Sulfur Conversion Research Articles

Quasi‐Solid Sulfur Conversion for Energetic All‐Solid‐State Na−S Battery

AbstractThe high theoretical energy density (1274 Wh kg−1) and high safety enable the all‐solid‐state Na−S batteries with great promise for stationary energy storage system. However, the uncontrollable solid–liquid‐solid multiphase conversion and its associated sluggish polysulfides redox kinetics pose a great challenge in tunning the sulfur speciation pathway for practical Na−S electrochemistry. Herein, we propose a new design methodology for matrix featuring separated bi‐catalytic sites that control the multi‐step polysulfide transformation in tandem and direct quasi‐solid reversible sulfur conversion during battery cycling. It is revealed that the N, P heteroatom hotspots are more favorable for catalyzing the long‐chain polysulfides reduction, while PtNi nanocrystals manipulate the direct and full Na2S4 to Na2S low‐kinetic conversion during discharging. The electrodeposited Na2S on strongly coupled PtNi and N, P‐codoped carbon host is extremely electroreactive and can be readily recovered back to S8 without passivation of active species during battery recharging, which delivers a true tandem electrocatalytic quasi‐solid sulfur conversion mechanism. Accordingly, stable cycling of the all‐solid‐state soft‐package Na−S pouch cells with an attractive specific capacity of 876 mAh gS−1 and a high energy of 608 Wh kgcathode−1 (172 Wh kg−1, based on the total mass of cathode and anode) at 60 °C are demonstrated.

Strengthening d‐p Orbital‐Hybridization via Coordination Number Regulation of Manganese Single‐Atom Catalysts Toward Fast Kinetic and Long‐Life Sodium–Sulfur Batteries

AbstractThe practical application of room‐temperature sodium‐sulfur (RT Na–S) batteries is blocked by the notorious shuttle effect of sodium polysulfides (NaPSs) and sluggish refox reaction kinetics. Single‐atom catalysts (SACs) have been widely studied for boosting the energy storage performance of RT Na‐S batteries. Nevertheless, the catalytic centers of SACs reported so far have focused mainly on symmetrical metal–N4 structures, which offer weak bonding affinity toward polar NaPSs, leading to detrimental shuttle effect and sluggish sulfur conversion kinetics. Herein, a novel asymmetrical Mn–N2 structure is implanted into nitrogen‐doped carbon nanofibers (Mn‐N2/CNs) through thermal NH3 etching of a symmetrical Mn–N2O2 structure. The Mn–N2 structure promotes the bonding affinity and catalytic conversion of NaPSs due to the strengthened d‐p orbital‐hybridization between the d orbital of Mn in the Mn–N2 structure and the p orbital of S in NaPSs. Consequently, Mn‐N2/CNs@S achieves a high capacity of 458 mAh g−1 at 3.0 C with a capacity decay of 0.23% over 2300 cycles. This work offers a promising pathway for regulating the coordination number of SACs with strengthened d‐p orbital‐hybridization for high‐performance RT Na–S batteries.

The impact of reduced sulfur compounds on aerobic granular sludge formation and biological phosphorus removal

Biological sulfur conversion combined with phosphorus removal represents an innovative biotechnology for activated sludge (AS). However, its effect on the formation of aerobic granular sludge (AGS) remains unclear. This study aimed at determining the impact of sulfide and thiosulfate on the performance of enhanced biological phosphorus removal (EBPR) and on AGS formation. Using two lab-scale sequencing batch reactors (SBR), we compared EBPR performance, the degree of granulation, and the enriched microbial community with sulfide (SBR-S, 20 mg S/L) or thiosulfate (SBR-T, 140 mg S/L) as primary sulfur source. Results indicate that both reactors achieved comparable EBPR performance, with a phosphorus removal rate of 98% in SBR-T and 99% in SBR-S. SBR-T resulted in compact granules with fast settling properties, while SBR-S resulted in dense floccular sludge, referred to as “densified sludge”. Both systems enriched a comparable microbial community with shared dominant genera, including Ca. Competibacter, Thiothrix, Ca. Accumulibacter and Dechloromonas. The higher abundance of Thiothrix unzii throughout the operating time in SBR-T, reaching 19.4%, is believed to have enhanced the granulation process. This study provides important insight into the role of reduced sulfur compounds in sludge densification and EBPR performance, relevant to sulfur-rich wastewaters such as those from industrial sources.

