High-performance Li-S Batteries Research Articles

Cyclodextrin Metal-Organic Framework Functionalized Carbon Materials with Optimized Interface Electronics and Selective Supramolecular Channels for High-Performance Lithium-Sulfur Batteries.

During the reaction process in lithium-sulfur batteries, Lewis acidic lithium polysulfides (LiPSs) affect ion distribution and overall electrolyte stability, degrading battery performance and product distribution (e.g., Li2S). Here, a microenvironment regulation strategy with optimized interface electronics and selective supramolecular channels, is proposed to enhance LiPS reaction kinetics through Lewis basic γ-cyclodextrin metal-organic framework (γ-CDMOF). To validate this concept, γ-CDMOF is rapidly synthesized on 3D graphene foam (GF) via a microwave-assisted method, resulting in a γ-CDMOF/GF cathode for high-performance Li-S batteries. A range of analytical techniques combined with density functional theory (DFT) calculations confirm that introducing a Lewis basic supramolecular microenvironment mitigates the LiPSs shuttle effect, enhances polysulfide capture, and improves sulfur redox conversion. Additionally, COMSOL simulations reveal that the γ-CDMOF framework and oxygen sites significantly reduce volumetric expansion stress during the LiPS solid-liquid phase transition. Impressively, the γ-CDMOF/GF cathode exhibits exceptional performance, including a high specific capacity (1253.01 mAh g⁻¹ at 0.1C), excellent rate performance (589.68 mAh g⁻¹ at 5C), and long cycle life (over 1200 cycles). This study introduces a new concept of supramolecular microenvironment regulation and interfacial interaction strategy, offering a unique approach for the development of multifunctional electrode materials.

In Situ Synthesis of CoMoO4 Microsphere@rGO as a Matrix for High-Performance Li-S Batteries at Room and Low Temperatures.

Lithium-sulfur batteries (Li-S batteries) have attracted wide attention due to their high theoretical energy density and the low cost of sulfur cathode material. However, the poor conductivity of the sulfur cathode, the polysulfide shuttle effect, and the slow redox kinetics severely affect their cycling performance and Coulombic efficiencies, especially under low-temperature conditions, where these effects are more exacerbated. To address these issues, this study designs and synthesizes a microspherical cobalt molybdate@reduced graphene oxide (CoMoO4@rGO) composite material as the cathode material for Li-S batteries. By growing CoMoO4 nanoparticles on the rGO surface, the composite material not only provides a good conductive network but also significantly enhances the adsorption capacity to polysulfides, effectively suppressing the shuttle effect. After 100 cycles at room temperature with a current density of 1 C, the reversible specific capacity of the battery stabilizes at 805 mAh g-1. Notably, at -20 °C, the S/CoMoO4@rGO composite achieves a reversible specific capacity of 840 mAh g-1. This study demonstrates that the CoMoO4@rGO composite has significant advantages in suppressing polysulfide diffusion and expanding the working temperature range of Li-S batteries, showing great potential for applications in next-generation high-performance Li-S batteries.

Heterostructure Mo2C/α-MoO3/G catalyst based heterogeneous catalysis/deposition mechanism for high-performance Li-S battery

Lithium-sulfur batteries (LSBs) have been recognized as a promising energy device due to their outstanding theoretical energy density and abundant resources. However, the commercial application remains obstruction by the sluggish redox kinetics and serious shuttle effect of polysulfides. Herein, a heterostructural Mo2C/α-MoO3/graphene (Mo2C/α-MoO3/G) catalyst based on a heterogeneous catalysis/deposition mechanism is proposed to address these issues. The prepared Mo2C/α-MoO3/G catalyst is feature with high-activity facet, fast electron delocalization and build-in electric field, which drastically promotes the redox kinetics of polysulfides on the surface of crystal phase. Simultaneously, the heterostructural Mo2C/α-MoO3/G catalyst is capable of capturing polysulfides effectively and eliciting the heterogeneous deposition of Li2S on the surface of amorphous phase, of which guarantee the efficient catalytic characteristic during the charge/discharge processes. In addition, the shuttle effect is restricted with a lower shuttle factor (∼0.02). Therefore, the assembled LSBs based Mo2C/α-MoO3/G catalyst modifying separator exhibits an impressive specific capacity of 1311.4 mAh g−1 at 0.2 C and excellent rate capability of 580.3 mAh g−1 at 4 C. More importantly, it demonstrated satisfied cycling stability even at a high sulfur loading mass (4.2 mgS cm−2) and lean electrolyte conditions (9.3 μL gS-1). This work reveals a novel paradigm for optimizing the kinetics behaviors to achieve the commercialization of LSBs.

