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As a critical role in battery systems, polymer binders have been shown to efficiently suppress the lithium polysulfide shuttling and accommodate volume changes in recent years. However, preparation processes and safety, as the key criterions for Li‐S batteries' practical applications, still attract less attention. Herein, an aqueous multifunction binder (named PEI‐TIC) is prepared via an easy and fast epoxy‐amine ring‐opening reaction (10 min), which can not only give the sulfur cathode a stable mechanical property, a strong chemical adsorption and catalytic conversion ability, but also a fire safety improvement. The Li‐S batteries based on the PEI‐TIC binder display a high discharge capacity (1297.8 mAh g−1), superior rate performance (823.0 mAh g−1 at 2 C), and an ultralow capacity decay rate of 0.035% over more than 800 cycles. Even under 7.1 mg cm−2 S‐loaded, the PEI‐TIC electrode can also achieve a high areal capacity of 7.2 mA h g−1 and excellent cycling stability, confirming its application potential. Moreover, it is also noted that TG‐FTIR test is performed for the first time to explore the flame‐retardant mechanism of polymer binders. This work provides an economically and environmentally friendly binder for the practical application and inspires the exploration of the flame‐retardant mechanism of all electrode components. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li–S) batteries have emerged as a next-generation battery technology owing to their prospects of high capacity and energy density. They, however, suffer from rapid capacity decay due to the shuttling of reaction intermediate species: Li polysulfides (LiPSs). One of the more important and intriguing PSs is the tri-sulfur radical (S3•−), observed mainly in high-donor number (DN) solvent-based electrolytes. Although this radical has been proposed to be crucial to full active material (AM) utilization, there is currently no direct evidence of the impact of S3•− on cycling stability. To gain more insight into the role of the S3•−, we studied the use of radical traps in low and high DN solvent-based electrolytes by operando Raman spectroscopy. The traps were based on nitrone and iminium cation, and S3•− was indeed successfully trapped in ex situ analysis. However, it was the ionic liquid-based trap, specifically pyridinium, that effectively suppressed S3•− during battery operation. Overall, the PS formation was altered in the presence of the traps and we confirmed the impact of S3•− formation on the Li–S battery redox reactions and show how the trapping correlates with Li–S battery performance. Therefore, stabilization of the S3•− might be a path to improved Li–S batteries.

Abstract Batteries that utilize low‐cost elemental sulfur and light metallic lithium as electrodes have great potential in achieving high energy density. However, building a lithium–sulfur (Li–S) full battery by controlling the electrolyte volume generally produces low practical energy because of the limited electrochemical Li–S redox. Herein, the high energy/high performance of a Li–S full battery with practical sulfur loading and minimum electrolyte volume is reported. A unique hybrid architecture configured with Ni–Co metal alloy (NiCo) and metal oxide (NiCoO2) nanoparticles heterogeneously anchored in carbon nanotube‐embedded self‐standing carbon matrix is fabricated as a host for sulfur. This work demonstrates the considerable improvement that the hybrid structure's high conductivity and satisfactory porosity promote the transport of electrons and lithium ions in Li–S batteries. Through experimental and theoretical validations, the function of NiCo and NiCoO2 nanoparticles as an efficient polysulfide mediator is established. These particles afford polysulfide anchoring and catalytic sites for Li–S redox reaction, thus improving the redox conversion reversibility. Even at high sulfur loading, the nanostructured Ni–Co metal alloy and metal oxide enable to have stable cycling performance under lean electrolyte conditions both in half‐cell and full‐cell batteries using a graphite anode.

The sulfured dicyclopentadiene (S-DCPD) is a promising cathode candidate for Li-S batteries. Enlightened by the function of KI in dye-sensitized solar cells, we employ KI as a catalyst in the preparation of S-DCPD without eliminating it in the assembly of Li-S batteries. As a result, the sulfurizing reaction proceeds more completely at a lower temperature. The as-prepared material exhibits a different light response to the blank sample, changing from a higher energy level to a lower one. And the electrochemistry is greatly elevated as well. Theoretical calculations validate that KI plays the key role by altering the electron transmitting path. We can thus unify the behaviors of KI in the field of heat, light, and electricity, phenomenally. Furthermore, we investigate the morphology changes of the electrode by dipping it in an ordinary solution and subjecting it to a cycle calendar life in the electrolyte, respectively. As a result, we make clear that the difference of the behaviors between ordinary solutions and electrolytes is also in associated with the electronic path of KI.

The complex multistep electrochemical reactions of lithium polysulfides and the solid–liquid–solid phase transformation involved in the S8 to Li2S reactions lead to slow redox kinetics in lithium–sulfur batteries (Li–S batteries). However, some targeted researches have proposed strategies requiring the introduction of significant additional inactive components, which can seriously affect the energy density. Whereas polymer binders, proven to be effective in suppressing shuttle effects and constraining electrode volume expansion, also have promising potential in enhancing Li–S batteries redox kinetics. Herein, a novel aqueous polymer binder is prepared by convenient amidation reaction of fully biomaterials, utilizing its inherent rich amide groups for chemisorption and redox mediating ability of thiol groups to achieve adsorption redox-mediated synergism for efficient conversion of polysulfides. Li–S batteries based on N-Acetyl-L-Cysteine-Chitosan (NACCTS) binder exhibit high initial discharge specific capacity (1260.1 ​mAh ​g−1 at 0.2 ​C) and excellent cycling performance over 400 cycles (capacity decay rate of 0.018% per cycle). In addition, the batteries exhibit great areal capacity and stable capacity retention of 83.6% over 80 cycles even under high sulfur loading of 8.4 ​mg ​cm−2. This work offers a novel perspective on the redox-mediated functional design and provides an environmentally friendly biomaterials-based aqueous binder for practical Li–S battery.

Highlights Compared 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.