Synergetic catalytic regulation of nitrogen doped NiS2/CoS2 heterostructure for polysulfide immobilization in Li-S batteries

The sluggish kinetics of sulfur species conversion and the shuttle effect in lithium-sulfur batteries are severely hindered in practical applications. Herein, we propose nitrogen doped NiS2/CoS2 heterostructure supported on CNT (N-NiS2/CoS2/CNT) by simple thiourea pyrolysis served as electrocatalyst functionalized on PP separator. The new formed M-N bonds on N-NiS2/CoS2/CNT motivate the catalytic activity of metal active centers strengthening the chemical anchoring towards polysulfides and Li2S electrodeposition behavior. The N,S dual doping on CNT support synergistically affords the electrochemical active sites for polysulfides conversion kinetics and increases the electrical conductivity of the whole catalyst. In Li-S batteries, the initial capacity of the battery with N-NiS2/CoS2/CNT functionalized separators reaches 1317.3 mAh g−1 at 0.2 C, and after 200 cycles, the capacity reaches 939.5 mAh g−1 with a capacity retention rate of 59.8%. Even at a large multiplicity rate of 2 C, the capacity can still be maintained at 552.2 mAh g−1 with a low-capacity decay of 0.068% after 500 cycles.

Catalytic Solid‐State Sulfur Conversion Confined in Micropores toward Superhigh Coulombic Efficiency Lithium‐Sulfur Batteries

AbstractAchieving the solid–solid conversion of sulfur is a fundamental solution to eliminating the shuttling of soluble polysulfides and improving the cycling stability of lithium‐sulfur batteries. However, the sluggish solid reaction kinetics seriously challenge the battery performance. In this work, a micropore‐confined catalysis strategy to achieve the smooth solid–solid conversion of sulfur is proposed. It is realized by storing sulfur in a microporous carbon host with narrow pore size and uniformly distributed single‐atom Co catalytic sites. The microporous structure avoids the contact of electrolyte solvents with the inner sulfur, preventing the formation and dissolution of polysulfides and efficiently suppressing sulfur loss during cycling. The introduced single‐atom Co catalytic sites promote the charge transfer to accelerate the solid–solid conversion of sulfur. When coupled with a liquid carbonate electrolyte, the battery exhibits a remarkably high Coulombic efficiency (CE) of ≈99.88% and a minimal capacity decay rate of ≈0.016% per cycle for 1000 cycles at 0.5 C. Even when coupled with the solid‐state electrolyte, the battery still delivers a significantly high capacity of 1100 mAh g−1 and a remarkably high CE of ≈99.83% over 200 cycles. This work reveals a promising solution for developing practical stable Li─S batteries.

Multifunctional Heterostructured Fe3O4-FeTe@MCM Electrocatalyst Enabling High-Performance Practical Lithium-Sulfur Batteries Via Built-in Electric Field.

The development of capable of simultaneously modulating the sluggish electrochemical kinetics, shuttle effect, and lithium dendrite growth is a promising strategy for the commercialization of lithium-sulfur batteries. Consequently, an elaborate preparation method is employed to create a host material consisting of multi-channel carbon microspheres (MCM) containing highly dispersed heterostructure Fe3O4-FeTe nanoparticles. The Fe3O4-FeTe@MCM exhibitsa spontaneous built-in electric field (BIEF) and possesses both lithophilic and sulfophilic sites, rendering it an appropriate host material for both positive and negative electrodes. Experimental and theoretical results reveal that the existence of spontaneous BIEF leads to interfacial charge redistribution, resulting in moderate polysulfide adsorption which facilitates the transfer of polysulfides and diffusion of electrons at heterogeneous interfaces. Furthermore, the reduced conversion energy barriers enhanced the catalytic activity of Fe3O4-FeTe@MCM for expediting the bidirectional sulfur conversion. Moreover, regulated Li deposition behavior is realized because of its high conductivity and remarkable lithiophilicity. Consequently, the battery exhibited long-term stability for 500 cycles with 0.06% capacity decay per cycle at 5 C, and a large areal capacity of 7.3mAhcm-2 (sulfur loading: 9.73mgcm-2) at 0.1 C. This study provides a novel strategy for the rational fabrication of heterostructure hosts for practical Li-S batteries.

