Lithium Sulfur Research Articles

Recent progress and strategies of cathodes toward polysulfides shuttle restriction for lithium-sulfur batteries

Recent progress and strategies of cathodes toward polysulfides shuttle restriction for lithium-sulfur batteries

Cellulose Fiber based self-supporting paper cathode with multi-scale network structure for high performance lithium-sulfur battery

Lithium-sulfur batteries (LSBs) are gaining attention as a potential energy storage option due to their impressive theoretical specific capacity. However, the main challenges hindering its implementation include the expansion in volume of sulfur and lithium sulfide during the conversion process of charge-discharge, the limited conductivity of the active material, and specifically, the phenomenon known as shuttle effect caused by lithium polysulfides (LiPSs). The development of high-performance LSBs have led to the need for self-supporting cathode materials that can efficiently accommodate volume expansion, build up efficient conductive pathways, and suppress shuttle effects. The poly(3,4-ethylenedioxythiophene) (PEDOT) was synthesized in situ on cellulose nanofibers (CNFs), resulting in the formation of CNF@PEDOT. Subsequently, CNF@PEDOT was combined with plant fibers (PFs) and multi-wall carbon nanotubes (MWCNTs) to fabricate a self-supporting cathode featuring a multi-scale network structure denoted as CNF@PEDOT/MWCNT/PF/S. The PFs serve as the primary backbone network, CNF@PEDOT to form the secondary conductive network, and MWCNTs act as tertiary conducting networks. In fact, the design of multi-level conductive network effectively improves the conductivity of the material, and PEDOT can further adsorb and catalyze LiPSs. The incorporation of PFs significantly enhanced the mechanical robustness of the cathode and augmented its electrolyte permeability. The self-supporting CNF@PEDOT/MWCNT/PF/S cathode exhibits an initial capacity of 1204.6 mA h g−1 when loaded with 2.4 mg cm−2 of sulfur at a rate of 0.2 C. Notably, it maintains an initial discharge specific capacity of 712.9 mA h g−1 even when the sulfur load is increased to 4.3 mg cm−2. This study presents a comprehensive framework for the development of self-supporting cathodes in LSBs.

Versatile separators toward advanced lithium-sulfur batteries: status, recent progress, challenges and perspective.

Lithium-sulfur batteries (LSBs) have recently gained extensive attention due to their high energy density, low cost, and environmental friendliness. However, serious shuttle effect and uncontrolled growth of lithium dendrites restrict them from further commercial applications. As "the third electrode", functional separators are of equal significance as both anodes and cathodes in LSBs. The challenges mentioned above are effectively addressed with rational design and optimization in separators, thereby enhancing their reversible capacities and cycle stability. The review discusses the status/operation mechanism of functional separators, then primarily focuses on recent research progress in versatile separators with purposeful modifications for LSBs, and summarizes the methods and characteristics of separator modification, including heterojunction engineering, single atoms, quantum dots, and defect engineering. From the perspective of the anodes, distinct methods to inhibit the growth of lithium dendrites by modifying the separator are discussed. Modifying the separators with flame retardant materials or choosing a solid electrolyte is expected to improve the safety of LSBs. Besides, in-situ techniques and theoretical simulation calculations are proposed to advance LSBs. Finally, future challenges and prospects of separator modifications for next-generation LSBs are highlighted. We believe that the review will be enormously essential to the practical development of advanced LSBs.

Amorphous MoS2/MoO3 nanosheets as high‐efficient polysulfide barrier in Li‐S batteries

Lithium‐sulfur batteries (LSBs) are seriously impeded by poor reaction kinetics and the polysulfides shuttling, leading to low utilization of sulfur and poor cycling performance. Herein, amorphous MoS2/MoO3 nanosheets are prepared by a one‐step formamide (FA)‐assisted strategy. Due to the merits of high adsorption capability and good catalytic activity of MoS2, relatively high electronic conductivity and strong polarity of MoO3, and abundant active sites of amorphous nanosheet structure, the LSBs based on amorphous MoS2/MoO3‐2 nanosheets coated separator exhibit an outstanding specific capacity (1420.2 mA h g‐1 at 0.1 C), excellent rate capacity (505.4 mA h g‐1 at 5 C), and long cycle life (a negligible decay rate of 0.063 % per cycle at 0.5 C). This work provides an idea for designing efficient amorphous catalytic materials in LSBs.

Fabrication of Fe/KB composite as sulfur host for Li-S battery.

