μL Mg-1 Research Articles

Strategically Engineered Metal Cluster-Rare Earth Oxide Heterojunction Catalyst for High-Performance Lean Electrolyte Lithium-Sulfur Batteries.

Developing high-energy-density lithium-sulfur batteries faces serious polysulfide shuttle effects and sluggish conversion kinetics, often necessitating the excessive use of electrolytes, which in turn adversely affects battery performance. Our study introduces a meticulously designed electrocatalyst, Cu-CeO2-x@N/C, to enhance lean-electrolyte lithium-sulfur battery performance. This catalyst, featuring in situ synthesized Cu clusters, regulates oxygen vacancies in CeO2 and forms Cu-CeO2-x heterojunctions, thereby diminishing sulfur conversion barriers and hastening reaction kinetics through the generation of S32-/S3*- intermediates. Besides, the three-dimensional conductive networks, composed of Cu and nitrogen-doped carbon matrices with high electrolyte affinity, effectively confine sparse electrolytes proximal to the catalyst locations, thereby facilitating rapid transport of Li+/electron to the active sites. As a result, the 1% Cu-CeO2-x@N/C cell demonstrated robust performance, achieving an initial discharge capacity of 793.2 mAh/g at 5 C over 500 cycles and maintaining a capacity of 719.9 mAh/g at 0.3 C with an electrolyte-to-sulfur ratio of 5 μL mg-1 and a high sulfur loading of 5.4 mg cm-2 after 60 cycles. These findings highlight the catalyst design for high-performance lean-electrolyte lithium-sulfur batteries, further paving the way for their commercialization.

Dual functional coordination interactions enable fast polysulfide conversion and robust interphase for high-loading lithium-sulfur batteries.

The stable operation of high-capacity lithium-sulfur batteries (LSBs) has been hampered by slow conversion kinetics of lithium polysulfides (LiPSs) and instability of the lithium metal anodes. Herein, 6-(dibutylamino)-1,3,5-triazine-2,4-thiol (DTD) is introduced as a functional additive for accelerating the kinetics of cathodic conversion and modulating the anode interface. We proposed that a coordination interaction mechanism drives the polysulfide conversion and modulates the Li+ solvated structure during the binding of the N-active site of DTD to LiPSs and lithium salts. The results show that DTD effectively promotes the redox of LiPSs and the formation of an inorganic-organic synergistic solid electrolyte interface (SEI). This suppresses the parasitic reaction of LiPSs and confers uniform lithium deposition. Therefore, the capacity decay rate per cycle of the DTD-added LSBs is only 0.066% after 600 cycles at 1C. Moreover, Li-Li symmetric batteries exhibited smaller overpotentials during long cycling and a 41% increment in cycle life. Even with high sulfur loading (5.38 mg cm-2) and a depleted electrolyte sulfur ratio (E/S = 5 μL mg-1), the capacity retention of the battery is 71.5%. This work provides a new reference for elucidating the mechanisms of polysulfide conversion and SEI interface regulation for high-energy-density lithium-sulfur batteries.

Optimizing s-p Orbital Overlap Between Sodium Polysulfides and Single-Atom Indium Catalyst for Efficient Sulfur Redox Reaction.

P-block metal carbon-supported single-atom catalysts (C-SACs) have emerged as a promising candidate for high-performance room-temperature sodium-sulfur (RT Na-S) batteries, due to their high atom utilization and unique electronic structure. However, the ambiguous electronic-level understanding of Na-dominant s-p hybridization between sodium polysulfides (NaPSs) and p-block C-SACs limits the precise control of coordination environment tuning and electro-catalytic activity manipulation. Here, s-p orbital overlap degree (OOD) between the s orbitals of Na in NaPSs and the p orbitals of p-block C-SACs is proposed as a descriptor for sulfur reduction reaction (SRR) and sulfur oxidation reaction (SOR). Compared to NG and NG-supported InN4 (NG-InN4) SACs, the nitrogen-doped graphene-supported InN5 (NG-InN5) SACs show the largest s-p OOD, demonstrating the weakest shuttle effect and the lowest reaction energy barriers in both SRR and SOR. Accordingly, the designed catalysts allow the Na-S pouch batteries to retain a high capacity of 490.7 mAh g-1 at 2 A g-1 with a Coulombic efficiency of 96 % at a low electrolyte/sulfur (E/S) ratio of 4.5 μl mg-1. This work offers an s-p orbital overlap descriptor describing the interaction between NaPSs and p-orbital-dominated catalysts for high-performance RT Na-S batteries.