Lithium–sulfur (Li–S) batteries have gained considerable attention for high theoretical specific capacity and energy density. However, their development is hampered by the poor electrical conductivity of sulfur and the shuttle of polysulfides. Herein, the acidified bamboo-structure carbon nanotubes (BCNTs) were mixed with polyvinylidene difluoride and pyrolyzed at high-temperature to obtain the fluorinated bamboo-structure carbon nanotubes (FBCNTs), which were compounded with sulfur as the cathode. The prepared S@FBCNTs with sulfur loading reaching 74.2 wt.% shows a high initial specific capacity of 1407.5 mAh·g−1 at the discharge rate of 0.1 C. When the discharge rate was increased to 5 C, the capacity could be maintained at 622.3 mAh·g−1. The electrical conductivity of carbon nanotubes is effectively improved by semi-ionic C–F bonds formed by the doped F atoms and carbon atoms. Simultaneously, the surface of the F-containing carbon tubes exhibits strong polarity and strong chemisorption effect on polysulfides, which inhibits the shuttle effect of Li–S batteries. [ABSTRACT FROM AUTHOR]

High specific capacity and long cycle life are the key to high-performance lithium–sulfur (Li–S) batteries, but they are hard to achieve simultaneously due to the notorious polysulfide shuttle effect. Transition metal oxide nanocatalysts are expected to help address the above issue, but their low conductivity and cumbersome synthesis process limit their application. Here, we propose a defect engineering strategy to induce electron rearrangement by heteroatom doping. Boron-doped spinel-type oxide (B-ZnCo2O4‑x) is synthesized by a two-step hydrothermal method for separator modification. The boron-produced oxygen vacancy (OV) increases unsaturated sites by changing the electron cloud density, and therefore, the B-ZnCo2O4‑x nanocatalyst can reduce the reaction energy barrier and accelerate the nucleation and activation rate of Li2S. Meanwhile, the unique pore defects effectively increase the Li+ flux and ensure battery performance at a high rate and high sulfur loading. The battery equipped with a B-ZnCo2O4‑x-modified separator delivered an initial specific capacity of 1108 mAh g–1 at 0.2 C and a capacity retention rate of 80.4% at 0.5 C after 200 cycles. In particular, at a high sulfur loading of 10.0 mg cm–2, the battery yielded a first-cycle capacity of 1321.9 mAh g–1. This work demonstrates that boron-doping-enabled defect engineering is an effective strategy to improve the catalytic activity of transition metal oxides for application in Li–S batteries. [ABSTRACT FROM AUTHOR]

Li–S batteries and Na–S batteries attract wide attention because of high specific capacity, rich resources and environmental friendliness, but poor rate performance limits their development. Single atoms perform as active sites and promote redox reaction process of sulfur, which are benefit for improving rate performance of Li–S batteries and Na–S batteries. However, many researches only focus on transition metal atoms instead of non-transition metal atoms. Sn atoms are introduced on carbon surface to obtain C/Sn composites and electrochemical performance of C/Sn/S composites in Li–S batteries and Na–S batteries is studied in this paper. As for comparison, electrochemical performance of C/S without Sn atom modified is also studied. Results show that C/Sn/S composite electrodes possess higher rate performance than C/S composite electrodes in both Li–S batteries (359 mAh·g−1 at 20C) and Na–S batteries (151 mAh·g−1 at 20C). High-rate performance of C/Sn/S composite electrodes in Li–S batteries is attributed to catalytic abilities of active Sn atoms and high conductivity of carbon. Researches provide references for structure control and application of carbon composites with non-transition metal atom modified. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries have received extensive attention due to their numerous advantages, including a high theoretical specific capacity, high energy density, abundant reserves of sulfur in cathode materials, and low cost. Li–S batteries also face several challenges, such as the insulating properties of sulfur, volume expansion during charging and discharging processes, polysulfide shuttling, and lithium dendritic crystal growth. In this study, a composite of a porous multi-site diatomite-loaded graphene oxide material and a PAN fiber membrane is developed to obtain a porous and high-temperature-resistant GO/diatomite/polyacrylonitrile functional separator (GO/DE/PAN) to improve the electrochemical performance of Li–S batteries. The results show that the use of GO/DE/PAN helps to inhibit lithium phosphorus sulfide (LPS) shuttling and improve the electrolyte wetting of the separator as well as the thermal stability of the battery. The initial discharge capacity of the battery using GO/DE/PAN is up to 964.7 mAh g−1 at 0.2 C, and after 100 cycles, the reversible capacity is 683 mAh g−1 with a coulombic efficiency of 98.8%. The improved electrochemical performance may be attributed to the porous structure of diatomite and the layered composite of graphene oxide, which can combine physical adsorption and spatial site resistance as well as chemical repulsion to inhibit the shuttle effect of LPS. The results show that GO/DE/PAN has great potential for application in Li–S batteries to improve their electrochemical performance. [ABSTRACT FROM AUTHOR]

The critical factors that limit the electrochemical performance of lithium-sulfur (Li-S) batteries are mainly the "shuttle effect" of polysulfides and the slow redox reaction between lithium polysulfides (LiPSs). Herein, a nano-sphere-type material self-assembled from tin disulfide nanosheets is designed and applied to the Li-S cell separator in this work. The SnS2@PP modified separator not only acts as a dual restriction for LiPSs by chemisorption and physical barrier. At the same time, it improves the catalytic activity of the redox reaction between LiPSs. The SnS2 has extremely high electrochemical activity. There, a portion of the lithium ions can be inserted into SnS2 to form LixSnS2 and contribute to the capacity during the first discharge of the battery. In addition, LixSnS2 possesses a high degree of stability, and it does not undergo further de-alloying reactions even at the high potential of the Li-S cell. The benefit is that the steady-state LixSnS2 acts as a lithium-containing substance. It can form special Li+ channels on the surface of the separator, thus greatly improving the efficiency of Li+ transport. The results showed that the SnS2@PP-based cell exhibited extremely high initial discharge specific capacity (1477 mAh g−1 at 0.1 C) and excellent rate performance (631 mAh g−1 at 5 C). Even after 1000 cycles at 2 C, the cell exhibited a low decay rate of 0.06% per cycle on average. In addition, the superior electrochemical performance was obtained even with a high sulfur loading of 5.1 mg cm−2 and low electrolyte of E/S = 8 μL mg−1. [ABSTRACT FROM AUTHOR]