A Synthetic Microbiome Based on Dominant Microbes in Wild Rice Rhizosphere to Promote Sulfur Utilization

Sulfur (S) is one of the main components of important biomolecules, which has been paid more attention in the anaerobic environment of rice cultivation. In this study, 12 accessions of rice materials, belonging to two Asian rice domestication systems and one African rice domestication system, were used by shotgun metagenomics sequencing to compare the structure and function involved in S cycle of rhizosphere microbiome between wild and cultivated rice. The sulfur cycle functional genes abundances were significantly different between wild and cultivated rice rhizosphere in the processes of sulfate reduction and other sulfur compounds conversion, implicating that wild rice had a stronger mutually-beneficial relationship with rhizosphere microbiome, enhancing sulfur utilization. To assess the effects of sulfate reduction synthetic microbiomes, Comamonadaceae and Rhodospirillaceae, two families containing the genes of two key steps in the dissimilatory sulfate reduction, aprA and dsrA respectively, were isolated from wild rice rhizosphere. Compared with the control group, the dissimilatory sulfate reduction in cultivated rice rhizosphere was significantly improved in the inoculated with different proportions groups. It confirmed that the synthetic microbiome can promote the S-cycling in rice, and suggested that may be feasible to construct the synthetic microbiome step by step based on functional genes to achieve the target functional pathway. In summary, this study reveals the response of rice rhizosphere microbial community structure and function to domestication, and provides a new idea for the construction of synthetic microbiome.

Organic Electrolyte Additive: Dual Functions Toward Fast Sulfur Conversion and Stable Li Deposition for Advanced Li-S Batteries.

Lithium-sulfur (Li-S) battery is of great potential for the next generation energy storage device due to the high specific capacity energy density. However, the sluggish kinetics of S redox and the dendrite Li growth are the main challenges to hinder its commercial application. Herein, an organic electrolyte additive, i.e., benzyl chloride (BzCl), is applied as the remedy to address the two issues. In detail, BzCl can split into Bz· radical to react with the polysulfides, forming a Bz-S-Bz intermediate, which changes the conversion path of S and improves the kinetics by accelerating the S splitting. Meanwhile, a tight and robust solid electrolyte interphase (SEI) rich in inorganic ingredients namely LiCl, LiF, and Li2O, is formed on the surface of Li metal, accelerating the ion conductivity and blocking the decomposition of the solvent and lithium polysulfides. Therefore, the Li-S battery with BzCl as the additive remains high capacity of 693.2mAhg-1 after 220 cycles at 0.5C with a low decay rate of 0.11%. This work provides a novel strategy to boost the electrochemical performances in both cathode and anode and gives a guide on the electrolyte design toward high-performance Li-S batteries.

Effective Bidirectional Mott-Schottky Catalysts Derived from Spent LiFePO4 Cathodes for Robust Lithium-Sulfur Batteries.

It is deemed as a tough yet profound project to comprehensively cope with a range of detrimental problems of lithium-sulfur batteries (LSBs), mainly pertaining to the shuttle effect of lithium polysulfides (LiPSs) and sluggish sulfur conversion. Herein, a Co2P-Fe2P@N-doped carbon (Co2P-Fe2P@NC) Mott-Schottky catalyst is introduced to enable bidirectionally stimulated sulfur conversion. This catalyst is prepared by simple carbothermal reduction of spent LiFePO4 cathode and LiCoO2. The experimental and theoretical calculation results indicate that thanks to unique surface/interface properties derived from the Mott-Schottky effect, full anchoring of LiPSs, mediated Li2S nucleation/dissolution, and bidirectionally expedited "solid⇌liquid⇌solid" kinetics can be harvested. Consequently, the S/Co2P-Fe2P@NC manifests high reversible capacity (1569.9mAhg-1), superb rate response (808.9mAhg-1 at 3C), and stable cycling (a low decay rate of 0.06% within 600 cycles at 3C). Moreover, desirable capacity (5.35mAhcm-2) and cycle stability are still available under high sulfur loadings (4-5mgcm-2) and lean electrolyte (8µLmg-1) conditions. Furthermore, the as-proposed universal synthetic route can be extended to the preparation of other catalysts such as Mn2P-Fe2P@NC from spent LiFePO4 and MnO2. This work unlocks the potential of carbothermal reduction phosphating to synthesize bidirectional catalysts for robust LSBs.