A Conductive Cu-Based Metal-Organic Framework Ribbon with High-Density Redox-Active Centers as Cathode for Stable High-Capacity Lithium-Ion Batteries.

Conductive Cu-based metal-organic framework (Cu-MOF) materials hold significant potential as cathodes for lithium-ion batteries (LIBs) due to their flexible structural design, high electronic conductivity, and independence from costly resources. However, their practical application is often limited by their capacity and cyclability. In this study, we report a one-dimensional Cu-MOF (DDA-Cu, DDA=1, 5-Diamino-4, 8-dihydroxy-9, 10-anthraceneedione) featuring extended π-d conjugated coordination ribbon and high-density redox-active centers, making it a stable, high-capacity cathode for LIBs. The π-d conjugated Cu-O3N motifs embedded within the ribbon not only serve as redox-active centers for enhanced lithium-ion storage capacity but also contribute to structural robustness, enabling resistance against electrode solubility in organic electrolytes, thus ensuring superior cyclability. Furthermore, these π-d conjugated Cu-O3N units promote efficient charge transfer, leading to high electronic conductivity at room temperature. These advantageous properties allow the Cu-MOF cathode to deliver a remarkable capacity (353 mAh g-1 at 0.05 A g-1) and exceptional cyclability, achieving capacity retention of 78 % after 1000 cycles, surpassing state-of-the-art MOF electrodes. Additionally, this DDA-Cu demonstrates considerable wettability with the electrolyte, achieving outstanding performance even when tested in a lean electrolyte environment (2 μL mg-1) with a high mass loading of the MOF (6.8 mg cm-2).

Favorable Moderate Adsorption of Polysulfide on FeNi3 Intermetallic Compound Accelerating Conversion Kinetics for Advanced Lithium-Sulfur Batteries.

Sluggish conversion kinetics of polysulfides during discharge and the severe shuttle effect significantly hinder the practical application of lithium-sulfur (Li-S) batteries. In this work, the lattice engineering strategy of Fe hybridization is employed to manipulate the bulk phase spacing of FeNi3 (space group Pm3m) intermetallic compounds to adjust the 3d electronic structure, optimizing the adsorption of polysulfides, thereby accelerating the catalytic conversion. As a result, FeNi2.25@OC achieves favorable moderate adsorption toward polysulfides. Due to the larger number of electrons occupying the lowest occupied molecular orbital of Li2S4, the S-S bonds are weakened and broken. Temperature-dependent experiments confirm that FeNi2.25@OC exhibits the lowest activation energy and can effectively accelerate the catalytic conversion of polysulfides. The Li-S cell assembled with FeNi2.25@OC modified PP separator delivers a high initial discharge specific capacity of 1219.5 mAh g-1 at 0.2 C. Even at a high sulfur loading of 6.06mg cm-2 and lean electrolyte conditions (6 µL mg-1), it can cycle stably for 60 cycles.

Cationic-Dependent Cooperative Catalysis of Ni0.261Co0.739S2/N-Doped Carbon Nanotubes for Achieving Superior Electrocatalytic Activity and Cycling Stability at High Rate in Li-S Batteries