Synergistic promotion of reaction kinetics for LiPSs at high loadings by interfacial built-in electric field and sulfur vacancies of ternary heterostructure for high-performance Li-S batteries

The practical application of lithium-sulfur batteries is significantly impeded by the chaotic migration of lithium polysulfides, sluggish redox-reaction kinetics, and pronounced shuttle effect. Herein, a ternary heterostructure (MoS2-x/MoO2/CoP) is developed with a spontaneous built-in electric field (BIEF) and enriched sulfur vacancies. This heterostructure comprises MoS2-x, which has a high adsorption capability and work function; CoP, noted for its low work function and potent catalytic properties; and MoO2, which features a work function between that of MoS2-x and CoP and serves as a bridge with excellent electronic conductivity. An appropriate combination of the catalyst and adsorbent with sulfur vacancies controls the direction of the BIEF, realizing the “adsorption-directed migration-catalytic” reaction mechanism for sulfur species. Specifically, the synergetic effect of the BIEF and sulfur vacancies enhances electron migration from CoP to MoS2-x, which improves the lithium polysulfide (LiPSs) trapping and accelerates the directional migration of LiPSs to CoP, thereby enabling the efficient catalytic conversion of sulfur species. Consequently, batteries equipped with MoS2-x/MoO2/CoP interlayers that contain sulfur vacancies demonstrate an ultrahigh initial specific capacity of 1356.2 mA h g−1 at 0.2 C, maintaining a capacity of 708.3 mAh g−1 after 1000 cycles at 2 C. Even with sulfur loading increased to 7.13 mg cm−2, these batteries display an initial specific capacity of 7.2 mAh cm−2. This work provides a feasible approach for the rational design of vacancy-containing ternary heterostructure catalysts for commercial lithium-sulfur batteries.

Separator modification with a high-entropy hydroxyphosphate, Co0.29Ni0.15Fe0.33Cu0.16Ca3.9(PO4)3(OH), for high-performance Li-S batteries

The shuttle effect of lithium polysulfides (LiPSs) significantly hinders the practical application of lithium-sulfur batteries (LSBs). Herein, a high-entropy hydroxyphosphate (Co0.29Ni0.15Fe0.33Cu0.16Ca3.9(PO4)3(OH), denoted as HE-CHP), was synthesized by metal cation exchange with calcium hydroxyphosphate (CHP) and then coated on polypropylene (PP) separators to suppress the shuttling of LiPSs. Density functional theory calculations indicated that the various introduced metal cations could effectively modulate the binding strength of soluble polysulfides and enhance the reaction kinetics of LiPSs conversion. As a result, LSBs using the HE-CHP@PP separator exhibited an excellent discharge capacity (1297 mAh g−1 under 0.2 C) and a slow capacity decay during long-term cycling (0.046 % per cycle at 2 C). At a sulfur loading of up to 6.5 mg cm−2, the LSB with HE-CHP@PP separator displayed a discharge capacity of 5.8 mAh cm−2. Notably, the CNT@S||Li Li-S pouch cell with HE-CHP modified separator delivered an initial energy density of 432 Wh kg−1.

