Solid Sulfur Research Articles

Allothermally Heated Reactors for Solar-Powered Implementation of Sulphur-Based Thermochemical Cycles

Catalytic sulphur trioxide splitting is the highest-temperature (650-950oC), endothermic step of several sulphur-based thermochemical cycles targeted to production of hydrogen or solid sulphur. Concentrated solar power tower plants are an attractive renewable energy source to provide the necessary heat. Furthermore, the development of solar receivers capable of delivering solid or gaseous heat transfer fluids at these temperature ranges enable the implementation of such endothermic reactions in allothermally-heated reactors/heat exchangers placed away from the solar receiver. In this context, a 2-kW laboratory-scale shelland-tube reactor/heat exchanger to perform thermal sulphuric acid decomposition and catalytic sulphur trioxide splitting was in-house designed, built and tested with electrically heated bauxite particles, in the perspective of eventually coupling such a reactor with a centrifugal particle solar receiver. Thermal test runs demonstrated the in-principle feasibility of the concept. The temperatures reached were sufficient to ensure complete sulphuric acid evaporation. However, the ones in the SO3 splitting zone were of the order of 750°C, high enough to demonstrate SO3 splitting but not reaching the levels required for close-toequilibrium conversion of the Fe2O3 catalyst system used (~ 850oC). An improved version of the reactor is under construction incorporating design modifications based on lessons learned from the test campaigns, in the perspective of scaling up the process.

Mechanism insight into the conversion between COS and thiophene during CO2 gasification of carbon-based fuels

Thiophene is the organic sulfur with good thermal stability in carbon-based fuel, clarifying the conversion mechanism between thiophene and COS is beneficial for achieving in-situ sulfur fixation during CO2 gasification of carbon-based fuels, but the mechanism has rarely been reported. Therefore, calculations based on density functional theory were performed and 16 reaction paths were proposed in this research, clarifying the decomposition mechanism of thiophene and re-fixation mechanism of COS. The attachment of CO2 will lead to the destruction of the thiophene ring and the generation of COS, and CO2 adsorption is the rate-determined step, while the carbon atom that adjacent sulfur atom is the reaction active site. However, the energy barriers of CO2 addition reactions are lower than those of CO2 adsorption reactions, and the energy barrier of reactions occurring on the aliphatics are lower than that occurring on the aromatics. The combination of CO2 and thiophene will thermodynamically lead to the generation of COS and CO. Moreover, gaseous sulfur generated from thiophene decomposition will be converted mutually, while H2S will not be converted into COS. Furthermore, COS will be captured by char, forming solid organic sulfur. The re-fixation of COS will occur on aliphatic chains from the decomposition of aromatics.

Sulfur release behavior and sulfur fixation mechanism during biomass microwave co-pyrolysis of Ascophyllum and rice straw

Co-pyrolysis with low-sulfur biomass is expected to improve the yield and quality of bio-fuels, without the usage of calcium-based desulfurizer. Sulfur transformation during microwave fluidized-bed co-pyrolysis between terrestrial and marine biomass (Ascophyllum, AS; Rice straw, RS) was investigated. Sulfur release was promoted during biomass co-pyrolysis, but it was inhibited during pyrolysis between AS and low-sulfur char. Thermal cracking of biomass was promoted during co-pyrolysis between biomass, accelerating the combination of H atoms and −SH radicals. Introduction of low-sulfur bio-char (CA) inhibited the generation of bio-char and the release of sulfur. Released sulfur was captured by –OH/C = C functional groups on bio-char through dehydration reactions/addition reactions, forming mercaptan in bio-char. Furthermore, introduction of microwave and bio-char promoted the cyclization and aromatization reaction, converting mercaptan to thiophene and improving the thermal stability of solid sulfur, and thus increasing in-situ sulfur fixation rate.