Lithium-sulfur (Li-S) batteries are increasingly recognized for their exceptional energy storage capabilities, offering an energy density of approximately 2600 Wh kg-1. This is largely attributed to the use of sulfur in the cathode—a material both abundantly available and cost-effective. However, the widespread adoption of Li-S batteries faces significant challenges, including the low electrical conductivity of sulfur and its discharge byproducts (e.g., Li2S2, Li2S), the migration of polysulfides within the electrolyte, and electrode volume expansion, which collectively impede their practical application.In the realm of recent advancements, transition metal (TM) sulfides have attracted considerable interest for their superior electrical conductivity and the presence of effective binding sites for lithium polysulfides (LiPSs), arising from a high density of valence electrons. This is a consequence of the soft basic nature of S2-/S2 2- anions, as opposed to the hard basic O2- ions. Particularly, TM sulfides with pyrite-type cubic crystalline structures, including NiS2 and CoS2, have proven to be potent electrocatalysts. They facilitate enhanced polysulfide redox reactions owing to their conductivity surpassing that of TM oxides. Furthermore, the integration of multi-cationic species into a single composite electrocatalyst has emerged as a strategic approach to refine the electronic configuration and augment the catalytic synergy of TM sulfides. Despite these developments, the discrete roles and synergistic contributions of cations within bimetallic TM sulfides remain largely unexplored, especially in comparison to the unveiled catalytic mechanisms of TM oxides.This study introduces a novel, highly active, and durable sulfur catalyst system composed of NixCo1-xS2 nanocrystals dispersed on N-doped porous carbon nanotubes (NixCo1-xS2@NPCTs). This system serves as an efficient cathode electrocatalyst for rechargeable Li-S batteries. The carbonized, porous architecture offers extensive surface area and buffering capacity for cyclic redox processes, alongside numerous chemical binding sites on the CNT framework. The ingeniously designed dual-active TM sulfides, characterized by NiOh 2+−S−CoOh 2+ bonds within the octahedral TMS6 structure, effectively catalyze sulfur cathode reactions. They fulfill multifaceted roles; specifically, CoOh 2+ sites with vacancies robustly interact with LiPSs to mitigate the shuttle effect. Concurrently, the NiOh 2+ species, with an optimal doping concentration, precisely modulate the chemical interaction with LiPSs to facilitate a sequential redox reaction, thereby promoting sustained cooperative catalysis and reducing Li2S passivation on the catalyst surface. The Ni0.261Co0.739S2 catalyst, supported by NPCT carbon, excels by achieving excellent discharge capacity and exhibiting remarkable long-term electrochemical stability. Even under harsh conditions with a low electrolyte-to-sulfur ratio (E/S = 10.0 μL mg-1), this catalyst system demonstrates superior cycling performance and durability. Notably, the Ni0.261Co0.739S2@NPCTs catalyst system showcases exceptional cyclic endurance, maintaining a capacity of 511 mAh g-1 with a mere 0.055% decay per cycle at a 5.0 C rate over 1000 cycles, alongside a significant areal capacity of 2.20 mAh cm-2 under a sulfur loading of 4.61 mg cm-2 after 200 cycles at 0.2 C. Complementary theoretical DFT calculations corroborate the experimental results, enhancing our understanding of the efficacy of the catalyst system, particularly in terms of weakend sulfur bonding strength and optimzed binding energy which are pivotal for the catalytic performance of NixCo1-xS2@NPCTs in interactions with TM sulfides and lithium polysulfides. Our findings could highlight the importance of leveraging the synergistic potential of advanced carbon hosts and optimized bimetallic sulfide electrocatalysts, while also illuminating the intricate atomic configurations crucial for augmenting the redox activity of Li-S batteries in practical applications. Figure 1

An Amphiphilic Molecule Induced Anion-Enrichment Interface for Next-Generation Lithium Metal Batteries.

The electrolyte engineering enables the fabrication of robust electrode/electrolyte interphase with excellent electrochemical stability for reliable lithium (Li) metal batteries (LMBs). Herein, an amphiphilic molecule nonafluoro-1-butanesulfonate (NFSA) is employed in electrolytes to realize anion-enrichment interfacial design. The functions of such an amphiphilic molecule in the electrolyte and anode/electrolyte interphases of LMBs are elucidated via theoretical and experimental analyses. The polar lithophilic segments (-SO3-) present a capability to solvate Li+, while the perfluoroalkyl chains (-CF2CF2CF2CF3) exhibit a solvent-phobic, which alters the Li+ solvation environment in the electrolyte and thus building a favorable interphase enriched with anion-derived inorganic compositions on Li electrode. As a result, the designed electrolyte enables stable operation of the Li||Cu cells for more than 200 cycles with a cumulative irreversible capacity loss of only 2.4 mAh cm-2, and the long-term cycle life of the Li||Li cells is extended to more than 1500h with a small overpotential (36.5mV). Moreover, prolonged cycle life of the full cell assembled with commercial LiFePO4 cathode (over 80% capacity retention after 500 cycles at 0.5 C) is achieved even under the limiting Li source (≈5 mAh cm-2), high cathode loading (≈12mg cm-2), and lean electrolyte (≈2.5µL mg-1).

