksite Lead Zirconate Titanante Nanofibers

Rapid capacity fade and untimely failure caused by the infamous “shuttle effect” prevents the commercialization of Lithium-sulfur batteries (LSB). In this work, Lead Zirconate Titanate (PZT) nanofibers have been employed as polysulfide immobilizer in LSB. Ferroelectric materials possess a unique domain structure where each individual domain carries a dipole moment. The dipole-dipole interaction between the domains of the ferroelectric PZT nanofibers and polysulfides inhibits the diffusion of polysulfides from the cathode. In addition to electrostatic interactions, the 1-dimensional nanofibers with large specific surface area are accompanied by lithiophilic and sulfiphilic heteroatoms which act as anchoring points for chemically binding the polysulfides. Moreover, the enhanced wettability of the electrode arising from the favorable affinity of PZT nanofibers towards the electrolyte along with lithiophilic heteroatoms aids the diffusion of Lithium-ions. This enhanced wettability and the presence of lithiophilic surface promotes the diffusion of lithium ions which boosts the reaction kinetics. Briefly, the synergy of physical and chemical interaction of PZT nanofibers towards the polysulfide species is found to mitigate the shuttle effect and improve electrochemical performance of LSB. Further, a promising long-term cycling over 200 cycles for LSB cell with PZT interlayer is observed with 98 % Coulombic efficiency and slow fade rate of 0.08 % per cycle. Moreover, cells with higher sulfur loading and lower electrolyte to sulfur ratio reveal superior electrochemical performance with 80.8 % capacity retention over 100 cycles. Figure 1

Li-Ion Intercalating Cathode for Advanced Lithium-Sulfur Batteries

The advancement of lithium-sulfur (Li-S) batteries represents a significant shift in high-energy-density electrochemical storage, offering energy densities far exceeding those of traditional lithium-ion systems. This research contributes to the evolving field of Li-S batteries by proposing a novel strategy to optimize cathode performance, crucial in harnessing their full potential.Li-S batteries are characterized by their unique electrochemical process, which involves converting elemental sulfur to lithium sulfide (Li2S) during discharge via lithium polysulfide intermediates. A traditional challenge in this process is the notorious shuttle effect caused by lithium polysulfide intermediates. These intermediates, highly soluble in standard electrolytes, migrate continuously between the cathode and anode, leading to substantial active material loss, rapid capacity degradation, and reduced coulombic efficiency. Significant advancements have been made by introducing metal compounds with a chemical affinity for lithium polysulfides. However, a persistent challenge remains: the insulating nature of Li2S, which hinders electron transport. Recent strategies aiming to address these issues have focused on electrolytes with enhanced Li2S solubility to promote three-dimensional (3D) Li2S growth and prevent cathode passivation. Yet, the increased reactivity of such electrolytes poses new challenges, highlighting the need for alternative solutions.Our study explores this challenge, utilizing lithiated metal oxides as intercalating cathode materials to control Li2S growth dynamics. This method offers immediate mitigation of side reactions in the implementation of enhanced electrolytes. The scope of our research encompasses the thorough synthesis and characterization of these intercalating oxides, emphasizing their role in control Li2S growth. Additionally, we delve into the electrochemical characterization of these materials, focusing on their lithiation/delithiation kinetics and the consequent impact on Li-S battery performance. These intercalating oxides, capable of incorporating lithium ions within their crystal structure, present a promising path for aligning lithiation with Li2S formation, thereby fostering effective 3D growth. This contrasts with other oxides where asynchronous lithiation results in conventional two-dimensional (2D) Li2S growth, leading to premature discharge termination and suboptimal battery performance.We introduce a mechanism where 3D Li2S growth is driven by enhanced solvation of Li2S, intricately linked to the lithiation behavior of these oxides. By incorporating these optimized intercalating oxides in Li-S cells, we observe notable improvements in discharge capacity and sulfur utilization. This improvement is especially significant under high sulfur loading conditions, which typically exacerbate the polysulfide shuttle effect and pose formidable challenges for Li-S battery efficiency. Our investigation includes a detailed morphological analysis of Li2S deposition on various cathode surfaces. Employing advanced techniques like ex-situ Scanning Electron Microscopy (SEM) and electrodeposition modeling, we discern distinct Li2S growth patterns. These findings reveal that cathodes incorporating specific intercalating oxides exhibit reduced surface passivation due to predominant 3D Li2S growth, as opposed to the 2D growth observed in other oxide substrates. This variation in growth morphology significantly impacts cell performance, particularly under high sulfur loading conditions, where effective management of Li2S formation and polysulfide shuttling is crucial.In conclusion, this research marks a significant step in addressing the fundamental challenges of Li-S batteries. By leveraging the distinct properties of select intercalating oxides, the study not only deepens our understanding of Li2S growth mechanisms but also demonstrates an effective method to enhance Li-S battery performance. This work lays a foundation for future developments in high-energy-density battery technologies and signifies a crucial advancement towards the realization of more efficient and robust Li-S batteries.