Deactivation of an Fe-based catalyst in the dehydrogenation of light alkanes under H2S co-feeding: A case study

The effectiveness of a Ru-Fe/SiO2 catalyst, which exhibits excellent propane dehydrogenation with H2S co-feeding, was verified for the dehydrogenation of various lower alkanes. When the dehydrogenation characteristics of C2–C4 alkanes were evaluated under H2S co-feeding, the Ru-Fe/SiO2 catalyst exhibited a high dehydrogenation activity in all cases. However, a significant degradation tendency of the catalyst was observed when lighter alkanes with smaller carbon numbers were used as the feedstock. The deposition of coke (carbon) and solid sulfur and the reduction of Fe species were identified as the main factors responsible for catalyst degradation. To further evaluate the factors affecting catalyst degradation, the effect of co-feeding H2 with the gas feedstock on the catalyst performance was investigated. The reaction stability improved significantly with the co-feeding of H2 during ethane and propane dehydrogenation reactions. This outcome is attributed to the smooth reduction and removal of the carbon accumulated on the catalyst surface, which is the main cause of catalyst degradation.

The role of nanoporous carbon materials for thiophosphate-based all solid state lithium sulfur battery performance

Due to their high theoretical energy density, all solid state lithium sulfur batteries (LS-SSB) represent one of the most promising candidates for next-generation energy storage systems. Whilst high sulfur utilizations have been published for several cathode compositions and preparation methods in recent years, there is still a lack of clarity regarding the influence of the used carbon. Furthermore, LS-SSBs face challenges in up-scaling as the common preparation methods including high energy ball milling are time consuming, batch-wise and need high energy impact. In this study, high sulfur utilization >1600 mAh gS−1 and reversibility with 80 % of initial discharge capacity after 60 cycles is achieved, using a more time-efficient preparation method with drastically lowered energy impact by selecting a suitable carbon. Additionally, the influence of the carbon nanostructure on the electrochemical performance is discussed. This study provides guidance in selecting nanostructured carbon materials to enable cost-efficient, up-scalable preparation methods for LS-SSBs without compromising on the excellent electrochemical performance.

Boron dopant- and nitrogen defect-decorated C3N5 porous nanostructure as an efficient sulfur host for lithium–sulfur batteries

Active site implantation and morphology manipulation are efficient protocols for boosting the electrochemical performance of carbon nitrides. As a promising sulfur host for lithium–sulfur batteries (LSBs), in this study, C3N5 porous nanostructure incorporated with both boron (B) atoms and nitrogen (N) defects was constructed (denoted as ND–B–C3N5) using a two-step strategy, i.e., pyrolysis of the mixture of 3-amino-1,2, 4-triazole and boric acid to obtain B-doped C3N5 porous nanostructure and then KOH etching under hydrothermal condition to generate N defects. The doped B atoms in the C3N5 porous nanostructure are in the form of B–N bonds and grafted B–O bonds. N defects are primarily created at the CN–C positions of the triazine unit, leaving behind some N vacancies and cyano groups. Benefiting from the involvement of B dopants and N defects, the optimized ND–B–C3N5–12 sample exhibits ameliorative conductivity, mass transport, lithium polysulfides (LiPSs) adsorption ability, diffusion of Li+ ions, Li2S deposition capacity, sulfur redox polarization, and a reversible solid–solid sulfur redox process. Consequently, the ND–B–C3N5–12/S cathode delivers accelerated redox performance of polysulfides for LSBs, revealing capacities of 1091 ± 44 and 753 ± 20 mAh/g at 0.2C for the initial and 300th cycles, respectively. The ND–B–C3N5–12/S cathode is also endowed with desired sulfur redox activity and stability at 2C for 1000 cycles, holding an initial discharging capacity of 788 ± 24 mAh/g and a low decay rate of 0.05 % per cycle.