Optimizing High Energy Density Sulfur Cathodes: A Multivariate Approach to Electrode Formulation and Processing

Lithium-sulfur (Li-S) batteries involve complex solid-liquid-solid phase transformations during both discharging and charging processes, where cathode materials, formulation, and structure play a crucial role. Here, a design of experiments (DoE) methodology and an empirical model are developed to systematically explore the interactions and trade-offs among cathode factors and process variables, and to obtain generalizable effects estimates for the multivariate system. Compared to the conventional one-factor-at-a-time (OFAT) approach, this work demonstrates advantages in both efficiency and accuracy by allowing the data to guide future research and decisions. An optimized cathode formulation and processing is predicted and validated experimentally, achieving over 1000 mAh g-1 in discharge capacity and improved cycling under practical lean electrolyte (4 µL mg-1 S) and high S-loading cathodes (>4 mg cm-2) conditions. The optimized cathode was scaled up and assembled into Li-S pouch cells, achieving 316 Wh kg-1 in cell level energy, proving that the comprehensive and rigorous framework for optimizing complex systems with DoE leads to improved performance in a practical pouch cell system.

Natural Polyphenol-Reinforced Ion-Selective Separators for High-Performance Lithium-Sulfur Batteries with High Sulfur Loading and Lean Electrolyte.

Ion-selective separators are promising to inhibit soluble intermediates shuttle in practical lithium-sulfur (Li-S) batteries. However, designing and fabricating such high-performance ion-selective separators using cost-effective, eco-friendly, and versatile methods remains a formidable challenge. Here we present ion-selective separators fabricated via the spontaneous deposition of green tea-derived polyphenols onto a polypropylene separator, aimed at enhancing the stability of Li-S batteries. The resulting natural polyphenol-reinforced ion-selective (NPRIS24) separators exhibit rapid Li ion transport and high soluble intermediates inhibition capability with an ultralow shuttle rate of 0.67 % for Li2S4, 0.19 % for Li2S6 and 0.10 % for Li2S8. This superior ion-selectivity arises from the high electronegativity and strong lithiophilic nature of the phenolic compounds. Consequently, we have achieved high-performance Li-S batteries that are steadily cyclable under the challenging conditions of an S loading of 5.7 mg cm-2, an electrolyte-to-S ratio of 5.1 μL mg-1, and a 50 μm Li foil anode. Furthermore, the NPRIS24 separator enhances the performance of other Li metal batteries utilizing commercial LiFePO4 (5.3 mg cm-2) and LiNi0.5Co0.2Mn0.3O2 (9.9 mg cm-2) cathodes. This work underscores the potential of utilizing natural polyphenols for the design of advanced ion-selective separators in energy storage systems.

Multifunctional Ultrathin Ti3C2Tx MXene@CuCo2O4 /PE Separator for Ultra-High-Energy-Density and Large-Capacity Lithium-Sulfur Pouch Cells.

The shuttling of lithium polysulfides (LiPSs), sluggish reaction kinetics, and uncontrolled lithium deposition/stripping remain the main challenges in lithium-sulfur batteries (LSBs), which are aggravated under practical working conditions, i.e., high sulfur loading and lean electrolyte in large-capacity pouch cells. This study introduces a Ti3C2Tx MXene@CuCo2O4 (MCC) composite on a polyethylene (PE) separator to construct an ultrathin MXene@CuCo2O4/PE (MCCP) film. The MCCP functional separator can deliver superior LiPSs adsorption/catalysis capabilities via the MCC composite and regulate the Li+ deposition through a conductive Ti3C2Tx MXene framework, enhancing redox kinetics and cycling lifetime. When paired with sulfur/carbon (S/C) cathode and lithium metal anode, the resultant 10 Ah-level pouch cell with the ultrathin MCCP separator achieves an energy density of 417Wh kg-1 based on the whole cell and a stable running of 100 cycles under practical operation conditions (cathode loading = 10.0 mg cm-2, negative/positive areal capacity ratio (N/P ratio) = 2, and electrolyte/sulfur weight ratio (E/S ratio) = 2.6 µL mg-1). Furthermore, through a systematic evaluation of the as-prepared Li-S pouch cell, the study unveils the operational and failure mechanisms of LSBs under practical conditions. The achievement of ultrahigh energy density in such a large-capacity lithium-sulfur pouch cell will accelerate the commercialization of LSBs.