Lithium sulfur battery is a novel kind of secondary battery which has high energy density, however its application is greatly affected by the shuttle effect of polysulfides generated in the redox reaction of cathode electrode. Metal active sites are supposed as effective catalysts which can absorb and accelerate the conversion efficiency oflithium polysulfides, thus the shuttle effect will be alleviated. In this work, we conducted a simple way to prepare a metal Fe doped ketjen black to serve as the sulfur host of lithium sulfur battery. Ketjen black has a large specific surface area and rich porous structure, while Fe nanodot is an excellent catalyst for lithium polysulfides. Because of these advantages, the Fe/KB host can effectively confine a large amount of active material and accelerate its, therefore the Fe/KB-S cathode electrode show an excellent electrochemical performance.

Construction and catalysis role of a kinetic promoter based on lithium-insertion technology and proton exchange strategy for lithium-sulfur batteries

The high theoretical energy density and specific capacity of lithium-sulfur (Li-S) batteries have garnered considerable attention in the prospective market. However, ongoing research on Li-S batteries appears to have encountered a bottleneck, with unresolved key technical challenges such as the significant shuttle effect and sluggish reaction kinetics. This investigation explores the catalytic efficacy of three catalysts for Li-S batteries and elucidates the correlation between their structure and catalytic impacts. The results suggest that the combined utilization of lithium-insertion technology and a proton exchange approach for δ-MnO2 can optimize its electronic structure, resulting in an optimal catalyst (H/Li inserted δ-MnO2, denoted as HLM) for the sulfur reduction reaction. The replacement of Mn sites in δ-MnO2 with Li atoms can enhance the structural stability of the catalyst, while the introduction of H atoms between transition metal layers contributes to the satisfactory catalytic performance of HLM. Theoretical calculations demonstrate that the bond length of Li2S4 adsorbed by the HLM molecule is elongated, thereby facilitating the dissociation process of Li2S4 and enhancing the reaction kinetics in Li-S batteries. Consequently, the Li-S battery utilizing HLM as a catalyst achieves a high areal specific capacity of 4.2 mAh cm−2 with a sulfur loading of 4.1 mg cm−2 and a low electrolyte/sulfur (E/S) ratio of 8 μL mg−1. This study introduces a methodology for designing effective catalysts that could significantly advance practical developments in Li-S battery technology.

Rare Earth Single-Atom Catalysis for High-Performance Li-S Full Battery with Ultrahigh Capacity.

Lithium-sulfur (Li-S) batteries have many advantages but still face problems such as retarded polysulfides redox kinetics and Li dendrite growth. Most reported single atom catalysts (SACs) for Li-S batteries are based on d-band transition metals whose d orbital constitutes active valence band, which is inclined to occur catalyst passivation. SACs based on 4f inner valence orbital of rare earth metals are challenging for their great difficulty to be activated. In this work, we design and synthesize the first rare earth metal Sm SACs which has electron-rich 4f inner orbital to promote catalytic conversion of polysulfides and uniform deposition of Li. Sm SACs enhance the catalysis by the activated 4f orbital through an f-d-p orbital hybridization. Using Sm-N3C3 modified separators, the half cells deliver a high capacity over 600 mAh g-1 and a retention rate of 84.3% after 2000 cycles. The fabricated S/CNTs|Sm-N3C3@PP|Sm-N3C3-Li full batteries can provide an ultra-stable cycling performance of a retention rate of 80.6% at 0.2 C after 100 cycles, one of the best full Li-S batteries. This work provides a new perspective for the development of rare earth metal single atom catalysis in electrochemical reactions of Li-S batteries and other electrochemical systems for next-generation energy storage.

Hierarchical Co-doped hollow Ti3C2Tx tubes with built-in electron/ion transport network for high-performance lithium sulfur batteries

A crucial approach to enhancing the electrochemical performance of lithium-sulfur batteries (LSBs) is to develop a dependable sulfur host material possessing reasonable structure, high electrical conductivity, and exceptional adsorption/catalytic capabilities towards lithium polysulfides (LiPSs). Herein, Co-doped hollow Ti3C2Tx tubes with in-situ grown CNTs as a built-in electron/ion transport network (HTCTs/Co/CNTs) are prepared via electrospinning technique combined with the self-catalyzed growth strategy. The unique hierarchical porous structure of HTCTs/Co/CNTs not only increases the sulfur loading and alleviates the volume expansion, but also effectively suppresses the shuttling effect of LiPSs through the synergism between physical confinement and chemical adsorption. It is revealed that the combination of Ti3C2Tx MXene and metallic Co enhances the LiPSs absorbability and accelerates the catalytic conversion of sulfur species, thereby improving sulfur utilization and electrochemical reversibility. The corresponding cells with HTCTs/Co/CNTs/S cathode retain high capacities of 901.9 mAh g−1 after 100 cycles at 0.2 C and 725.9 mAh g−1 after 500 cycles at 1.0 C. More importantly, a high areal capacity of 4.83 mAh cm−2 is achieved under a high sulfur loading of 5.8 mg cm−2 and a low E/S ratio of 4.3 µL mg−1 after 50 cycles at 0.1 C.