Pilot-scale testing on catalytic hydrolysis of carbonyl sulfur combined with absorption-oxidation of H2S for blast furnace gas purification

About 70 % of the flue gas in the iron-steel industry has achieved multi-pollutant ultra-low emissions in China until 2023, and then the blast furnace gas purification has become the control step and bottleneck. Our research group has designed and constructed the world's first blast furnace gas desulfurization pilot plant with the scale of 2000 Nm3/h in October 2021. The pilot plant is a two-step combined desulfurization device including catalytic hydrolysis of carbonyl sulfur (COS) and absorption-oxidation of H2S, continuously running for 120 days. In the hydrolysis system, one reason for catalyst deactivation has been verified from the sulfur deposition. HCN in blast furnace gas can be hydrolyzed on the hydrolysis catalyst to produce the nitrogen deposition, which is one of the reasons for catalyst deactivation and has never been found in previous studies. The deposition forms of S and N elements are determined, S element forms elemental sulfur and sulfate, while N element forms -NH2 and NH4+. In the absorption-oxidation system, the O2 loading and the residence time have been optimized to control the oxidation of HS− to produce elemental sulfur instead of by-product S2O32−. The balance and distribution of S and N elements have been calculated for the whole multi-phase system, approximately 84.4 % of the sulfur is converted to solid sulfur product, about 1.3 % of the sulfur and 19.2 % of N element are deposited on the hydrolysis catalyst. The pilot plant provides technical support for multi-pollutant control of blast furnace.

Preventing Unplanned Shutdown due to Injection Well Plugging with After Treatment Unit Integrated Membrane at Matindok CPP

Pertamina EP Pertamina EP Donggi Matindok Field realizes that sustainable development activities need to pay attention to environmental aspects, including efforts to reduce the load of water pollution. In the production process at Matindok Central Processing Plant (CPP), byproducts are produced in 2 forms: solid sulphur and wastewater from the Biological Sulphur Recovery Unit (BSRU). Sulphur solids carried in wastewater can cause blockages known as plugging in injection wells and disrupt the production process. This study aims to reduce the water pollutants by integrating a nanofiltration membrane in the Bleed Water Treatment (BWT) to reduce the Total Dissolved Solid (TDS) content in wastewater after being processed in the After Treatment Unit (ATU). The experimental results showed a significant decrease in TDS values after nanofiltration membrane integration, from ≥14,000 mg/L to <4,000 mg/L. This program succeeded in reducing water pollution in 2023 by 272.68 tons of TDS.

Lean-Electrolyte Lithium-Sulfur Cells with a Core-Shell Cathode Configuration with High Active-Material Loading and Energy Density