Dry carbothermal reaction-enabled ultra-dense nanoparticle coatings for high-performance Li-S batteries

Electrocatalysts are crucial for facilitating the sluggish conversion between S and sulfide in Li-S batteries. Despite recent exploration of advanced materials, there remains a significant gap in the morphology design rationale oriented towards practical operation conditions. In this study, we introduce a dry process based on the carbothermal reaction of oxides to achieve nanoparticle (NP) electrocatalyst coatings. This process enables us to produce ultra-high-density NPs with several tens of particles per 100 nm x 100 nm area. We unveil that this high coating density boosts the conversion kinetics by dominating a solution-phase disproportionation reaction, thereby promoting the growth of non-passivating particulate sulfide. With this NP-coated cathode, we achieve excellent kinetic performance, maintaining 53 % of cell capacity retention even with a 50-fold increase in C-rate, and exhibiting only a 0.04 % capacity decay per cycle over 300 cycles at 10C. Remarkably, our cathode achieves an initial areal capacity of 7.51 mAh cm−2 in a full cell, significantly outperforming cells reported in previous studies as well as conventional Li-ion batteries.

Heteroelectrocatalyst MoS2@CoS2 modified separator for Li-S battery: Unveiling superior polysulfides conversion and reaction kinetics

Mitigating the shuttle effect of polysulfides and enhancing their conversion efficiency are critical challenges for the practical application of Li-S batteries. Herein, we present a novel MoS2@CoS2 heteroelectrocatalyst synthesized via a hydrothermal method, used to modify the separator for Li-S batteries. This innovative heterostructure combines the exceptional properties of metallic CoS2 and semiconductor MoS2, creating a synergistic effect that significantly improves electrochemical performance. The built-in electric field at the heterointerface promotes rapid charge transport and enhances surface reaction kinetics, effectively addressing polysulfide shuttle and sluggish redox kinetics. The Li-S battery with MoS2@CoS2 separator exhibits an impressive initial capacity of 1480 mAh g−1 at 0.1 C and maintains 811 mAh g−1 at 3 C, with long-term cycling stability showing a minimal decay rate of 0.05 % per cycle at 1 C. Even with high sulfur loading (6 mg cm−2) and a low electrolyte/sulfur ratio, the cell achieves a high reversible capacity of 4.5 mAh cm−2 at 0.2 C. The innovative approach of integrating semimetal-semiconductor heterointerfaces opens new avenues for the development of high-performance Li-S batteries, addressing critical challenges and paving the way for future technological advancements in the field.

Titanium-containing high entropy oxide (Ti-HEO): A redox expediting electrocatalyst towards lithium polysulfides for high performance Li-S batteries

Titanium-containing high entropy oxide (Ti-HEO): A redox expediting electrocatalyst towards lithium polysulfides for high performance Li-S batteries

The “d-p orbital hybridization”-guided design of novel two-dimensional MOFs with high anchoring and catalytic capacities in Lithium − Sulfur batteries

The energy system of lithium-sulfur batteries is quite promising, however, lithium-sulfur batteries still suffer from considerable problems, such as the abominable shuttle effect of polysulfides (LiPSs), the low conductivity of the solid-phase products, the slow redox kinetics during charging and discharging, and the volume expansion. Herein, the hybridization pattern between the d-orbitals of various transition metal atoms and the p-orbitals of sulfides is revealed grounded in the theory of density function, which explains the high adsorption strength of two-dimensional metal–organic frameworks (MOFs) with LiPSs and accelerates the screening of high-performance anchoring and catalytic materials. The results elucidate that the coordinated transition metal–organic frameworks (Mo-NH MOF) monolayers increase the capacity of LiPSs to anchor by forming more π-bonds from the hybridization of the S p orbitals and Mo d orbitals. Notably, Mo-NH MOF exhibits bifunctional catalytic activity for sulfur reduction as well as Li2S decomposition reactions during charging and discharging, which improves the conversion efficiency of redox reactions. As a result, new MOF materials featuring unique active centers and the potential mechanism by which the active centers modulate the performance of the substrate materials are revealed, and this finding may accelerate the development of high-performance Li-S batteries.