Controllable sulfur redox multi-pathway reactions regulated by metal-free electrocatalysts anchored with LiS3* radicals

Regulating sulfur redox kinetics is an effective strategy for addressing the critical issues in lithium-sulfur batteries and improving their comprehensive performance. However, the sluggish and complex sulfur reduction reaction (SRR) kinetics can seriously deteriorate the electrochemical performance of lithium-sulfur batteries, hindering a clear comprehension of the electrocatalytic mechanism and presenting challenges for targeted design. Hence, it is crucial to elucidate the SRR mechanism and further refine the catalytic principle. In this study, the SRR mechanism and the pivotal role of radicals are comprehensively explored using ultrathin nitrogen-oxygen co-doped carbon nanosheets (UN/O-CNS) as an electrocatalytic model, combining density functional theory calculations with experimental techniques, such as X-ray absorption near-edge structure spectroscopy. The abundant N-O active sites of UN/O-CNS can synergistically anchor LiS3* radicals, facilitating efficient multi-pathway sulfur conversion. Additionally, UN/O-CNS can capture and catalyze polysulfides while also bi-directionally catalyzing Li2S. The S@UN/O-CNS cells ultimately demonstrate ultra-long cycling performance and high load capacity. The successful operation in pouch cells validates the practical effectiveness of UN/O-CNS. Overall, this study offers novel insights into the complexity and potential pathways of sulfur redox reaction, providing new perspectives for exploring the catalytic mechanism of cost-effective metal-free electrocatalysts.

Facilitating the Electrochemical Oxidation of ZnS through Iodide Catalysis for Aqueous Zinc-Sulfur Batteries.

Aqueous zinc-sulfur (Zn-S) batteries show great potential for unlocking high energy and safety aqueous batteries. Yet, the sluggish kinetic and poor redox reversibility of the sulfur conversion reaction in aqueous solution challenge the development of Zn-S batteries. Here, we fabricate a high-performance Zn-S battery using highly water-soluble ZnI2 as an effective catalyst. In situ experimental characterizations and theoretical calculations reveal that the strong interaction between I- and the ZnS nanoparticles (discharge product) leads to the atomic rearrangement of ZnS, weakening the Zn-S bonding, and thus facilitating the electrochemical oxidation reaction of ZnS to S. The aqueous Zn-S battery exhibited a high energy density of 742 Wh kg(sulfur) -1 at the power density of 210.8 W kg(sulfur) -1 and good cycling stability over 550 cycles. Our findings provide new insights about the iodide catalytic effect for cathode conversion reaction in Zn-S batteries, which is conducive to promoting the future development of high-performance aqueous batteries.

Facilitating the Electrochemical Oxidation of ZnS through Iodide Catalysis for Aqueous Zinc‐Sulfur Batteries

AbstractAqueous zinc‐sulfur (Zn‐S) batteries show great potential for unlocking high energy and safety aqueous batteries. Yet, the sluggish kinetic and poor redox reversibility of the sulfur conversion reaction in aqueous solution challenge the development of Zn‐S batteries. Here, we fabricate a high‐performance Zn‐S battery using highly water‐soluble ZnI2 as an effective catalyst. In situ experimental characterizations and theoretical calculations reveal that the strong interaction between I− and the ZnS nanoparticles (discharge product) leads to the atomic rearrangement of ZnS, weakening the Zn‐S bonding, and thus facilitating the electrochemical oxidation reaction of ZnS to S. The aqueous Zn‐S battery exhibited a high energy density of 742 Wh kg(sulfur)−1 at the power density of 210.8 W kg(sulfur)−1 and good cycling stability over 550 cycles. Our findings provide new insights about the iodide catalytic effect for cathode conversion reaction in Zn‐S batteries, which is conducive to promoting the future development of high‐performance aqueous batteries.