Withdrawal: Steering Sulfur Reduction Pathways via Cisplatin Enables High Performance in Lithium-Sulfur Batteries.

The sulfur reduction reaction (SRR) is an attractive 16-electron transfer process that endows Li-S batteries with a theoretical capacity of 1,672 mAh g-1. However, the slow kinetics and complex pathways of the SRR cause the shuttling of soluble polysulfides (PSs), thus fast capacity fading. Here, we report using cisplatin (cis-Pt) as a novel mediator to improve the SRR kinetics and a molecular probe to identify the SRR pathways. We show that cis-Pt with a reductive Pt2+ center can directly slice the S-S bonds of PSs, leading to enhanced charge transfer kinetics, guided SRR pathways, and depth conversion of PSs to Li2S. With cis-Pt added, Li-S coin cells deliver a maximum specific capacity of 1,437 mAh g-1 and a capacity decay of 0.017% per cycle after 1000 cycles, while a pouch cell with a practical electrolyte-sulfur ratio (2.5 μl mg-1) exhibits a high energy density of 318.8 Wh kg-1. Our mechanistic studies reveal that cis-Pt steers the cathodic SRR pathways by generating redox active cis-Pt/PSs complexes, enabling the replacement of the sluggish SRR with a faster redox cycling of Pt4+/Pt2+ pairs. These findings provide insights into the rational design of functional mediators for tackling the cathodic challenges inside Li-S 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.

Nitrogen-Doped TiO2- x(B)/MXene Heterostructures for Expediting Sulfur Redox Kinetics and Suppressing Lithium Dendrites.

Practical application of lithium-sulfur (Li-S) batteries is severely impeded by the random shuttling of soluble lithium polysulfides (LiPSs), sluggish sulfur redox kinetics, and uncontrollable growth of lithium dendrites, particularly under high sulfur loading and lean electrolyte conditions. Here, nitrogen-doped bronze-phase TiO2(B) nanosheets with oxygen vacancies (OVs) grown in situ on MXenes layers (N-TiO2- x(B)-MXenes) as multifunctional interlayers are designed. The N-TiO2- x(B)-MXenes show reduced bandgap of 1.10eV and high LiPSs adsorption-conversion-nucleation-decomposition efficiency, leading to remarkably enhanced sulfur redox kinetics. Moreover, they also have lithiophilic nature that can effectively suppress dendrites growth. The cell based on the N-TiO2- x(B)-MXenes interlayer under sulfur loading of 2.5mg cm-2 delivers superior cycling performance with a high specific capacity of 690.7 mAh g-1 over 600 cycles at 1.0 C. It still has a notable areal capacity of 6.15 mAh cm-2 after 50 cycles even under a high sulfur loading of 7.2mg cm-2 and a low electrolyte-to-sulfur (E/S) ratio of 6.4 µL mg-1. The Li-symmetrical battery with the N-TiO2- x(B)-MXenes interlayer showcases a low over-potential fluctuation with 21.0mV throughout continuous lithium plating/stripping for 1000h. This work offers valuable insights into the manipulation of defects and heterostructures to achieve high-energy Li-S batteries.

Multifunctional TiN-MXene-Co@CNTs Networks as Sulfur/Lithium Host for High-Areal-Capacity Lithium-Sulfur Batteries.

The inevitable shuttling and slow redox kinetics of lithium polysulfides (LiPSs) as well as the uncontrolled growth of Li dendrites have strongly limited the practical applications of lithium-sulfur batteries (LSBs). To address these issues, we have innovatively constructed the carbon nanotubes (CNTs) encapsulated Co nanoparticles in situ grown on TiN-MXene nanosheets, denoted as TiN-MXene-Co@CNTs, which could serve simultaneously as both sulfur/Li host to kill "three birds with one stone" to (1) efficiently capture soluble LiPSs and expedite their redox conversion, (2) accelerate nucleation/decomposition of solid Li2S, and (3) induce homogeneous Li deposition. Benefiting from the synergistic effects, the TiN-MXene-Co@CNTs/S cathode with a sulfur loading of 2.5 mg cm-2 could show a high reversible specific capacity of 1129.1 mAh g-1 after 100 cycles at 0.1 C, and ultralong cycle life over 1000 cycles at 1.0 C. More importantly, it even achieves a high areal capacity of 6.3 mAh cm-2 after 50 cycles under a sulfur loading as high as 8.9 mg cm-2 and a low E/S ratio of 5.0 μL mg-1. Besides, TiN-MXene-Co@CNTs as Li host could deliver a stable Li plating/striping behavior over 1000 h.