Sulfonic group modifying cobalt (II) phthalocyanine molecule to boost the polysulfide reaction kinetic for high-performance lithium sulfur battery

Metal phthalocyanine have been regarded as an effective additive to restrain the LiPS diffusion process in sulfur cathode to achieve high-performance Li-S battery. Herein, molecular engineering has been used to boost the LiPS adsorption and catalysis abilities of metal phthalocyanine distinctly through a simple sulfonic group grafting strategy. The derived CNT/s-CoPc/S cathode could deliver the initial discharge capacity of 679.8 mAh/g at 1.0 C and no obvious capacity fading even after 500 cycles. The satisfactory electrochemical performance indicates the promising application of CNT/s-CoPc composite as an efficient sulfur carrier. The research presents a successful modification method for the improvement of metal phthalocyanine based additive, contributing to their advancements in Li-S battery furtherly.

Mo3P/Mo heterojunction for efficient conversion of lithium polysulfides in high-performance lithium-sulfur batteries.

Realizing efficient immobilization of lithium polysulfides (LiPSs) as well as reversible catalytic conversion between LiPSs and the insoluble Li2S is vital to restrain the shuttle effect, which requires highly reactive catalysts for high-performance Li-S batteries. Here, three-dimensional ordered porous Mo-based metal phosphides (3DOP Mo3P/Mo) with heterogeneous structures were fabricated and utilized as separator-modified coatings for Li-S batteries to catalyze the conversion of LiPSs. The adsorption, catalytic and electrochemical performance of the corresponding cells were compared among 3DOP Mo3P/Mo and 3DOP Mo, by kinetic and electrochemical performance measurements. It was found that the cell with 3DOP Mo3P/Mo modified separator deliver better electrochemical performance, with a high specific capacity of 469.66mAh g-1 after 500 cycles at a high current density of 1°C. This work provides an idea and a guideline for the design of the separator modification for high-performance Li-S batteries.

Fe3O4-doped mesoporous carbon cathode with a plumber’s nightmare structure for high-performance Li-S batteries

Shuttling of lithium polysulfides and slow redox kinetics seriously limit the rate and cycling performance of lithium-sulfur batteries. In this study, Fe3O4-dopped carbon cubosomes with a plumber’s nightmare structure (SP-Fe3O4-C) are prepared as sulfur hosts to construct cathodes with high rate capability and long cycling life for Li-S batteries. Their three-dimensional continuous mesochannels and carbon frameworks, along with the uniformly distributed Fe3O4 particles, enable smooth mass/electron transport, strong polysulfides capture capability, and fast catalytic conversion of the sulfur species. Impressively, the SP-Fe3O4-C cathode exhibits top-level comprehensive performance, with high specific capacity (1303.4 mAh g−1 at 0.2 C), high rate capability (691.8 mAh gFe3O41 at 5 C), and long cycling life (over 1200 cycles). This study demonstrates a unique structure for high-performance Li-S batteries and opens a distinctive avenue for developing multifunctional electrode materials for next-generation energy storage devices.

Synergistic engineering of structural and electronic regulation in necklace-like UiO-66/ACNT structure toward lithium-sulfur batteries with fast polysulfide redox

Although UiO-66-based metal-organic framework (MOF) composites have been widely applied in the entrapment and catalytic effect toward lithium polysulfides (LiPSs), the synergistic engineering of structural and electronic regulation strategy has not been carefully considered. Herein, we optimize the internal cluster structure, rational regulate the size of UiO-66, and design the necklace-like structure composed of UiO-66 nanoparticles and acid-treated carbon nanotube (UiO-66/ACNT) through simple hydrothermal reaction and thermal treatment strategy. According to experiments and density universal function theory calculations, the improved UiO-66/ACNT architecture effectively provides more polarity to capture polysulfides via exposing more active sites and effectively delivers electrocatalytic activity of polysulfide conversion. Furthermore, systematic electrocatalytic kinetics, in situ Raman spectroscopy and in-situ impedance analysis indicate the functional separator can inhibit the shuttling effect, and catalyze the conversion of lithium polysulfide. As a result, Li-S batteries with functional separators exhibit excellent electrochemical performance (low fading rate over 1000 cycles of 0.06 % per cycle at 1C, high areal capacity of 4.01 mAh cm−2 at 0.2C). This work offers insight into the rational design of UiO-66-based metal-organic frameworks (MOFs) through synergistic engineering for high-performance Li-S batteries.