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[Display omitted] • The ultrathin MgB 2 nanosheets were prepared by ultrasonic-assisted exfoliation technology. • MgB 2 @PP as separator contributes to the adsorption and catalytic conversion of polysulfides and inhibits the shuttle effect. • MgB 2 @PP as separator significantly improves the sulfur utilization, high specific capacity and cycle stability in Li-S batteries. The separator is an important component in lithium-sulfur (Li-S) batteries. However, the conventional polypropylene (PP) separators have the problem of easy shuttling of lithium polysulfide (LiPSs). Herein, ultrathin magnesium boride (MgB 2) nanosheets were prepared by ultrasonic-assisted exfoliation technology, and were suction-filtered onto a separator to serve as a separator modification layer. The introduction of a microporous structure into MgB 2 nanosheets after ultrasonic peeling increases the specific surface area and pore volume, with more adsorption sites, which can fully utilize the surface adsorption/catalytic performance of MgB 2 for LiPSs and accommodate the volume expansion of lithium sulfide (Li 2 S). Therefore, MgB 2 @PP as a separator significantly improves the sulfur utilization and cycle stability in Li-S batteries. When the MgB 2 @PP separator is used, the reversible specific capacity of the assembled Li-S battery at 0.1 C (current rate) is 1184 mAh/g, and the specific capacity at 2 C is 732 mAh/g. After 500 cycles at 2 C, it remains at 497 mAh/g. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries (Li–S batteries) have a high theoretical capacity density. However, due to the solubility of long‐chain polysulfides migration between the positive and negative electrodes driven by concentration gradients, the cycle stability of lithium–sulfur batteries is compromised, hindering their practical application. To mitigate the shuttle effect and enhance the electrochemical performance of Li–S batteries, a hollow microflower (MF) Mo2C/MoO2 heterostructure is synthesized using a two‐step calcining method. The presence of a hetero‐interface improves the electrical conduction rate, facilitating more effective charge transfer at the interface between heterogeneous components. Additionally, the increased catalytic active sites enhance the conversion of polysulfides and promote the catalytic capability. As a result, Li–S batteries with H‐Mo2C/MoO2/nitrogen‐doped carbon MFs as additives in the cathode exhibit excellent rate performance and good cycling stability. After 100 cycles at 0.2C, the capacity remains at 1071.6 mAh g−1, with a capacity retention rate of 90.6%. Notably, the Li–S batteries demonstrate a capacity decay of only 0.011% per cycle over 1000 cycles at 1C, with a specific capacity of 790 mAh g−1 retained after the cycling process. In this work, a rational approach is provided to fabricating transition‐metal carbon‐oxide heterostructures with an optimized structure to enhance the performance of Li–S batteries. [ABSTRACT FROM AUTHOR]

The fabrication of cathodes with carbonized Agave tequilana bagasse for Li–S batteries is performed for the first time. Three porous carbonaceous structures are developed and studied to elucidate the best carbon textural properties in terms of their surface area and pore size distribution: hierarchical porosity, highly microporous, and nonporous material, for sulfur hosting in Li–S cathodes. N2 physorption, scanning electron microscopy, infrared spectroscopy, and potentiometric titrations analysis are performed to determine the textural, morphology, and physicochemical properties. The fabricated coin cells, CR2032, with cathodes made of mesoporous carbons, display a high discharge current (≈1600 mAh g−1), superior performance, and cyclability up to 250 cycles. The performance of batteries is found to be strongly influenced by surface area and pore size of the carbon materials. The carbonized tequila bagasse hosting sulfur can be very useful to fabricate cathodes for Li–S batteries with high initial capacity and cycling stability. [ABSTRACT FROM AUTHOR]

The rapid developments of the Internet of Things (IoT) and portable electronic devices have created a growing demand for flexible electrochemical energy storage (EES) devices. Nevertheless, these flexible devices suffer from poor flexibility, low energy density, and poor dynamic stability of power output during deformation, limiting their practical applications. Carbon nanofibers (CNFs) with high conductivity, good flexibility, and large‐scale preparation are regarded as promising electrodes for flexible EES devices. Based on the issues of current flexible EES devices, this review presents various strategies from the design of CNFs‐based electrodes to the fabrication of devices and overviews their applications in various flexible metal ion/air batteries (Li/Na/K‐ion batteries, Li‐S batteries, metal–air batteries, and other novel secondary batteries) and supercapacitors. Finally, the remaining challenges and perspectives on the CNFs‐based flexible EES devices are proposed to provide guidance for the researchers concentrating on high‐performance flexible EES devices. [ABSTRACT FROM AUTHOR]