Introduction The growing demand for rechargeable batteries with increasingly high energy density and low-cost active material has inspired the research of low-cost cathodes with higher specific capacities than those based on intercalation lithium-ion cathodes. Among these novel energy storage technologies, the lithium-sulfur electrochemical cell is the most promising because of the high energy density, low cost, wide availability, and low environmental impact of the sulfur cathode. However, the high-capacity sulfur cathode forms insulating solid sulfur and lithium sulfide in the fully charged and discharged states. The resulting high cathode resistance limits electrochemical utilization and reversibility, and the resulting low redox kinetics leads to the poor rate performance of sulfur cathodes. Moreover, these solid-state active materials are converted to liquid-state polysulfides during intermediate charging and discharging. The liquid-state polysulfides readily dissolve in the lithium-sulfur battery electrolyte, resulting in irreversible polysulfide loss and poor discharge-charge efficiency of the cell. The inefficient and unstable cell electrochemistry of sulfur can be mitigated by designing appropriate configurations of cathode materials. However, the modification of cathode materials often encounters the inability to accommodate a sufficient amount of sulfur in the cathode under lean electrolyte conditions while maintaining electrochemical stability. Results and Discussion In this presentation, we present the design of a core-shell architecture for the entire cathode, which features a conductive carbon shell having a fabric-like tubular structure to accommodate an active material core and provide fast charge transfer to the active material. In addition to the novel cathode configuration, we present a summary of a number of active material cores, including a pure sulfur core and a pure lithium sulfide core as solid-state active material cores, and a polysulfide catholyte core as a liquid-state active material (Figure 1) [1-3]. With these three different core-shell cathodes, we will comprehensively report the material design with high electrochemical utilization and efficiency, and the designed cell configuration stabilizes the reversible lithium-sulfur electrochemistry. Most importantly, we propose the sulfur core to demonstrate the high-loading sulfur cathode with the highest sulfur loading and content, and the sulfide and polysulfide cores to demonstrate the lean-electrolyte cells with low electrolyte to active material ratios. Specifically, we design a series of lithium-sulfur battery cathodes with a unique cathode material and configuration. In terms of the cathode material, a high-loading sulfur cathode prepared with pure sulfur powder, a high-concentration polysulfide prepared as the catholyte, and a sulfide cathode prepared in an ether-based solvent are reported. The sulfur, polysulfide, and sulfide serve as a high-loading active materials. The conductive carbon shell encapsulates the active material during cycling and resting. The integrated design of the cathode material and configuration enables the core-shell cathodes to achieve high sulfur loadings ranging from of 4 to 30 mg cm−2 and high sulfur contents in the range of 60-70 wt%. The high-loading core-shell cathodes excellent electrochemical utilization of the large amount of active material, showing high peak charge-storage capacity of 600-800 mA∙h g−1 at C/10 rate, long cycle life of 100-200 cycles, and high rate performance of C/10-C/2 rates with long-term cyclability and high capacity retention of 70% after 200 cycles. Moreover, by using polysulfide and sulfide cores, we demonstrate a lean electrolyte cell with low electrolyte/sulfur ratios of 6-3 μL mg-1. Accordingly, the designed core-shell cathodes achieve a high areal capacity of about 10 mA∙h cm-2, high gravimetric capacities of ~500 mA∙h g-1, and an energy density of about 20 mW∙h cm-2. Conclusion In summary, we report in the presentation a summary of our high-loading core-shell sulfur cathodes and the design of their application in the development of the lean-electrolyte lithium-sulfur cells. Our core-shell cathodes exhibit excellent electrochemical utilization and retention of active material in both solid and liquid state, which shows the long cycle life and long shelf life of the high energy density lithium-sulfur cell. Figure 1. Illustration of a lithium-sulfur cell with the core-shell cathode equipped with sulfur, polysulfide, and sulfide cores. References -C. Wu, S.-H. Chung, J. Mater. Chem. A 2023, 10.1039/D3TA00210A.-H. Chung, A. Manthiram, Adv. Energy Mater. 2017, 7, 1700537.-H. Chung, A. Manthiram, Energy Environ. Sci. 2016, 9, 3188. Figure 1

Toward Stimulating the Chemistry Process for Garnet Electrolyte-Based Molten Li-S Batteries: Modulation of the End-Product in the Cathode with High Loading.

Due to their low self-discharge rate, no intermediate product dissolution in the cathode, and easy recycle of electrode materials, solid electrolyte-based molten lithium sulfur batteries can be one of the highly anticipated advanced electrochemical chemistry technologies for grid-scale energy storage. However, the actual energy density and reversibility of them still face severe challenges for low active materials loading and the inherent low conductivity of sulfur and its end-products. In this work, with the iodide modulation effect, small size (∼5 nm for the primary particles) and low relative crystallinity discharge end-products in the sulfur cathode can be formed, contributing to the immense specific capacity and reversibility. As validated by theoretical calculations, iodide ions in the homogeneous molten composite cathode display a profound comprehensive effect on the chemical reaction and cycling stability. As a result, high sulfur loading (over 80 mg cm-2) with a significant utilization rate can be achieved, corresponding to a single Li-S cell of 1.39 Ah and a volumetric energy density of 528.5 Wh L-1 based on the overall cell volume; simultaneously, a prominent cycling stability during 300 cycles along with an impressive reversibility is obtained.