Design of Defect-Rich MgCo-Layered Double Hydroxide Microspheres as Highly Effective Sulfur Reduction Reaction Electrocatalyst for High-Performance Li-S Batteries

Design of Defect-Rich MgCo-Layered Double Hydroxide Microspheres as Highly Effective Sulfur Reduction Reaction Electrocatalyst for High-Performance Li-S Batteries

Design of Defect-Rich MgCo-Layered Double Hydroxide Microspheres as Highly Effective Sulfur Reduction Reaction Electrocatalyst for High-Performance Li-S Batteries

Design of Defect-Rich MgCo-Layered Double Hydroxide Microspheres as Highly Effective Sulfur Reduction Reaction Electrocatalyst for High-Performance Li-S Batteries

Reviewing metal fluorides as the cathode materials for high performance Li batteries

AbstractExploring high‐energy density rechargeable lithium (Li) batteries is urgently needed to meet the demand of the large‐scale electric vehicle market. Conversion‐type metal fluorides (MFx) have been considered as desirable cathode materials for next‐generation rechargeable batteries because of their high operational voltages, environmental non‐toxicity, low cost, and high thermal stability. In this review, we present the most promising and feasible MFx applied in rechargeable Li batteries in terms of capacity, discharge potential, volume change, fabricated methods, crystal structure, and cost/abundance. The electrochemical performance is briefly illustrated, and the recent advances in mechanisms focused on MFx cathodes upon cyclic processes are noted and discussed in detail. Finally, prospects for the current challenges and possible research directions, with the aim to provide some inspiration for the development of MFx‐based cathodes are presented.

Encapsulating Sulfur into a Gel-Derived Nitrogen-Doped Mesoporous and Microporous Carbon Sponge for High-Performance Lithium-Sulfur Batteries.

The practical application of Li-S batteries (LSBs) has long been impeded by the inefficient utilization of sulfur and slow kinetics. Utilizing conductive carbonaceous frameworks as a host scaffold presents an efficient and cost-effective approach to enhance sulfur utilization for redox reactions in LSBs. However, the interaction of pure carbon materials with lithium polysulfide intermediates (LiPSs) is limited to weak van der Waals forces. Hence, the development of an economical method for synthesizing heteroatom-doped carbon materials for sulfur fixation is of paramount importance. In this study, we introduce a hierarchical porous nitrogen-doped carbon sponge (NPCS) with an exceptionally high BET surface area of 3182.2 m2 g-1, achieved through a facile template-assisted polymerization method. The incorporation of inorganic salts, free radical polymerization, and deuteric freeze-drying techniques facilitates the formation of hierarchical pores within the NPCS. After sulfur fixation, the resulting S/NPCS electrode demonstrates remarkable electrochemical performance in LSBs. Specifically, it achieves an 80% sulfur utilization rate, maintains a high reversible specific capacity of 400 mA h g-1 even after 600 cycles at a demanding current density of 5.0 A g-1, and exhibits superior rate capability. It is believed that this work will inspire the rational design of cost-effective carbon-based electrodes for high-performance LSBs.

Kinetic Promoters for Sulfur Cathodes in Lithium-Sulfur Batteries.