The development of low‐temperature lithium–sulfur batteries (LSB) has been suppressed by rather poor sulfur utilization and cycle performance, caused by planar Li2S growth, hindered lithium polysulfides (LiPSs) transformation, and poor stability of the anode. Recently, low‐concentration electrolytes (LCE) have been employed as promising solutions to solve the above issues. However, aggregation and deposition behavior of polysulfides have been rarely studied. In this work, by comparing the performance of 0.1 and 1 m LiFSI electrolytes, LCEs are proven beneficial for low‐temperature LSBs via new fundamental insights. According to growth pattern analyses by both morphology observation and theoretical models, Li2S nucleation in LCEs switch into progressive mode with less initial nuclei, which favors the vertical growth of Li2S, resulting in a more complete lithium–sulfur conversion reaction under cold conditions. Through visual experiments, computational simulation, and progressive electrochemical impedance spectroscopy, the ability of LCEs to suppress LiPSs clustering is supported and this anti‐clustering ability effectively enhances the Li–S conversion reaction kinetics. Moreover, in LCEs a protective SEI with LiF and Li2S/Li2S2 is likely to form on and stabilize the anode. As a whole, the boosting effect and the mechanism of LCEs enlighten future designs on low‐temperature electrolytes for high‐performance cryogenic LSBs. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries are among the promising high‐capacity candidates owing to the superior theoretical capacity of sulfur, when compared with conventional cathodes such as LiCoO2. However, several issues must be addressed before these batteries can be considered fully operational. Major issues regard the insulating nature of sulfur and the so‐called shuttle effect of soluble polysulfides, which dramatically reduces the cathode capacity upon cycling. Herein, three carbon‐containing polymer‐derived ceramic aerogels are characterized belonging to the Si‐C‐O and Si‐C‐N systems, infiltrated with sulfur to work as cathodes for Li‐S batteries. The electrochemical performances are evaluated in relation to the microstructural and chemical features of such materials. In particular, the effect of the pore size of the ceramic matrices on the shuttling behavior of polysulfides is investigated. Despite the high initial specific capacities exceeding hundreds of mAh g−1, all types of cathodes show stable capacities in the 60–120 mAh g−1 range after 100 cycles. [ABSTRACT FROM AUTHOR]

The conversion of agricultural residual biomass into biochar as a sulfur host material for Li-S batteries is a promising approach to alleviate the greenhouse effect and realize waste resource reutilization. However, the large-scale application of pristine biochar is hindered by its low electrical conductivity and limited electrocatalytic sites. This paper addressed these challenges via the construction of Fe-N co-doped biochar (Fe-NOPC) through the copyrolysis of sesame seeds shell and ferric sodium ethylenediaminetetraacetic acid (NaFeEDTA). During the synthesis process, NaFeEDTA was used as an extra carbon resource to regulate the chemical environment of N doping, which resulted in the production of high contents of graphitic, pyridinic, and pyrrolic N and Fe-Nx bonds. When the resulting Fe-NOPC was used as a sulfur host, the pyridinic and pyrrolic N would adjust the surface electron structure of biochar to accelerate the electron/ion transport, and the electropositive graphitic N could be combined with sulfur-related species via electrostatic attraction. Fe-Nx could also promote the redox reaction of lithium polysulfides due to the strong Li-N and S-Fe bonds. Benefiting from these advantages, the resultant Fe-NOPC/S cathode with a sulfur loading of 3.8 mg·cm−2 delivered an areal capacity of 4.45 mAh·cm−2 at 0.1C and retained a capacity of 3.45 mAh·cm−2 at 1C. Thus, this cathode material holds enormous potential for achieving energy-dense Li-S batteries. [ABSTRACT FROM AUTHOR]

A nitrogen-phosphorus dual-doped auricularia auricula carbon (NP-AC) matrix was prepared through hydrothermal treatment using natural auricularia auricula as raw material and medium solution. Yeast was introduced and cultured by the auricularia auricula liquid medium. The NP-AC/S composite was prepared through further freeze-drying, carbonization, activation and compounding with sulfur procedures. The composition and microstructure of samples was characterized by X-ray diffraction (XRD), raman and X-ray photoelectron spectroscopy (XPS). The morphology was observed under scanning electron microscope (SEM) and transmission electron microscopy (TEM) method. The specific surface area was analyzed using nitrogen adsorption/desorption test. The weight ratio of sulfur was measured through thermogravimetric (TG) analysis. The original structure and composition of biomass were improved by yeast fermentation and the auricularia auricula block structure with low porosity was modified. The electrochemical performance of NP-AC/S composite in Li-S batteries was systematically explored. After 100 cycles at 0.2C current density, there was still nearly 1000 mAh g−1 reversible capacity, holding a capacity retention rate of more than 84 %. The cycle performance and rate performance were both far better than the ordinary activated carbon materials.

Abstract Lithium‐Sulfur (Li‐S) batteries as the next‐generation battery system have an ultrahigh theoretical energy density. However, the limited conversion of polysulfides in sulfur cathodes deteriorates the performance of Li‐S batteries. In this study, we develop a novel titanium nitride (TiN) catalyst for sulfur cathodes via atomic layer deposition (ALD). The synthesized ALD‐TiN catalyst shows controllable ultrafine particle size (

Fluorographene exhibits a rich chemistry and a wide range of applications in energy storage devices. This review, which is based on our lab results acquired in the last decade, explores the synthesis, properties, and performance of fluorographene-based materials in supercapacitors and batteries. Fluorographene can be prepared through mechanical or chemical delamination of graphite fluoride, allowing for scalable synthesis and further chemical processing. The chemical versatility of fluorographene enables a wide portfolio of chemical reactions, leading to a new class of graphene derivatives. Graphene acid, a product of fluorographene chemistry, exhibits excellent specific capacitance, cycling stability, and rate capability. Hybridizing graphene acid with metal-organic frameworks can achieve even higher energy and power densities. Furthermore, nitrogen-doped graphene derived from fluorographene demonstrates remarkable capacitive behavior, making it an efficient electrode material for supercapacitors. Additionally, fluorographene-based materials, such as graphene acid, graphene-sulfur hybrids, and graphene-based anodes, have exhibited outstanding performance in lithium-ion and lithium-sulfur batteries. The scalable synthesis, high performance, and versatility of fluorographene-derived materials render them attractive for practical energy storage applications. The unique properties and wide range of chemistries offered by fluorographene chemistry open new possibilities for improving advanced energy storage devices.