Microbial Conversion of Sulfur-Containing Compounds Contributed the Natural Biodegradation of Bituminous Coals

Microorganisms can affect coal biodegradation by driving elemental biogeochemical cycling. A detailed description of the sulfur conversion process led by indigenous bacteria during coal degradation is important. This study obtained sulfur-containing compounds conversion bacteria through indoor enrichment and conducted anaerobic culture experiments using coal supplemented with enriched bacteria. The study showed that the addition of enriched bacteria changed the microbial composition, particularly the microbial groups within Pseudomonadota and Bacillota. In addition, the sulfur-containing compounds conversion bacteria increased the pore volume and specific surface area of micropores (<10 nm) and transition pores (10–100 nm), as well changed the content of sulfur-containing organic components including polypeptides, aromatic compounds, alkyl compounds, and thiazoles. The genera related to inorganic sulfur conversion were mainly belonging to Bacillota and Actinomycetota. Additionally, functional genera that can degrade sulfur-containing organic compounds of dibenzothiophenes through the ring-opening of benzene rings were found within Pseudomonadota, Bacillota and Actinomycetota. In summary, organic sulfur-related Pseudomonadota, Bacillota and Actinomycetota and inorganic sulfur-related Bacillota and Actinomycetota detected in this study could accelerate the sulfur-containing compounds conversion and ultimately increase micropores in coal, and this holds great significance for understanding the biogeochemical cycling process of coal.

Accelerated Li2S conversion in sparingly-solvating electrolytes enabled with dipole-dipole interaction for wide-temperature Li-S batteries

Utilizing sparingly-solvating electrolytes (SSEs), which suppress the dissolution of lithium polysulfides (Li2S4−8, LPSs), could reduce electrolyte consumption and thus retrieve the energy density competitiveness of lithium-sulfur batteries (LSBs). However, SSEs-based LSBs suffer from sluggish kinetics and rapid capacity degradation due to the accumulation of Li2S in the cathode. The catalytic approach, which is widely used to promote the sulfur conversion in ether-based LSBs, is rarely explored in SSEs-based LSBs due to the lack of a catalyst workable in the absence of dissolved LPSs. Here, by embedding CuS nanoparticles, which have high dipole-dipole interaction with Li2S, as polar sites into the carbon matrix of the sulfur cathode, we homogenize the Li2S deposition and accelerate the conversion kinetics. As a result, the cell with S/KB@CuS cathode realized a remarkable initial discharge capacity of 1469.5 mAh g−1 (87.7% of the theoretical value) with a reduced polarization potential (0.526V). Even at a low temperature of −15°C, the cell with S/KB@CuS cathode still delivered a capacity-retention of 799.0 mAh g−1 after 100 cycles. More importantly, the universality of the as-proposed dipole-dipole-interaction strategy is demonstrated with many other SSEs and polar additives.

Efficient nickel extraction from nickel matte by combined atmospheric-oxygen pressure acid leaching: Thermodynamic analysis and sulfur conversion mechanism

Atmospheric acid leaching was prevalently employed in extraction nickel from nickel matte owing to its gentle effect, but the leaching efficiency of nickel still remains limited. In this paper, the efficient nickel leaching from nickel matte and sulfur conversion mechanism through the combined atmospheric-oxygen pressure acid leaching process were investigated. Factors affecting nickel leaching and sulfur conversion from nickel matte were systematically investigated on the basis of thermodynamic calculations. The results showed that the nickel leaching rate after atmospheric acid leaching could reach 79.91 % under the optimized conditions of H2SO4 concentration of 300 g/L, H2O2 dosage of 7 %, 80 °C, liquid–solid ratio of 8 mL/g, and 3 h. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM-EDS) analyses indicated that the S8-coating produced during atmospheric acid leaching and the small amount of NiO passivation film on the surface of the nickel matte impeded the further leaching of nickel. The S8-coating and NiO passivation film were converted to H2SO4 and water-soluble NiSO4, respectively, after the oxygen pressure leaching process. The Ni3S2 and NiS in the nickel matte were released to continue leaching, and the nickel extraction rate reached 99.11 %. The specific optimized process parameters were H2SO4 concentration of 90 g/L, operating pressure of 1.5 MPa, 180 °C, L/S of 10 mL/g and 3 h. This provided a green economical and efficient method for the extraction of nickel from nickel matte.