Synergistic Desulfurization Performance of Industrial Waste Red Mud: A Comprehensive Experimental and Computational Study for COS Removal and CO(g) Production

The desulfurization process is crucial to produce high-purity hydrogen from natural gas because the gas contains sulfur compounds, which triggers the corrosion of tanks and pipes, and deactivates hydrogen fuel cell catalysts. This study evaluated experimentally and computationally the desulfurization performance of industrial waste red mud. The experimental results show that red mud has an outstanding performance in COS desulfurization, in which the sulfur capacity was larger than that for Fe2O3 by 146–156 %. The experimentally observed high performance originated from the synergetic effects between the main active phase of Fe2O3 and another element (Ti). Interestingly, the red mud provides the catalytic behavior producing CO(g) with deposited solid sulfur during the desulfurization reaction. Computational analysis proposed that the Ca/Fe2O3 phase plays a critical role in the catalytic behavior of COS decomposition. Adsorbed CO and S weakly bind on the Ca/Fe2O3 surface compared to the other phases. Based on the results, red mud has a strong potential to be a desulfurization absorber and COS decomposition catalyst. In addition, these findings provided initial insights into the development of the new low-cost sulfur absorber (Ti substituted Fe2O3) and COS decomposition catalyst (Ca substituted Fe2O3), producing the value-added product of CO(g) from COS(g).

INCREASING THE EXTRACTION OF VACUUM GAS OIL AT THE ELOU-AVT UNIT

The ELOU-AVT unit is part of a large oil refining complex. This unit is designed for primary processing of oils from various fields, as well as their mixtures. Refining is carried out in order to separate oil into separate fractions (gasoline, kerosene, diesel fuel, fuel oil), which are used as raw materials for secondary oil refining at other units. On the territory of modern refineries, in order to increase the depth of processing of petroleum feedstock, in most cases the following technological units are used: – The isomerization unit is designed for the production of low-boiling high-octane isomerizate used as a component of unleaded motor gasolines. For the production of a low-boiling high-octane component, the plant uses the process of low-temperature isomerization of C5-C6 normal paraffins. – The distillate hydrotreating unit is designed to produce high-quality diesel fuel with low sulfur and nitrogen content, high cetane number, and improved low-temperature properties. – The sulfur production unit is designed to produce solid commercial sulfur by the oxidative conversion of hydrogen sulfide into elemental sulfur. The delayed coking unit is designed to process heavy oil residues (straight-run tar) into lighter gaseous, liquid products and petroleum coke. The process of thermal cracking is the basis for the processing of tar. – The catalytic reformer with preliminary hydrotreatment is designed for the processing of gasoline fractions of oil in order to obtain high-quality gasolines and aromatic hydrocarbons, as well as hydrogen-containing gas (HCG), which is widely used both in petrochemistry and in such oil refining processes as: hydrotreating, hydrocracking, isomerization, etc. Oil refining is a multi-stage process of physical and chemical processing of crude oil, which results in the production of a complex of petroleum products. Industrial primary distillation units are divided into atmospheric (AT), vacuum (VT) and combined (for example, AVT, CDU-AVT, etc.). It is impossible to obtain a single marketable oil product from crude oil directly by one process (with the exception of gases), all of them are obtained by sequential processing at several installations. Keywords: ELOU-AVT machine, distillate hydrotreating unit, Oil refining, multi-stage process, primary distillation units

Transformation and migration mechanism of carbon and sulfur in lignite’s chemical looping gasification using carbide slag