Effective Lithium Polysulfides Anchoring on Vanadium Disulfide Facets for Lithium-Sulfur Batteries – A Computational Study

The commercialization of Li-S batteries is hindered by the shuttle effects of lithium polysulfides (LiPS) and the sluggish reaction kinetics. Hence, effectively trapping and promoting the conversion rates of LiPSs is of prime importance1. However, the fundamental kinetics of the electrocatalytic charging and discharging of Li-S batteries and the underlying mechanism have not been sufficiently explored yet.2 Therefore, by taking the 2D transition metal sulfide, VS2 as a model, we conducted a systematic investigation using density functional theory to study the ability of dominant exposed crystal planes of VS2 to trap LiPSs from leaching into electrolyte solvents and to act as an electrocatalyst to increase the Sulfur Reduction Reaction (SRR) kinetics3. To reflect a realistic environment of a battery, the effect of electrolyte solvents on the electrocatalytic activity was further investigated. Our calculations show that VS2 has moderate binding energy toward LiPSs which inhibits LiPS from leaching into electrolytes while fulfilling the key prerequisite to act as an electrocatalyst simultaneously.4 At the discharge, the conversion of S8 to the long chain Li2S8 was facile with a lower energy barrier while the rest of the reactions were sluggish explaining the accumulation of LiPSs. Further, the VS2 (001) facet exhibits excellent electrocatalytic activity for the SRR and Li2S decomposition reaction at charging compared to other dominant crystal planes, which significantly lowers the energy barriers of LiPS conversion during the charging and discharging process, ensuring high-rate performance and longer cycle life4. References Manthiram, A., Fu, Y., Chung, S.-H., Zu, C., & Su, Y.-S. (2014). Rechargeable Lithium–Sulfur Batteries. Chemical Reviews, 114(23), 11751–11787.Abraham, A. M., Thiel, K., Shakouri, M., Xiao, Q., Paterson, A., Schwenzel, J., Ponnurangam, S., & Thangadurai, V. (2022). Ultrahigh Sulfur Loading Tolerant Cathode Architecture with Extended Cycle Life for High Energy Density Lithium–Sulfur Batteries. Advanced Energy Materials, 2201494.Abraham, A. M., Boteju, T., Ponnurangam, S., & Thangadurai, V. (2022). A global design principle for polysulfide electrocatalysis in lithium–sulfur batteries—A computational perspective. Battery Energy, 20220003.Boteju, T., Abraham, A. M., Ponnurangam, S., & Thangadurai, V. (2023). Theoretical Study on the Role of Solvents in Lithium Polysulfide Anchoring on Vanadium Disulfide Facets for Lithium–Sulfur Batteries. The Journal of Physical Chemistry C.