Anion-Regulated Sulfur Conversion in High-Content Carbon Layer Confined Sulfur Cathode Maximizes Voltage and Rate Capability of K-S Batteries.

Potassium-sulfur (K-S) batteries have attracted attention in large-scale energy storage systems. Small-molecule/covalent sulfur (SMCS) can help to avoid the shuttle effect of polysulfide ions via solid-solid sulfur conversion. However, the content of SMCS is relatively low (≤40%), and solid-solid reactions cause sluggish kinetics and low discharge potentials. Herein, SMCS is confined in turbo carbon layers with a content of ≈74.1wt% via a C/S co-deposition process. In the K-S battery assembled by using as-fabricated SMCS@C as cathode and KFSI-EC/DEC as an electrolyte, anion-regulated two-plateau solid-state S conversion chemistry and a novel high discharge potential plateau at 2.5-2.0V with a remarkable reversible capacity of 384mAhg-1 at 3Ag-1 after 1000 cycles are found. The SMCS@C||K full cell showed energy and power density of 72.8Whkg-1 and 873.2Wkg-1, respectively, at 3Ag-1. Mechanismstudiesrevealthat theenlarged carbon layer space enables the diffusion of K+-FSI-ion pairs, and the coulombic attraction between them accelerates their diffusion in SMCS@C. In addition, FSI-regulates sulfur conversion in situ inside thecarbon layers along a two-plateau solid-state reaction pathway, which lowers the free energy and weakens the S─S bond of intermediates, leading to faster and more efficient S conversion.

Novel pentagonal carbon-based materials as multifunctional electrodes in lithium-sulfur batteries, a theoretical study

The commercialization process of lithium-sulfur batteries (LISBs) is hindered by several problems, including low electroconductivity, the dissolution of lithium polysulfides (LiPSs) and sluggish charging-discharging kinetics. Recently, two-dimensional (2D) penta-furrow structures have emerged as a distinct family of 2D structures with low mass densities, which are predicted to accelerate redox kinetics and enable sulfur conversion. Here, several novel pentagonal carbon-based substrates, including penta-graphene (penta-G) and penta-B2C (C2N, C2P, C2Si, and N2C), were first investigated in LISBs based on density functional theory (DFT) calculations. It is found that the penta-G, penta-C2P and penta-C2Si have excellent anchoring ability and can greatly improve conductivity during the whole S8/LiPSs insertion, which can effectively suppress the shuttle effect. More importantly, penta-G, penta-C2P and penta-C2Si can reduce the free energy of sulfur reduction reactions to 0.63–0.68 eV and lower the energy barriers of electrochemical conversions to 0.82–1.57 eV (Li2S dissociation) and 0.05–0.14 eV (Li-ion diffusion), thereby enhancing catalytic conversion efficiency in the discharging/charging processes. In addition, penta-G showed a much smaller volume expansion (34 %) than the 80 % value for elemental sulfur and a considerable sulfur loading amount (53.78 wt%). Our findings demonstrate that metallic pentagonal carbon-based materials could be a potential LISBs cathode material with high performance.

High‐Content Carbon Layer Confined Small‐Molecule/Covalent Sulfur Cathode Enables Long‐Life Calcium–Sulfur Batteries in Hybrid‐Ion Electrolyte

AbstractCalcium‐sulfur (Ca‐S) battery is a promising candidate for large‐scale energy storage system. However, the development of long‐life room‐temperature Ca–S batteries is hindered by the lack of effective sulfur cathode and the incompatibility between electrodes and electrolytes, leading to irreversible sulfur conversion, inefficient calcium plating/stripping and improper cathode/anode‐electrolyte interfaces (CEI/SEI). Herein, a turbo carbon layer confined small‐molecule/covalent sulfur cathode (S@C NS) with a record‐high content of 65.7% and enlarged carbon layer space is prepared via a C/S co‐deposition process. By using such a cathode and optimizing interfacial electrochemistry in LiPF6/Ca(BF4)2‐based hybrid electrolyte, a record‐breaking long‐life room‐temperature Ca‐S battery is reported. The capacity reaches 824.6 mAh g−1 at 100 mA g−1 with a retention of 47.9% after 145 cycles, and 462.1 mAh g−1 at even 500 mA g−1. Mechanism studies demonstrated that a Li/Ca‐based hybrid CEI with porous microstructure is found to facilitate the transfer kinetics of Ca2+ across the CEI; Turbo carbon layers with large inter‐layer space and their strong confinement on small‐molecule sulfur enabled reversible solid‐state sulfur conversion in situ inside the cathode; An effective Li/Ca‐based hybrid SEI formed on anode, allowing reversible Ca plating/stripping with low deposition potential and small overpotential.