The Impact of Oxygen Content in O-Doped MoS2 on the Kinetics of Polysulfide Conversion in Li-S Batteries.

Polysulfide shuttle and sluggish sulfur redox kinetics remain key challenges in lithium-sulfur batteries. Previous researches have shown that introducing oxygen into transition metal sulfides helps to capture polysulfides and enhance their conversion kinetics. Based on this, further investigations are conducted to explore the impact of oxygen doping levels on the physical-chemical properties and electrocatalytic performance of MoS2. The findings reveal that MoS2 doped with high-content oxygen exhibits enhanced conductivity and polysulfides conversion kinetics compared to MoS2 with low-content oxygen doping, which can be attributed to the alteration of crystal structure from 2H-phase to the 1T-phase, the introduction of increased Li-O interactions, and the effect of defects resulting from high-oxygen doping. Consequently, the lithium-sulfur batteries using high-oxygen doped MoS2 as a catalyst deliver a high discharge capacity of 1015 mAh g-1 at 0.25C and maintain 78.5% capacity after 300 more cycles. Specifically, lithium-sulfur batteries employing paper-based electrodedemonstrate an areal capacity of 3.91 mAh cm-2 at 0.15C, even with sulfur loading of 4.1mg cm-2 and electrolyte of 6.7µL mg-1. These results indicate that oxygen doping levels can modify the properties of MoS2, and high-oxygen doped MoS2 shows promise as an efficient catalyst for lithium-sulfur batteries.

Flash Joule Heating: A Promising Method for Preparing Heterostructure Catalysts to Inhibit Polysulfide Shuttling in Li-S Batteries.

The "shuttle effect" issue severely hinders the practical application of lithium-sulfur (Li-S) batteries, which is primarily caused by the significant accumulation of lithium polysulfides in the electrolyte. Designing effective catalysts is highly desired for enhancing polysulfide conversion to address the above issue. Here, the one-step flash-Joule-heating route is employed to synthesize a W-W2C heterostructure on the graphene substrate (W-W2C/G) as a catalytic interlayer for this purpose. Theoretical calculations reveal that the work function difference between W (5.08eV) and W2C (6.31eV) induces an internal electric field at the heterostructure interface, accelerating the movement of electrons and ions, thus promoting the sulfur reduction reaction (SRR) process. The high catalytic activity is also confirmed by the reduced activation energy and suppressed polysulfide shuttling by in situ Raman analyses. With the W-W2C/G interlayer, the Li-S batteries exhibit an outstanding rate performance (665 mAh g-1 at 5.0 C) and cycle steadily with a low decay rate of 0.06% over 1000 cycles at a high rate of 3.0 C. Moreover, a high areal capacity of 10.9 mAh cm-2 (1381.4 mAh g-1) is obtained with a high area sulfur loading of 7.9mg cm-2 but a low electrolyte/sulfur ratio of 9.0 µL mg-1.

Manipulating Atomic-Coupling in Dual-Cavity Boride Nanoreactor to Achieve Hierarchical Catalytic Engineering for Sulfur Cathode.

The catalytic process of Li2S formation is considered a key pathway to enhance the kinetics of lithium-sulfur batteries. Due to the system's complexity, the catalytic behavior is uncertain, posing significant challenges for predicting activity. Herein, we report a novel cascaded dual-cavity nanoreactor (NiCo-B) by controlling reaction kinetics, providing an opportunity for achieving hierarchical catalytic behavior. Through experimental and theoretical analysis, the multilevel structure can effectively suppress polysulfides dissolution and accelerate sulfur conversion. Furthermore, we differentiate the adsorption (B-S) and catalytic effect (Co-S) in NiCo-B, avoiding catalyst deactivation caused by excessive adsorption. As a result, the as-prepared battery displays high reversible capacity, even with sulfur loading of 13.2 mg cm-2 (E/S=4 μl mg-1), the areal capacity can reach 18.7 mAh cm-2.

Mirror Plane Effect of Magnetoplumbite-Type Oxide Restraining Long-Chain Polysulfides Disproportionation for High Loading Lithium Sulfur Batteries.