Highly concentrated electrolytes have been studied to prevent the leaching diffusion of lithium (Li) polysulfides from sulfur (S) cathodes in Li–S batteries. Additionally, high-concentration electrolytes suppress the growth of Li dendrites at Li anodes. In this study, an ether-based high-concentration electrolyte was developed, enabling a microporous activated carbon–S composite cathode to achieve near-theoretical capacity performance and a long cycle life. The reference electrolyte was a high-concentration solution of Li bis(fluorosulfonyl)imide (LiFSI) in 1,2-dimethoxyethane (DME), known for its suitability for the stable dissolution and deposition of Li. However, its high viscosity impeded full penetration into the activated carbon–S composite cathode. To enhance the reversibility of the activated carbon–S composite cathode, we optimized the LiFSI-based electrolyte by adding hydrofluoroether (HFE) to reduce the viscosity and adjusting the LiFSI concentration to prevent the dissolution of Li polysulfides. Furthermore, the addition of Li difluoro(oxalate)borate (LiDFOB) to this electrolyte stabilized the cycling performance for over 100 cycles. When applied to a 1-Ah-class pouch cell, the electrolyte achieved an energy density of greater than 300 Wh kg−1.

Intensive increases in electrical energy storage are being driven by electric vehicles (EVs), smart grids, intermittent renewable energy, and decarbonization of the energy economy. Advanced lithium–sulfur batteries (LSBs) are among the most promising candidates, especially for EVs and grid-scale energy storage applications. In this topical review, the recent progress and perspectives of practical LSBs are reviewed and discussed; the challenges and solutions for these LSBs are analyzed and proposed for future practical and large-scale energy storage applications. Major challenges for the shuttle effect, reaction kinetics, and anodes are specifically addressed, and solutions are provided on the basis of recent progress in electrodes, electrolytes, binders, interlayers, conductivity, electrocatalysis, artificial SEI layers, etc. The characterization strategies (including in situ ones) and practical parameters (e.g., cost-effectiveness, battery management/modeling, environmental adaptability) are assessed for crucial automotive/stationary large-scale energy storage applications (i.e., EVs and grid energy storage). This topical review will give insights into the future development of promising Li–S batteries toward practical applications, including EVs and grid storage.

Abstract Thanks to the significantly higher energy density compared with universal commercialized Li‐ion batteries, lithium–sulfur (Li–S) batteries are being investigated for use in prospective energy storage devices. However, the inadequate electrochemical kinetics of reactants and intermediates hinder commercial utilization. This limitation results in substantial capacity degradation and short battery lifespans, thereby impeding the battery's power export. Meanwhile, the capacity attenuation induced by the undesirable shuttle effect further hinders their industrialization. Considerable effort has been invested in developing electrocatalysts to fix lithium polysulfides and boost their conversion effectively. In the conventional process, the planar electrodes are prepared by slurry‐casting, which limits the electron and ion transfer paths, especially when the thickness of the electrodes is relatively large. Compared with traditional manufacturing methods, direct ink writing (DIW) technology offers unique advantages in both geometry shaping and rapid prototyping, and even complex three‐dimensional structures with high sulfur loading. Hence, this review presents a detailed description of the current developments in terms of Li–S batteries in DIW of metal‐based electrocatalysts. A thorough exploration of the behavior chemistry of electrocatalysis is provided, and the adhibition of metal‐based catalysts used for Li–S batteries is summarized from the aspect of material usage and performance enhancement. Then, the working principle of DIW technology and the requirements of used inks are presented, with a detailed focus on the latest advancements in DIW of metal‐based catalysts in Li–S battery systems. Their challenges and prospects are discussed to guide their future development.

Highlights This review systematically analyzes the effect of the electrolyte-to-sulfur ratios on battery energy density and the challenges for sulfur reduction reactions under lean electrolyte conditions. The strengths and limitations of different transition metal compounds are systematically presented and discussed from a fundamental perspective. Three promising strategies for sulfur hosts that act as anchors and catalysts are proposed to boost lean electrolyte Li–S battery performance.

Highlights A comprehensive discussion of the approaches for developing carbon-based sulfur hosts is presented, encompassing structural design and functional optimization. The recent implementation of effective machine learning methods in discovering carbon-based sulfur hosts has been systematically examined. The challenges and future directions of carbon-based sulfur hosts for practically application have been comprehensively discussed. A summary of the strengths and weaknesses, along with the outlook on carbon-based sulfur hosts for practical application has been incorporated.

The inferior shuttle effect of intermediate lithium polysulfides and the sluggish kinetics of sulfur redox reaction are two serious puzzles for the application of lithium-sulfur batteries. Herein, energy band alignment is combined with oxygen vacancies engineering to obtain TiO2 anatase/rutile homojunction (A/R-TiO2) with effective immobilization and high-efficiency catalytic conversion of polysulfides. Theoretical calculations and experiments reveal that the near perfect energy band alignment in A/R-TiO2 is conducive to fluent charge transfer and high catalytic activity, while the rich oxygen vacancies are engineered to provide abundant active sites for anchoring and accelerating conversion of soluble polysulfides. As a result, a battery with A/R-TiO2-modified separator delivers a marked sulfur utilization (1210 mAh g-1 at 0.1 C and 689 mAh g-1 at 1 C, 3.75 mg cm-2) and a high capacity retention of 63% over 300 cycles at 0.5 C (3.25 mg cm-2). More importantly, the A/R-TiO2-modified separator endows the pouch cell with a high capacity of 128.5 mAh at 0.05 C with a lean electrolyte/sulfur ratio for practical application (S loading: 4 mg cm-2). [ABSTRACT FROM AUTHOR]