ConspectusLithium-sulfur (Li-S) batteries have attracted worldwide attention as promising next-generation rechargeable batteries due to their high theoretical energy density of 2600 Wh kg-1. The actual energy density of Li-S batteries at the pouch cell level has significantly exceeded that of state-of-the-art Li-ion batteries. However, the overall performances of Li-S batteries under practical working conditions are limited by the sluggish conversion kinetics of the sulfur cathodes. To overcome the above challenge, various kinetic promotion strategies have been proposed to accelerate the multiphase and multi-electron cathodic redox reactions between sulfur, lithium polysulfides (LiPSs), and lithium sulfide. Nowadays, kinetic promoters have been massively employed in sulfur cathodes to achieve Li-S batteries with high energy densities, high rates, and long lifespans. A comprehensive and timely summary of cutting-edge kinetic promoters for sulfur cathodes is of great essence to afford an in-depth understanding of the unique Li-S electrochemistry.In this Account, we outline the recent efforts on the design of sulfur cathode kinetic promoters for advanced Li-S batteries. The latest progress is discussed in detail regarding heterogeneous, homogeneous, and semi-immobilized kinetic promoters. Heterogeneous promoters, representatively known as electrocatalysts, function mainly by reducing the energy barriers of the interfacial electrochemical reactions. The working mechanism, activity regulation strategies, and reconstitution/deactivation processes of the heterogeneous promoters are reviewed to provide guiding principles for rational design. In comparison, homogeneous promoters are able to fully contact with the reaction interfaces and regulate the electron/ion-inaccessible reactants in working Li-S batteries. Redox mediators and redox comediators are typical homogeneous promoters. The former establishes extra chemical reaction pathways to circumvent the originally sluggish steps and boost the overall kinetics, while the latter fundamentally modifies the LiPS molecules to enhance their redox kinetics. For semi-immobilized promoters, the active units are generally anchored on the cathode substrate through flexible chains with mobile characteristics. Such a design endows the promoter with both heterogeneous and homogeneous characteristics to comprehensively regulate the multiphase sulfur redox reactions involving both mobile and immobile reactants.Overall, this Account summarizes the fundamental electrochemistry, design principles, and practical promotion effects of the various kinetic promoters used for the sulfur cathodes in Li-S batteries. We believe that this Account will provide an in-depth and cutting-edge understanding of the unique sulfur electrochemistry, thereby providing guidance for further development of high-performance Li-S batteries and analogous rechargeable battery systems.

Quantum Spin Exchange Interactions to Accelerate the Redox Kinetics in Li–S Batteries

HighlightsCompared with the traditional single-atom catalysts (SACs), the Mg SACs with axial displacement is accurately fabricated on the functional carbon nanotubes.The electronic spin polarization modulates the spin density of MgPc, facilitating the LiPSs conversion kinetics in Li-S batteries.The MgPc@FCNT achieves ultra-low capacity decay rate under the high sulfur loading.

Structure-defined viologen-polyoxometalate modified separator dominating endurable Li-S batteries by a synergistic adsorption-electrocatalysis mechanism

The crystalline materials can provide atomically accurate model for comprehending the structure-property-function relationships, which would be an innovative strategy to address the inherent issues in Li-S batteries. Herein, we synthesize a new crystalline compound of (HAV)[PMo12O40]·6H2O (marked as {AV-PMo12}) using Keggin-type H3PMo12O40·3H2O (PMo12) and aminopropyl viologen (AV) as precursors, which are connected by intermolecular hydrogen bonding and electrostatic attraction. When {AV-PMo12} is utilized as a modified material for separator, PMo12captures lithium polysulfides (LiPSs) by forming Li–O bonds and AV interacts with polysulfides via electrostatic attraction. More significantly, based on the precise and stable structure of {AV-PMo12}, this work innovatively utilizes in-situ Raman spectra and ex-situ XPS to intuitively reveal the catalytic mechanism of {AV-PMo12}. Specifically, {AV-PMo12} possesses bidirectional catalytic activity during charge-discharge cycles, accompanied by the stable conversion between reduced and oxidized states of PMo12. AV preferentially captures electrons and transfers them to PMo12 through hydrogen bond, which improves electron-obtaining ability of PMo12, thus promoting the catalytic activity of PMo12 for LiPSs conversion. PMo12 facilitates the desolvation process of Li+, which accelerates high-flux lithium ion diffusion and achieves uniform lithium deposition. As expected, Li-S cell using {AV-PMo12} modified separator achieves decent reversibility of 469 mAh g−1 at 2.0C after 1000 cycles and the degradation rate is only 0.034 % per cycle at 5.0C upon 1000 cycles. Meanwhile, it achieves a high capacity of 550 mAh g−1 after 200 cycles at 0.2C under a sulfur loading of 5.1 mg cm−2 with a low electrolyte/sulfur ratio of 5 μL mg−1. This work offers a comprehensive analysis of catalytic mechanism of viologen-polyoxometalate based functional material at the molecular level to boost the high-performance Li-S batteries.