Binary Atomic Sites Enable a Confined Bidirectional Tandem Electrocatalytic Sulfur Conversion for Low-Temperature All-Solid-State Na-S Batteries.

The broader implementation of current all-solid-state Na-S batteries is still plagued by high operation temperature and inefficient sulfur utilization. And the uncontrollable sulfur speciation pathway along with the sluggish polysulfide redox kinetics further compromise the theoretical potentials of Na-S chemistry. Herein, we report a confined bidirectional tandem electrocatalysis effect to tune polysulfide electrochemistry in a novel low-temperature (80 °C) all-solid-state Na-S battery that utilizes Na3 Zr2 Si2 PO12 ceramic membrane as a platform. The bifunctional hollow sulfur matrix consisting binary atomically dispersed MnN4 and CoN4 hotspots was fabricated using a sacrificial template process. Upon discharge, CoN4 sites activate sulfur species and catalyze long-chain to short-chain polysulfides reduction, while MnN4 centers substantially accelerate the low-kinetic Na2 S4 to Na2 S directly conversion, manipulating the uniform deposition of electroactive Na2 S and avoiding the formation of irreversible products (e.g., Na2 S2 ). The intrinsic synergy of two catalytic centers benefits the Na2 S decomposition and minimizes its activation barrier during battery recharging and then efficiently mitigate the cathodic passivation. As a result, the stable cycling of all-solid-state Na-S cell delivers an attractive reversible capacity of 1060 mAh g-1 with a high CE of 98.5 % and a high energy of 1008 Wh kgcathode -1 , comparable to the liquid electrolyte cells.

Effects of operating conditions on the in situ control of sulfur-containing odors by using a novel alternative landfill cover and its transformation mechanism.

Sulfur-containing gases are main sources of landfill odors, which has become a big issue for pollution to environment and human health. Biocover is promising for treating landfill odors, with advantages of durability and environmental friendliness. In this study, charcoal sludge compost was utilized as the main effective component of a novel alternative landfill cover and the in situ control of sulfur-containing odors from municipal solid waste landfilling process was simulated under nine different operating conditions. Results showed that five sulfur-containing odors (hydrogen sulfide, H2S; methyl mercaptan, CH3SH; dimethyl sulfide, CH3SCH3; ethylmercaptan, CH3CH2SH; carbon disulfide, CS2) were monitored and removed by the biocover, with the highest removal efficiencies of 77.18% for H2S, 87.36% for CH3SH, and 92.19% for CH3SCH3 in reactor 8#, and 95.94% for CH3CH2SH and 94.44% for CS2 in reactor 3#. The orthogonal experiment showed that the factors influencing the removal efficiencies of sulfur-containing odors were ranked from high to low as follows: temperature > weight ratio > humidity content. The combination of parameters of 20% weight ratio, 25°C temperature, and 30% water content was more recommended based on the consideration of the removal efficiencies and economic benefits. The mechanisms of sulfur conversion inside biocover were analyzed. Most organic sulfur was firstly degraded to reduced sulfides or element sulfur, and then oxidized to sulfate which could be stable in the layer as the final state. In this process, sulfur-oxidizing bacteria play a great role, and the distribution of them in reactor 1#, 5#, and 8# was specifically monitored. Bradyrhizobiaceae and Rhodospirillaceae were the dominant species which can utilize sulfide as substance to produce sulfate and element sulfur, respectively. Based on the results of OUTs, the biodiversity of these sulfur-oxidizing bacteria, these microorganisms, was demonstrated to be affected by the different parameters. These results indicate that the novel alternative landfill cover modified with bamboo charcoal compost is effective in removing sulfur odors from landfills. Meanwhile, the findings have direct implications for addressing landfill odor problems through parameter adjustment.