Porous graphene with high porosity derived from nitrogen-doped graphene aerogel for vapor adsorption and lithium–sulfur batteries

Porous graphene with high porosity derived from nitrogen-doped graphene aerogel for vapor adsorption and lithium–sulfur batteries

Metal Organic Frameworks as Polysulfide Reaction Modulators for Lithium Sulfur Batteries: Advances and Perspectives.

Currently, lithium sulfur (Li-S) battery with high theoretical energy density has attracted great research interest. However, the diffusion and loss process of intermediate lithium polysulfide during charge-discharge hindered the application of the Li-S battery in modern life. To overcome this issue, metal organic frameworks (MOFs) and their composites have been regarded as effective additions to restrain the LiPS diffusion process for Li-S battery. Benefiting from the unique structure with rich active sites to adsorb LiPS and accelerate the LiPS redox, the Li-S batteries with MOFs modified exhibit superior electrochemical performance. Considering the rapid development of MOFs in Li-S battery, this review summarizes the recent studies of MOFs and their composites as the sulfur host materials, functional interlayer, separator coating layer, and separator/solid electrolyte for Li-S batteries in detail. In addition, the promising design strategies of functional MOF materials are proposed to improve the electrochemical performance of Li-S battery.

Relay-Type Catalysis by a Dual-Metal Single-Atom System in a Waste Biomass Derivative Host for High-Rate and Durable Li-S Batteries.

An environmental-friendly and sustainable carbon-based host is one of the most competitive strategies for achieving high loading and practicality of Li-S batteries. However, the polysulfide conversion reaction kinetics is still limited by the nonuniform or monofunctional catalyst configuration in the carbon host. In this work, we propose a catalysis mode based on "relay-type" co-operation by adjacent dual-metal single atoms for high-rate and durable Li-S batteries. A discarded sericin fabric-derived porous N-doped carbon with a stacked schistose structure is prepared as the high-loading sulfur (84 wt %) host by a facile ionothermal method, which further enables the uniform anchoring of Fe/Co dual-metal single atoms. This multifunctional host enables superior lithiophilic-sulfiphilic and electrocatalytic capabilities contributed by the "relay-type" single-atom modulation effects on different conversion stages of liquid polysulfides and solid Li2S2/Li2S, leading to the suppression of the "shuttle effect", alleviation of nucleation and decomposition barriers of Li2Sx, and acceleration of polysulfide conversion kinetics. The corresponding Li-S batteries exhibit a high specific capacity of 1399.0 mA h g-1, high-rate performance up to 10 C, and excellent cycling stability over 1000 cycles. They can also endure the high sulfur loading of 8.5 mg cm-2 and the lean electrolyte condition and yield an areal capacity as high as 8.6 mA h cm-2. This work evidentially demonstrates the potential of waste biomass reutilization coupled with the design of a single-atom system for practical Li-S batteries with high energy density.

Coordination Defect‐Induced Lewis Pairs in Metal−Organic Frameworks Boosted Sulfur Kinetics for Bifunctional Photo‐Assisted Li−S Batteries

AbstractThe photo‐assisted strategy is regarded as a crucial approach to enhance the conversion kinetics of polysulfides in lithium–sulfur (Li–S) batteries. However, the development of photo‐assisted Li–S batteries still faces important challenges, such as the rapid recombination of photogenerated electron−holes on cathode and more severe shuttle effect. Herein, a breakthrough in overcoming the challenges has been made by constructing a promising photo‐assisted Li−S battery based on semiconducted metal−organic frameworks. During the discharging progress, the photoexcited electrons generated by H2BPDC ligand based on ligand‐to‐metal charge transfer (LMCT) effect, are injected into the Ti‐oxo clusters in Ti‐MOF, thereby facilitating the sulfur reduction to Li2S. And photoexcited holes are capable of promoting the decomposition kinetics of Li2S during charging. More importantly, the stronger chemical interaction between Ti‐BPDC‐d and polysulfides under light inhibits the polysulfides dissolution and shuttling, which fundamentally addresses the issue of light‐accelerated shuttling. As a result, the photo‐assisted Li–S batteries deliver a reversible capability of 1090.21 mAh g−1 at 0.2 C with a capacity retention of 82.91% over 150 cycles, and a superior rate capability of 673.58 mAh g−1 at 5 C. The findings are promising in advancing the design principles for photo‐rechargeable Li−S batteries.