The Impact of Biomass-Derived Graphene-like Porous Carbon Decorated with NiO Nanoparticles on the Electrochemical Performance of Lithium-Sulfur Batteries

Lithium-sulfur batteries are considered a promising next-generation energy storage system, boasting high theoretical capacity and energy density, approximately double that of LiBs [1,2]. However, challenges such as low sulfur conductivity, significant volume expansion during cycling, and the lithium polysulfides shuttle effect hinder their practical use [3]. These issues result in side reactions, irreversible loss of active material, and anode degradation, leading to a rapid decline in cell capacity stability [4].In this research, we successfully developed a sulfur cathode carbon matrix and separator modifier from rice husk through carbonization and thermal activation. The resulting graphene-like porous carbon (GPC) exhibited high efficiency as a sulfur host, enhancing the electrochemical performance of the cathode. The GPC-NiO composite also served effectively as a separator modifier, catalyzing lithium polysulfides' redox reactions and improving the overall cycling stability of lithium-sulfur batteries. In particular, the GPC@S/GPC-NiO-20 cell demonstrated an excellent initial discharge capacity of 1519 mAh g-1 at 0.2 C. Also, it delivered excellent long-term cycling, maintaining a discharge capacity of 661 mAh g-1 even after 400 cycles at 1 C, with a Coulombic efficiency exceeding 97%. It exhibited a promising rate capability of 568 mAh g-1 at 2 C and retained a discharge capacity of 603 mAh g-1 over 100 cycles at 0.2 C with a sulfur loading of 4.0 mg cm-2. Acknowledgments This research is funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP19677708).

High-Performance Lithium-Sulfur Batteries with Atomic V- and Co-Modified Ketjen Black-Sulfur Composite Cathode

Lithium-sulfur (Li-S) batteries are potential alternatives to lithium-ion batteries, which are known to have certain drawbacks. This has drawn special technological attention. Sulfur’s low electrical conductivity, shuttling of the intermediate polysulfides, the slow conversion reaction kinetics of various lithium polysulfides (LiPS), and the major volume change of sulfur in the lithiation reaction are some of the main issues that still need to be resolved before Li-S batteries can be used in practical applications. Additionally, it is likely because there are not enough prognostic models determining energy densities at the cell and pack level based on materials and cell design, most of the articles do not report system-level metrics, specific energy (Wh kg-1), and energy density (Wh L-1).To overcome these problems, atomic vanadium (V) and cobalt (Co) modified ketjen black-sulfur composite (VCKBS) was prepared and used as a cathode in Li-S batteries. The synthesized composite was characterized by various techniques, e.g., XRD, Raman, SEM, HR-TEM, HAADF-STEM, and XPS spectra. The polysulfide adsorption test showed that V had increased the adsorption ability, and cyclic voltammetry displayed the increased catalytic activity resulting from Co, offering a large number of interfacial active sites and ensuring smooth electron transfer. Cycling performance tests showed an initial specific capacity of 1329 mAh g−1, maintained at 1249 mAh g−1 after 100 cycles. Under a higher sulfur loading (2.4 mg cm−2), at 0.2 C, Li-S cells demonstrated an initial specific capacity of 1201 mAh g−1 and retained 985 mAh g−1 after 300 cycles with a low fading rate of 0.059% per cycle. The rate performance tests showed that the prior capacity is nearly recovered, going from 1C back to 0.1C, demonstrating the superiority of the VCKBS material.In addition to the experimental characterization of the Li-S cell performance, energy densities were also predicted by a proposed system-level performance model. The 1st and 100th discharge capacities were used to forecast the system-level specific energies and energy densities. The system-level specific energies and energy densities based on the 100th discharge capacity of VCKBS cathodes had improvements of 1342 and 568%, respectively. This suggests that an easy route to construct the highly stable cathode material may pave the way for the development of highly efficient Li-S batteries. Acknowledgments Hira Fazal acknowledges support from the Türkiye Scholarship/Research Fellowship Program sponsored by the Prime Ministry of Turkey Presidency for Turks Abroad and Related Communities (21PK070917). Damla Eroglu acknowledges support from the Istanbul Development Agency (Award No: TR10/21/YEP/0001). We also thank the National Natural Science Foundation of China (22171180) and the Science and Technology Commission of Shanghai Municipality (20520710400).