In the process of lignite’s chemical looping gasification using carbide slag, carbon, and sulfur are present in both the gas and solid phases. To analyze the migration and transformation of carbon and sulfur in lignite’s chemical looping gasification using carbide slag, theoretical calculations along with experiments were conducted. The results showed that the migration transformation of carbon consisted of three main parts. First part was the transformation of organic carbon to inorganic gaseous carbon, which was followed by the mutual transformation of inorganic gaseous carbon. Finally, the inorganic carbon in gas was transformed into solid phase. The transformation of gaseous inorganic carbon to solid inorganic carbon, and that of inorganic carbon to gaseous carbon occurred at the reaction temperature of more than 1073 K. During the reaction, the migration transformation of sulfur consisted of two main steps. The transformation of organic sulfur to inorganic gaseous sulfur (H2S) through lignite’s gasification, and the transformation of inorganic gaseous sulfur (H2S) to inorganic solid sulfur (CaS). In-situ solidification of sulfur could be achieved through lignite-H2S-CaS reaction. This work provides fundamental knowledge about the mechanism of the transformation of carbon and sulfur during lignite’s chemical looping gasification and provides support for controlling the in-situ solidification of sulfur and carbon-containing gases during lignite’s chemical looping gasification using carbide slag.

Interplay between energy and geometry of parallel-displaced interactions in S8 dimer structures

Elemental sulfur exists in various allotropes, with the most stable form being the cyclic S8 allotrope. Although the orthorhombic α-S8 modification has been extensively studied, there has been no systematic analysis of noncovalent interactions between sulfur rings and their nature, geometries, and energies until now. To achieve this, we conducted a comprehensive study analyzing all crystal structures from the Cambridge Structural Database involving contacts between S8 molecules. Then, we combined those data with high-level quantum chemical calculations. The results revealed that the preferred orientation in the crystal structures is parallel-displaced. Quantum chemical calculations supported this finding, demonstrating that the most stable interaction in the S8 dimer occurs when two molecules adopt a parallel-displaced geometry resembling the one observed in the crystal structures. The interaction in the S8 dimer is very strong, with an energy of −8.70 kcal/mol, calculated at a highly accurate CCSD(T)/CBS level. In this stacking-like geometry, multiple S…S interactions can form, and the NCI analysis indicated an overlap of large surfaces of interacting molecules, significantly contributing to the system's stability. The SAPT2+(3) energy decomposition analysis showed that the predominant attractive force between two S8 molecules is dispersion, although the electrostatic component is also significant. This research holds importance in understanding the molecular assembly in solid sulfur and in systems that exhibit interactions between S8 molecules.

Bottom-trawling signals lost in sediment: A combined biogeochemical and modeling approach to early diagenesis in a perturbed coastal area of the southern Baltic Sea

Trawl-fishing is broadly considered to be one of the most destructive anthropogenic activities toward benthic ecosystems. In this study, we examine the effects of bottom-contact fishing by otter trawls on the geochemistry and macrofauna in sandy silt sediment in an area of the Baltic Sea where clear spatial patterns in trawling activity were previously identified by acoustic mapping. We calibrated an early diagenetic model to biogeochemical data from various coring locations. Fitting measured mercury profiles allowed for the determination of the sediment mixing and burial velocity. For all sites, independent of the trawl mark density, good fits were obtained by applying the model with the same organic matter loading and parameter values, while iron fluxes scaled linearly with the burial velocity. A sensitivity analysis revealed that the fitted sulfate reduction rate, solid sulfur contents, ammonium concentration, and both the isotopic composition and concentration of dissolved inorganic carbon provided reliable constraints for the total mineralization rate, which exhibited a narrow range of variability (around ±20 % from the mean) across the sites. Also, the trawling intensity did not significantly correlate with total organic carbon contents in surficial sediment, indicating limited loss of organic matter due to trawling. The fits to the reactive iron, acid volatile sulfur, chromium(II) reducible sulfur contents, and porewater composition demonstrate that sediment burial and mixing primarily determine the redox stratification. The mixing depth did not correlate with trawling intensity and is more likely the result of bioturbation, as the analyzed macrofaunal taxonomy and density showed a high potential for sediment reworking. The extraordinarily long-lived Arctica islandica bivalve dominated the infaunal biomass, despite the expectation that trawling leads to the succession from longer-lived to shorter-lived and bigger to smaller macrofauna. Our results further suggest that a clear geochemical footprint of bottom-trawling may not develop in sediments actively reworked by tenacious macrofauna.