Chemomechanics Engineering Promotes the Catalytic Activity of Spinel Oxides for Sulfur Redox Reaction

AbstractCooperative catalysis is a promising approach to enhance the sluggish redox kinetics of lithium polysulfides (LiPSs) for practical lithium–sulfur (Li–S) batteries. However, the elusory synergistic effect among multiple active sites makes it challenging to accurately customize the electronic structure of catalysts. Herein, a strategy of precisely tailoring eg orbitals of spinel oxides through chemomechanics engineering is porposed to regulate LiPSs retention and catalysis. By manipulating the regulable cations in MnxCo3‐xO4, it is theoretically and experimentally revealed that the lattice strain induced by the Jahn–Teller active and high‐spin Mn3+ at octahedral (Oh) sites can increase the eg occupancy of low‐spin Co3+Oh, which effectively regulates the chemical affinity toward LiPSs and establishes an unblocked channel for intrinsic charge transfer. This leads to a volcano‐type correlation between the eg occupancy at Oh sites and sulfur redox activity. Benefitting from the cooperative catalysis of dual‐active sites, MnCo2O4 with an average eg occupancy of 0.45 affords the most appropriate adsorption strength and rapid redox kinetics toward LiPSs, leading to remarkable rate performance and capacity retention for the assembled Li–S batteries. This work demonstrates the promise of chemomechanics engineering for optimizing the eg occupancy to achieve efficient sulfur redox catalysts.

Engineering Oxygen Vacancies in In2O3 with Enhanced Polysulfides Immobilization and Selective Catalytic Capability.

Lithium-sulfur (Li-S) battery is identified as an ideal candidate for next-generation energy storage systems in consideration of its high theoretical energy density and abundant sulfur resources. However, the shuttling behavior of soluble polysulfides (LiPSs) and their sluggish reaction kinetics severely limit the practical application of the current Li-S battery. In this work, a series of In2O3 nanocubes with different oxygen vacancy concentrations are designed and prepared via a facile self-template method. The introduced oxygen vacancy on In2O3 can effectively rearrange the charge distribution and enhance sulfiphilic property. Moreover, the In2O3 with high oxygen vacancy concentration (H-In2O3) can slightly slow down the solid-liquid conversion process and significantly accelerate the liquid-solid conversion process, thus reducing the accumulation of LiPSs in electrolyte and inhibiting the shuttle effect. Contributed by the unique selective catalytic capability, the prepared H-In2O3 exhibits excellent electrochemical performance when used as sulfur host. For instance, a high reversible capacity of 609 mAh g-1 is obtained with only 0.044% capacity decay per cycle over 1000 cycles at 1.0C. This work presents a typical example for designing advanced sulfur hosts, which is crucial for the commercialization of Li-S battery.

Porous Organic Framework Materials (MOF, COF, and HOF) as the Multifunctional Separator for Rechargeable Lithium Metal Batteries.

The separator is an important component in batteries, with the primary function of separating the positive and negative electrodes and allowing the free passage of ions. Porous organic framework materials have a stable connection structure, large specific surface area, and ordered pores, which are natural places to store electrolytes. And these materials with specific functions can be designed according to the needs of researchers. The performance of porous organic framework-based separators used in rechargeable lithium metal batteries is much better than that of polyethylene/propylene separators. In this paper, thethree most classic organic framework materials (MOF, COF, and HOF) are analyzed and summarized. The applications of MOF, COF, and HOF separators in lithium-sulfur batteries, lithium metal anode, and solid electrolytes are reviewed. Meanwhile, the research progress of these three materials in different fields is discussed based on time. Finally, in the conclusion, the problems encountered by MOF, COF, and HOF in different fields as well as their future research priorities are presented. This review will provide theoretical guidance for the design of porous framework materials with specific functions and further stimulate researchers to conduct research on porous framework materials.

Cellulose-based separator woven by double-layer-configuration fibers for high S-load Li-S batteries

Lithium-sulfur (Li-S) battery with high theoretical energy density, has been the most promising next-generation energy storage devices. However, the capacity of the high S-loaded cathode decays rapidly due to the shuttling of soluble polysulfide intermediates between the two electrodes, which seriously inhibits its development. In this work, polyacrylonitrile (PAN) and cellulose composite film (PAN@CE) is designed, which is woven by double-layer configuration fiber. The outer layer of fiber is mainly composed of cellulose, and the inner layer is mainly PAN. From DFT calculations and experiments, the double-layer configuration enriched with nitrogen and oxygen groups can effectively inhibit the shuttle of soluble polysulfides. Meanwhile, the interlaced network structure of PAN@CE improves the electrolyte wettability and provides abundance transport paths for ions. In addition, the film also has good thermal stability. Hence, the cycling stability of Li-S batteries with PAN@CE as separator has been greatly improved. Cellulose-based Li-S battery with 9.1 mg S loading and an E/S ratio of 6.2 μL mg−1 is assembled. Its initial area capacity is 5.67 mAh cm−2. After 200 long cycles, the area capacity keeps above 4.0 mAh cm−2.