A facile solid-state approach is employed to synthesize a novel magnetoplumbite-type oxide of NdMgAl11O19, which integrates spinel-stacking layers (MgAl2O4) with Nd-O6 mirror plane structures. The resulting NdMgAl11O19 exhibits remarkable catalytic activity and conversion efficiency during the sulfur reduction reaction (SRR) in lithium-sulfur batteries. By employing the 2D projection mapping technique of in situ confocal Raman spectroscopy and electrochemical technique, it is discovered that the exposed mirror plane structure of Nd-O6 can effectively suppress the undesiring disproportionation reaction (S8 2-→S6 2-+1/4 S8) of long-chain lithium polysulfides at the initial stages of sulfur reduction, thereby promoting the positive process of sulfur to lithium sulfide. This not only mitigates the issue of sulfur shuttle loss but also significantly improve the kinetics of the conversion process. Leveraging these advantages, the NdMgAl11O19/S cathode delivered an impressive initial capacity of up to 1398 mAh g-1 at an electrolyte/sulfur (E/S) ratio of 5.1µL mg-1 and a sulfur loading of 2.3mg cm-2. Even when the sulfur loading is increased to 10.02mg cm-2, the cathode retained a reversible areal capacity of 10.01 mAh cm-2 after 200 cycles. This mirror engineering strategy provides valuable and universal insights into enhancing the efficiency of cathodes in Li-S battery.

Quasi-Solid-State Electrolyte Induced by Metallic MoS2 for Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are a promising high-energy-density technology for next-generation energy storage but suffer from an inadequate lifespan. The poor cycle life of Li-S batteries stems from their commonly adopted catholyte-mediated operating mechanism, where the shuttling of dissolved polysulfides results in active material loss on the sulfur cathode and surface corrosion on the lithium anode. Here, we report in situ formation of a quasi-solid-state electrolyte (QSSE) on the metallic 1T phase molybdenum disulfide (MoS2) host that extends the lifetime of Li-S batteries. We find that the metallic 1T phase MoS2 host is able to initiate the ring-opening polymerization of 1,3-dioxolane (DOL), forming an integrated QSSE inside batteries. Nuclear magnetic resonance analysis reveals that the QSSE consists of ∼13% liquid DOL in a solid polymer matrix. The QSSE efficiently mediates sulfur redox reactions through dissolution-conversion chemistry while simultaneously suppressing polysulfide shuttling. Therefore, while ensuring high sulfur utilization, it avoids degradation of both electrodes, as well as the concomitant electrolyte consumption, leading to enhanced cycling stability. Under a practical lean electrolyte condition (electrolyte-to-sulfur ratio = 2 μL mg-1), Li-S pouch cell batteries with the QSSE demonstrate a capacity retention of 80.7% after 200 cycles, much superior to conventional liquid electrolyte cells that fail within 70 cycles. The QSSE also enables Li-S pouch cell batteries to operate across a wider temperature range (5 to 45 °C), together with improved safety under mechanical damage.

Catalytic decomposition of ethylene carbonate by pyrrolic-N to stabilize solid electrolyte interphase on graphite anode under extreme conditions

Despite the dominated anode materials of graphite for lithium-ion batteries (LIBs), the poor rate capability and inferior cyclability restain their applications under extreme conditions due to their deficient interfacial chemistry. Herein, an ultrathin but Li2CO3-rich solid electrolyte interphase (SEI) is manipulated by the decomposition of ethylene carbonate (EC) on graphite anode with nitrogenous amorphous carbon coating (denoted as GMIB-2P). Specifically, Li2CO3 can enable a decreased charge transfer resistance and faster Li+ diffusion capability. In addition, we demonstrate the catalytic effect of pyrrolic-N on graphite surface with prominent wettability induces the rapid decomposition of EC with low reaction energy barrier through density function theory (DFT) calculation. Consequently, GMIB-2P delivers an outstanding capacity retention ratio of 90.82% after 300 cycles at 1 C and an improved initial Coulombic efficiency (ICE, 90.77% vs. 85.35%). More importantly, GMIB-2P possesses durable-cycling capability even with lean electrolytes of 5 μL mg-1 and as well as 85.68% capacity retention for over 300 cycles at 60 ℃. Our work highlights the key role of EC in tailoring interfacial chemistry from structure regulations and provides new guidelines to design more reliable anodes for LIBs under extreme conditions.