Superlattice and defect engineering enabled NC@VS2–x as trifunctional promoter for polysulfides catalytic conversion

The shuttling effect and sluggish reaction kinetics of the intermediate lithium polysulfides (LiPSs) are the main barriers limiting the application of Li–S batteries. Herein, superlattice and sulfur-vacancy engineering are concurrently constructed in the N-doped carbon embedded VS2 (NC@VS2–x) for LiPSs catalytic conversion. The superlattice and defect engineering with NC imbedded produce high activity trapping sites, enhance the electronic conductivity, and provide fast Li diffusion channels, achieving the massive precipitation of Li2S, promoting the dissolution of solid sulfur species, and accelerating the Li ions transport. Therefore, the trifunctional LiPSs promoter in Li–S cell yields high rate performance (4.0 C) and a low capacity decay rate of 0.036% at 2.0 C. Impressively, the NC@VS2–x cell delivers a capacity of 5.15 mA h cm−2 with S loading of 6.2 mg cm−2 and lean E/S ratio of 4.0 µL mg−1. When assembled in the pouch cell, the NC@VS2–x electrode can work well over 45 cycles, indicating a potential application in practical Li–S batteries. The proposed dual-engineering strategy to form the trifunctional promoter is anticipated to be applied in other multielectron energy related systems.

Optimizing Sulfur Utilization in High Loading Cathode for All-Solid-State Lithium-Sulfur Battery

All Solid-state Lithium-Sulfur battery (ASSLSB) possesses a great promise in providing a safe, high energy density, and low cost battery technology for vehicle electrification and grid energy storage. To achieve practically high specific energy in ASSLSB (e.g., >400 Wh/Kg), sulfur cathodes with high areal capacity (>6 mAh cm-2) are essentially needed to offset the relatively low working voltage of elemental sulfur cathode (1.9 V vs. Li). This requires high mass loading sulfur cathodes by maximizing both sulfur content in the whole electrode and sulfur utilization rate to reduce the parasitic weights. An optimal electrode architecture featuring sufficiently connected sulfur/solid electrolyte/carbon triple interfaces is desired to enable sulfur’s fast accessibility to electron and Li-ion simultaneously. Due to the non-flowability of those three solid components, however, it is very hard to maximize the contact of trip solid phases, which need new insights of the materials design and processing technology.This work looks at carbon microstructures and their impact on triple-point contact between electrochemically active sulfur, carbon, and the solid-state electrolyte (SSE) that comprises most composite cathodes in ASSLSB systems. While significant work has gone into understanding and developing novel carbon host structures for liquid Li-S cells for improving sulfur utilization, polysulfide trapping, better understanding is needed for ASSLSBs. Specifically, how sulfur infiltration, loading, and spatial distribution within the porous carbon host impacts sulfur utilization. Understanding how the infiltrated sulfur that resides in the porous carbon host connects with both carbon and solid electrolyte networks across the whole electrode structure and maintains its robustness during the repeated cell cycling is needed to achieve full utilization in high sulfur loading electrodes. The solid sulfur cathode system examined in the present study is a composite of porous carbon, sulfur, and a sulfide-based solid electrolyte. A combination of porous carbon hosts is investigated and correlated to the cell performance at practical conditions. Advanced characterization and computational tools are used to further elucidate the key parameters for high sulfur utilization in ASSLSBs with high sulfur loading cathodes. Details of the study will be presented and discussed at the meeting.Reference:(1) Nagata, H. and Y. Chikusa (2016). "All-Solid-State Lithium–Sulfur Battery with High Energy and Power Densities at the Cell Level." Energy Technology 4(4): 484-489(2) Banerjee, A., et al. (2020). "Interfaces and Interphases in All-Solid-State Batteries with Inorganic Solid Electrolytes." Chemical Reviews 120(14): 6878-6933.