Development of Electrolytes under Lean Condition in Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries stand out as one of the promising candidates for next-generation electrochemical energy storage technologies. A key requirement to realize high-specific-energy Li-S batteries is to implement low amount of electrolyte, often characterized by the electrolyte/sulfur (E/S) ratio. Low E/S ratio aggravates the known challenges for Li-S batteries and introduces new ones originated from the high concentration of polysulfides in limited electrolyte reservoir. In this review, the connections between the fundamental properties of electrolytes and the electrochemical/chemical reactions in Li-S batteries under lean electrolyte condition are elucidated. The emphasis is on how the solvating properties of the electrolyte affect the fate of polysulfides. Built upon the mechanistic analysis, different strategies to design lean electrolytes to improve the overall process of Li-S reactions and Li anode protection are discussed.

Balanced Mass Transfer and Active Sites Density in Hierarchical Porous Catalytic Metal-Organic Framework for Enhancing Redox Reaction in Lithium-Sulfur Batteries.

Developing highly efficient catalysts, characterized by controllable pore architecture and effective utilization of active sites, is paramount in addressing the shuttle effect and sluggish redox kinetics of lithium polysulfides (LiPSs) in lithium-sulfur batteries (LSBs), which, however, remains a formidable challenge. In this study, a hierarchical porous catalytic metal-organic framework (HPC-MOF) with both appropriate porosity and abundant exposed catalytic sites is achieved through time-controlled precise pore engineering. It is revealed that the evolution of the porous structure and catalytic site density is time-dependent during the etching processes. The moderately etched HPC-MOF-M attains heterogeneous pores at various scales, where large apertures ensure fast mass transfer and micropores inherit high-density catalytic sites, enhancing utilization and catalytic kinetics at internal catalytic sites. Capitalizing on these advantages, LSB incorporating the HPC-MOF-M interlayer demonstrates a 164.6% improvement in discharge capability and an 83.3% lower decay rate over long-term cycling at 1.0C. Even under high sulfur loading of 7.1 mg cm-2 and lean electrolyte conditions, the LSB exhibits stable cycling for over 100 cycles. This work highlights the significance of balancing the relationship between mass transfer and catalytic sites through precise chemical regulation of the porous structure in catalytic MOFs, which are anticipated to inspire the development of advanced catalysts for LSBs.

Covalent Organic Framework/Aluminum Oxide Composite Nanosheets as a Separator for High-Performance Lithium–Sulfur Batteries

Covalent Organic Framework/Aluminum Oxide Composite Nanosheets as a Separator for High-Performance Lithium–Sulfur Batteries

Ultrafine Iron Boride as a Highly Efficient Nanocatalyst Expedites Sulfur Redox Electrochemistry for High‐Performance Lithium‐Sulfur Batteries

AbstractLithium‐sulfur (Li−S) batteries have garnered significant interest as a strong contender for future energy storage, characterized by their remarkable energy density and cost‐effectiveness. However, the sluggish conversion kinetics of the polysulfide intermediates, compounded with their shuttling behaviors, pose considerable challenges in sulfur electrochemistry. Herein, we develop a novel iron monoboride (FeB) electrocatalyst for boosting sulfur reactions and enhancing Li−S battery performance. The ultrafine powdery FeB affords abundant and fully exposed active interfaces for host‐guest interactions. Meanwhile, the intrinsic high conductivity of FeB, combined with its strong adsorption and catalytic activity to polysulfides, enables substantial inhibition of the shuttle effect and enhancement of conversion kinetics. As a result, sulfur electrodes equipped with the FeB nanocatalyst realize excellent cyclability with a minimal capacity fading of 0.04 % per cycle over 500 cycles, as well as favorable rate capability up to 7 C. Moreover, decent areal capacity and cycling stability can be also achieved under high‐loading (5.1 mg cm−2) and limited‐electrolyte (7.0 mL g−1) configurations. This study presents a facile approach and insightful perspective on nanostructured metal boride for highly efficient sulfur electrocatalysis, holding good promise for the advancement of high‐performance Li−S batteries.