The serious shuttle effect and sluggish reaction kinetics intrinsically handicap the practical application of Li-S batteries. Herein, a unique 3D hierarchically porous Mott-Schottky electrocatalyst composed of W2C quantum dots (QD) spatially confined in nitrogen-doped graphene microspheres (NGM) is proposed for regulating the kinetics of sulfur electrochemistry. Experimental and theoretical results disclose a spontaneous charge rearrangement and induce built-in electric field across the W2C QD/NGM heterojunction interface, contributing to reduced energy barrier for both polysulfides reduction and Li2S oxidation during entitle discharge/charge processes. Furthermore, the ultrasmall W2C QD with high electrocatalytic activity and superior conductivity can promote the conversion of S species, while the hierarchically porous microspheres assembled from wrinkled graphene nanosheets not only can efficiently inhibit the polysulfides shuttling via multiple spatial confinement, but also provide abundant inner space for stable reservation of active S, highly conductive networks, and maintain the structural integrity of cathode during consecutive cycling. Consequently, Li-S batteries employed with the designed W2C QD/NGM-based cathode exhibit outstanding electrochemical properties even at a high sulfur loading. The superior performance combined with the simplicity of the synthesis process represents a promising strategy for the rational design of advanced electrocatalyst for energy applications. [ABSTRACT FROM AUTHOR]

The cubic‐garnet (Li7La3Zr2O12, LLZO) lithium–sulfur battery shows great promise in the pursuit of achieving high energy densities. The sulfur used in the cathodes is abundant, inexpensive, and possesses high specific capacity. In addition, LLZO displays excellent chemical stability with Li metal; however, the instabilities in the sulfur cathode/LLZO interface can lead to performance degradation that limits the development of these batteries. Therefore, it is critical to resolve these interfacial challenges to achieve stable cycling. Here, an innovative gel polymer buffer layer to stabilize the sulfur cathode/LLZO interface is created. Employing a thin bilayer LLZO (dense/porous) architecture as a solid electrolyte and significantly high sulfur loading of 5.2 mg cm−2, stable cycling is achieved with a high initial discharge capacity of 1542 mAh g−1 (discharge current density of 0.87 mA cm−2) and an average discharge capacity of 1218 mAh g−1 (discharge current density of 1.74 mA cm−2) with 80% capacity retention over 265 cycles, at room temperature (22 °C) and without applied pressure. Achieving such stability with high sulfur loading is a major step in the development of potentially commercial garnet lithium–sulfur batteries. [ABSTRACT FROM AUTHOR]

The simultaneous engineering of sulfur cathode and Li anode is critical for electrolyte‐starved high energy density Li–S batteries, in which slow electrochemical conversions and side chemical reactions of dead sulfur are found to be the determining factors in limiting the sulfur utilization, corresponding to the poor reversible capacity of Li–S batteries. Herein, this work challenges the conventional wisdom of heterogeneous and homogeneous catalyses in Li–S batteries and proposes the concept of integrated–heterogeneous catalysis to simultaneously scavenge the dead sulfur and dead lithium to compensate the active materials sulfur and lithium loss simply through adding a small amount of ZnI2 into conventional electrolyte of Li–S cells. Regulated by integrated–heterogeneous catalysis, over 1300 h of cycling is realized in Li||Li symmetric cells, revealing superb compatibility of the ZnI2‐incorporated electrolyte with lithium metal. Meanwhile, the ZnI2 shows good prospects in promoting the reutilization of dead sulfur in both theoretical calculation and experimental tests. Practically, a high initial capacity of 1170 mAh g−1 with decent cycling stability is achieved in electrolyte‐starved and high‐loading pouch cells (5.0 µL mg−1 and 5.2 mg cm−2). [ABSTRACT FROM AUTHOR]

The practical application of Lithium–Sulfur batteries largely depends on highly efficient utilization and conversion of sulfur under the realistic condition of high‐sulfur content and low electrolyte/sulfur ratio. Rational design of heterostructure electrocatalysts with abundant active sites and strong interfacial electronic interactions is a promising but still challenging strategy for preventing shuttling of polysulfides in lithium–sulfur batteries. Herein, ultrathin nonlayered NiO/Ni3S2 heterostructure nanosheets are developed through topochemical transformation of layered Ni(OH)2 templates to improve the utilization of sulfur and facilitate stable cycling of batteries. As a multifunction catalyst, NiO/Ni3S2 not only enhances the adsorption of polysulfides and shorten the transport path of Li ions and electrons but also promotes the Li2S formation and transformation, which are verified by both in‐situ Raman spectroscopy and electrochemical investigations. Thus, the cell with NiO/Ni3S2 as electrocatalyst delivers an area capacity of 4.8 mAh cm−2 under the high sulfur loading (6 mg cm−2) and low electrolyte/sulfur ratio (4.3 μL mg−1). The strategy can be extended to 2D Ni foil, demonstrating its prospects in the construction of electrodes with high gravimetric/volumetric energy densities. The designed electrocatalyst of ultrathin nonlayered heterostructure will shed light on achieving high energy density lithium–sulfur batteries. [ABSTRACT FROM AUTHOR]