High-Performance Lithium-Sulfur Batteries via Molecular Complexation.

Beyond lithium-ion technologies, lithium-sulfur batteries stand out because of their multielectron redox reactions and high theoretical specific energy (2500 Wh kg-1). However, the intrinsic irreversible transformation of soluble lithium polysulfides to solid short-chain sulfur species (Li2S2 and Li2S) and the associated large volume change of electrode materials significantly impair the long-term stability of the battery. Here we present a liquid sulfur electrode consisting of lithium thiophosphate complexes dissolved in organic solvents that enable the bonding and storage of discharge reaction products without precipitation. Insights garnered from coupled spectroscopic and density functional theory studies guide the complex molecular design, complexation mechanism, and associated electrochemical reaction mechanism. With the novel complexes as cathode materials, high specific capacity (1425 mAh g-1 at 0.2 C) and excellent cycling stability (80% retention after 400 cycles at 0.5 C) are achieved at room temperature. Moreover, the highly reversible all-liquid electrochemical conversion enables excellent low-temperature battery operability (>400 mAh g-1 at -40 °C and >200 mAh g-1 at -60 °C). This work opens new avenues to design and tailor the sulfur electrode for enhanced electrochemical performance across a wide operating temperature range.

Advancing Power Supply Devices for Electric Aircraft

The pollution caused by the construction of more aircraft that run on fuel will become more severe as more fuel-energy aircraft are built. As a result of the numerous environmental crises currently confronting the world, electric jumbo jets need to replace those that run on fuel. Note that the most interesting issue would be the airplane's power supplies. Research is conducted on the physical principles underpinning solar panels and power beaming. Batteries are an essential component of electric aircraft. The materials used to construct airplane batteries are among the most crucial aspects of battery design, and lithium-ion batteries are among the top options available. The capacity of the batteries will not decrease over time, and they will not catch fire or put passengers at risk. In order to maintain charging, a one-of-a-kind combination of sulfur and selenium is utilized. It has been discovered that solid sulfur selenium batteries have a good touch, do not ignite, are thinner (even thinner than lithium-ion batteries), and have a higher capacity for storing energy than lithium-ion batteries.

Spatial and temporal distribution of hydrogen sulfide and sulfur species in coastal marine sediments collected from Osaka Bay, Japan

The identification of sulfur species in coastal marine sediments provides insight into the sulfur cycle in coastal seas. This study revealed the spatial and temporal distribution of hydrogen sulfide in the sediment pore water and sulfur species in the marine sediments in Osaka Bay, Japan using a combination of detection tubes with the formation of a color band of lead sulfide and X-ray absorption fine structure spectroscopy to identify sulfur species. The sulfur species present in the sediment in this study were somewhat affected by the sediment pore water, and the solid sulfur species identified in the surface sediments were sulfate, thiosulfate, elemental sulfur, and pyrite. These results revealed that the process of change in the sulfur species in the sediments could be categorized into three subprocesses. (1) Hydrogen sulfide was generated in the sediment pore water and scavenged by oxidation into sulfur and pyrite formation. Pyrite was successively oxidized into thiosulfate and sulfate when the dissolved oxygen in the bottom water was sufficient. (2) When the dissolved oxygen was depleted at the innermost part of the Bay in October and November, pyrite might have been oxidized into sulfate by iron and manganese in the sediment. (3) For the western and southern parts of the Bay, because vertical mixing supplies oxygen to the seabed, the formation and oxidative scavenging of hydrogen sulfide in the sediment pore water was balanced. Thus, the hydrogen sulfide in the sediment pore water remained undetected.