The shuttling effect of polysulfide and its sluggish reaction kinetics are the primary issues with lithium–sulfur (Li–S) batteries. In this work, an improved coimpregnation technique was used to add cobalt atoms to nitrogen-doped carbon nanotubes (Co-NCNTs) and compound them onto mesoporous silicon (SiO2). Co-NCNTs/SiO2 composites were then used as modification materials for Li–S battery separators, which were capable of physical and chemical adsorption of lithium polysulfide (LiPSs). Between silica and LiPSs, there is chemical as well as physical adsorption in the mesoporous structure of the mesoporous silica. Cobalt has a significant capacity for adsorbing LiPSs, and the cobalt site possesses catalytic activity that can promote the redox kinetics of LiPSs. NCNTs have better electrical conductivity and a dense network structure, which facilitates electrolyte penetration and Li+ transfer. As a result, Li–S batteries built with a modified separator made of Co-NCNTs/SiO2 exhibit good capacity, cycle performance, and multiplier performance, with a 1314 mA h g–1 initial capacity at 0.2 C. After 200 cycles at 1 C, the capacity is 448 mA h g–1. This work proved that Co-NCNTs/SiO2 can efficiently adsorb LiPSs and accelerate their transformation, which slows down polysulfides' shuttle effect and speeds up their slow kinetics. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The application of high‐performance lithium‐sulfur (Li‐S) batteries is severely influenced by the "shuttle effect" of polysulfides and the volume change of sulfur cathode. Herein, two different polymeric binders SOT‐A and SOT‐C with three‐dimensional network structure containing polar groups (sulfhydryl groups, amide groups and amino groups) are synthesized by the nucleophilic ring‐opening polymerization (ROP) of thiolactone with amino groups. The network structure formed by hydrogen bonds and functional groups can resist the volume change of the cathode. The sulfhydryl groups and the S—S bond formed by oxidative dehydrogenation of sulfhydryl group participate in the charge and discharge process of the battery as active materials, which improves the discharge specific capacity of the battery. Polar functional groups have strong chemisorption on polysulfides and effectively inhibit the "shuttle effect". The electrochemical performances of Li‐S batteries containing SOT‐A and SOT‐C binders are significantly enhanced. At 1 C rate, the batteries achieve initial discharge specific capacity of 871 and 837 mAh·g–1, respectively, and have 83.9% and 62.5% capacity retention after 500 cycles. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The application of high‐performance lithium‐sulfur (Li‐S) batteries is severely influenced by the "shuttle effect" of polysulfides and the volume change of sulfur cathode. Herein, two different polymeric binders SOT‐A and SOT‐C with three‐dimensional network structure containing polar groups (sulfhydryl groups, amide groups and amino groups) are synthesized by the nucleophilic ring‐opening polymerization (ROP) of thiolactone with amino groups. The network structure formed by hydrogen bonds and functional groups can resist the volume change of the cathode. The sulfhydryl groups and the S—S bond formed by oxidative dehydrogenation of sulfhydryl group participate in the charge and discharge process of the battery as active materials, which improves the discharge specific capacity of the battery. Polar functional groups have strong chemisorption on polysulfides and effectively inhibit the "shuttle effect". The electrochemical performances of Li‐S batteries containing SOT‐A and SOT‐C binders are significantly enhanced. At 1 C rate, the batteries achieve initial discharge specific capacity of 871 and 837 mAh·g–1, respectively, and have 83.9% and 62.5% capacity retention after 500 cycles. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries have high theoretical energy density and are regarded as next‐generation batteries. However, their practical energy density is much lower than the theoretical value. In previous studies, the increase of the areal capacity of the cathode and the decrease of the negative/positive ratio can be well achieved, yet the energy density shows no corresponding increase. The main reason is the difficulty in decreasing electrolyte dosage because lean electrolyte inevitably causes the deterioration of reaction kinetics and sulfur utilization. Thus, the electrolyte/active material ratio in the reported works is usually higher than 10 µL mg−1, much higher than that in Li‐ion batteries (usually lower than ≈0.3 µL mg−1 for cathode). Although many works have focused on this topic, a systematic discussion is still rare. This review systematically discusses the key challenges and solutions for assembling high‐performance lean‐electrolyte Li–S batteries. First, the key challenges arising from lean‐electrolyte conditions are discussed in detail. Then, the approaches and the recent progress to reduce electrolyte usage, including optimization of electrode porosity and ion conduction, the introduction of electrocatalysis, exploration of new active materials, electrolyte regulation, and Li metal protection are reviewed. Finally, future research directions in lean‐electrolyte Li–S batteries are proposed. [ABSTRACT FROM AUTHOR]

Despite lithium‐sulfur (Li‐S) batteries possessing ultrahigh energy density as great promising energy storage devices, the suppressing shuttle effect and improving sulfur redox reaction (SROR) are vital for their practical application. Developing high‐activity electrocatalysts for enhancing the SROR kinetics is a major challenge for the application of Li‐S batteries. Herein, single‐molecule iron phthalocyanine species are anchored on the N and P dual‐doped porous carbon nanosheets (Fe‐NPPC) via axial Fe‐N coordination to optimize the electronic structure of active centers. The Fe‐NPPC can promote the catalytic conversion of polysulfides by modulation of the electronic density in active moieties, endowing the Li‐S battery with a high reversible capacity of 1023 mAh g−1 at 1 C as well as an ultralow capacity decay of 0.035% per cycle over 1500 cycles. Even with a high sulfur loading of 7.1 mg cm−2, the Li‐S battery delivers a high areal capacity of 4.8 mAh cm−2 after 150 cycles at 0.2 C. With further increasing the sulfur loading to 9.2 mg cm−2, an excellent areal capacity of up to 9.3 mAh cm−2 is obtained at 0.1 C. [ABSTRACT FROM AUTHOR]

Poor electrical conductivity and the volume expansion of sulfur, shuttle effect of lithium polysulfides are key challenges for lithium-sulfur (Li–S) batteries. Due to good conductivity and adjustable pore structure, expanded graphite (EG) is considered an excellent candidate as host for sulfur. In this work, sulfur was encapsulated into the pore of Co3O4-doped expanded graphite via a pressure swing-assisted impregnation, and the surface sulfur was removed by rapid sublimation. Benefitting from the excellent electrical conductivity of expanded graphite and the chemical bonding between Co3O4 and polysulfides, the shuttle effect was significantly suppressed. The prepared Co3O4-EG-S composite delivered a discharge-specific capacity of 1379 mAh g−1 at 0.1 C and 985 mAh g−1 at 1 C. After 200 cycles at 0.2 C, the capacity remained up to 661 mAh g−1 while the coulombic efficiency maintained above 98%. This work can provide an idea for restraining the shuttle effect in Li–S batteries. [ABSTRACT FROM AUTHOR]

Reduction of plastic wastes in the environment and solving the energy demands from renewable sources are two important challenging tasks of this century. Modern day lives are highly entangled with polymers, however handling the huge wastes from plastics is also a serious concern. Translating the plastic wastes to useful products such as graphene can be an alternative for nonbiodegradable polymer wastes. Efficient energy storage devices, for instance, batteries are required for storing the renewable energies. With the aim of regulating these issues, we report, for the first time, the preparation of high energy cathode materials from the nanocomposites (NCs) having polyaniline (PANI), waste‐derived graphene (WDG) derived from plastic waste and sulfur (S) for Li–S battery applications. We compare the electrochemical properties of cathodes derived from WDG/S and WDG/PANI/S in Li–S batteries. The specific discharge capacity of WDG/PANI/S at 0.1 C was obtained to be 880 mAhg−1 normalized to sulfur mass at 1st cycle, 472 mAhg−1 at 100th cycle, and 400 mAhg−1 at 160th cycle. The rate capability is also found to be good at C‐rates less than 0.5 C. We found that WDG/PANI/S showed decent electrochemical properties when compared with the reference sample, WDG/S at similar sulfur loading without PANI modification. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries have attracted increased interest because of the high theoretical energy density, low cost, and environmental friendliness. Conducting polymers (CPs), as one of the most promising materials used in Li–S batteries, can not only facilitate electron transfer and buffer the large volumetric change of sulfur benefiting from their porous structure and excellent flexibility, but also enable stronger physical/chemical adsorption capacity toward polysulfides (LiPSs) when doped with abundant heteroatoms to promote the sulfur redox kinetics and achieve the high sulfur loading. This review firstly introduces the properties of various CPs including structural CPs (polypyrrole (PPy), polyaniline (PANi), polyethylene dioxothiophene [PEDOT]) and compound CPs (polyethylene oxide (PEO), polyvinyl alcohol (PVA) and poly(acrylic acid) [PAA]), and their application potential in Li–S batteries. Furthermore, the research progress of various CPs in different components (cathode, separator, and interlayer) of Li–S batteries is systematically summarized. Finally, the application perspective of the CPs in Li–S batteries as a potential guidance is comprehensively discussed. [ABSTRACT FROM AUTHOR]

Agglomeration of carbon nanotubes (CNTs) extremely hampers utilization of active surface area and impedes sulfur loading, which limit their application in high–energy‐density lithium–sulfur (Li–S) batteries. Herein, N‐doped carbon nanotubes with Co/Co2P nanoparticles encapsulated inside and vertical graphene (VG) nanosheets grown outside (CCP@NCNT@VGs) are prepared as efficient sulfur carriers for Li–S batteries. The Co/Co2P nanoparticles encapsulated in the NCNTs could strongly anchor polysulfide and efficiently catalyze the conversion of polysulfides to Li2S, while the 3D hierarchical conductive network constructed by the vertical graphene nanosheets and NCNT quickly transfer electrons and improve the conversion kinetics of polysulfides. The as‐synthesized hierarchical structure combines conductivity with anchoring and catalysis, significantly elevating the electrochemical performance of the Li–S batteries. Hence, even at a high mass loading of 7 mg cm−2, the CCP@NCNT@VGs/S electrode with limited electrolyte/sulfur ratio (4 μL mg−1) exhibits a high areal capacity of 7 mAh cm−2, showing great application potential in the field of energy storage. [ABSTRACT FROM AUTHOR]

Abstract The chief culprit impeding the commercialization of lithium–sulfur (Li–S) batteries is the parasitic shuttle effect and restricted redox kinetics of lithium polysulfides (LiPSs). To circumvent these key stumbling blocks, incorporating electrocatalysts with rational electronic structure modulation into sulfur cathode plays a decisive role in vitalizing the higher electrocatalytic activity to promote sulfur utilization efficiency. Breaking the stereotype of contemporary electrocatalyst design kept on pretreatment, field‐assisted electrocatalysts offer strategic advantages in dynamically controllable electrochemical reactions that might be thorny to regulate in conventional electrochemical processes. However, the highly interdisciplinary field‐assisted electrochemistry puzzles researchers for a fundamental understanding of the ambiguous correlations among electronic structure, surface adsorption properties, and catalytic performance. In this review, the mechanisms, functionality explorations, and advantages of field‐assisted electrocatalysts including electric, magnetic, light, thermal, and strain fields in Li–S batteries have been summarized. By demonstrating pioneering work for customized geometric configuration, energy band engineering, and optimal microenvironment arrangement in response to decreased activation energy and enriched reactant concentration for accelerated sulfur redox kinetics, cutting‐edge insights into the holistic periscope of charge‐spin‐orbital‐lattice interplay between LiPSs and electrocatalysts are scrutinized, which aspires to advance the comprehensive understanding of the complex electrochemistry of Li–S batteries. Finally, future perspectives are provided to inspire innovations capable of defeating existing restrictions.

Highlights The all-solid-state thin-film Li-S battery has been successfully developed by stacking VGs-Li2S cathode, lithium-phosphorous-oxynitride (LiPON) solid electrolyte, and Li anode. The obtained VGs-Li2S thin-film cathode exhibits excellent long-term cycling stability (more than 3,000 cycles), and an exceptional high temperature tolerance (up to 60 °C). The superb electrochemical performance can be attributed to the favorable compatibility and outstanding interfacial stability between VGs-Li2S thin film and LiPON.