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Lithium–sulfur (Li–S) batteries are considered as a substitute for conventional batteries as they are the most promising next‐generation energy‐storage system due to their high energy densities. However, their short cycling life, limited sulfur loading, severe polysulfide shuttling, and low sulfur utilization critically impede grid‐level‐storage energy techniques in Li–S batteries. The lithium shuttle effect results in rapid capacity fading and battery failure. The design and fabrication of sulfur hosts are key points to eliminate the aforementioned issues, especially the shuttle effect. In the past decade, spatial encapsulation and chemical interaction have improved the adsorption capacity of lithium polysulfides for the sulfur hosts and thus prolonged the lifetime of Li–S batteries. In an attempt to promote future research on the sulfur cathode and foster breakthroughs in Li–S batteries, recent achievements are highlighted, mechanical insights are discussed, and the remaining challenges and future research directions in the innovation of sulfur cathodes are identified.  相似文献   

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Lithium–sulfur (Li–S) batteries have been strongly considered as one of the most promising future energy storage systems because of ultrahigh theoretical energy density of 2600 Wh kg−1. The natural abundance, affordable cost, and environmental benignity of elemental sulfur constitute additional advantages. However, complicated reaction behaviors at working electrode/electrolyte interfaces that involve multiphase conversion and multistep ion/electron diffusion during sulfur redox reactions have impeded the thorough understanding of Li–S chemistry and its practical applications. This perspective article highlights the influence of the ion/electron transport and reaction regulation through electrocatalysis or redox mediation at electrode/electrolyte interfaces on various interfacial sulfur redox reactions (liquid–liquid–solid interconversion between soluble lithium polysulfide with different chain lengths and insoluble lithium sulfides in liquid‐electrolyte Li–S batteries and direct solid–solid conversion between sulfur and Li2S in all‐solid‐state Li–S batteries). The current status, existing challenges, and future directions are discussed and prospected, aiming at shedding fresh light on fundamental understanding of interfacial sulfur redox reactions and guiding the rational design of electrode/electrolyte interfaces for next‐generation Li–S batteries with high energy density and long cycle life.  相似文献   

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Lithium–sulfur (Li–S) batteries have arousing interest because of their high theoretical energy density. However, they often suffer from sluggish conversion of lithium polysulfides (LiPS) during the charge/discharge process. Single nickel (Ni) atoms on nitrogen‐doped graphene (Ni@NG) with Ni–N4 structure are prepared and introduced to modify the separators of Li–S batteries. The oxidized Ni sites of the Ni–N4 structure act as polysulfide traps, efficiently accommodating polysulfide ion electrons by forming strong Sx 2????Ni? N bonding. Additionally, charge transfer between the LiPS and oxidized Ni sites endows the LiPS on Ni@NG with low free energy and decomposition energy barrier in an electrochemical process, accelerating the kinetic conversion of LiPS during the charge/discharge process. Furthermore, the large binding energy of LiPS on Ni@NG also shows its ability to immobilize the LiPS and further suppresses the undesirable shuttle effect. Therefore, a Li–S battery based on a Ni@NG modified separator exhibits excellent rate performance and stable cycling life with only 0.06% capacity decay per cycle. It affords fresh insights for developing single‐atom catalysts to accelerate the kinetic conversion of LiPS for highly stable Li–S batteries.  相似文献   

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Lithium‐sulfur (Li? S) batteries are strongly considered as the next‐generation rechargeable cells. However, both the shuttle of lithium polysulfides (LiPSs) and sluggish kinetics in random deposition of lithium sulfides (Li2S) significantly degrade the capacity, rate performance, and cycling life of Li? S cells. Herein, bifunctional Ba0.5Sr0.5Co0.8Fe0.2O3?δ perovskite nanoparticles (PrNPs) are proposed as a promoter to immobilize LiPSs and guide the deposition of Li2S in a Li? S cell. The oxygen vacancy in PrNPs increases the metal reactivity to anchor LiPSs, and co‐existence of lithiophilic (O) and sulfiphilic (Sr) sites in PrNP favor the dual‐bonding (Li? O and Sr? S bonds) to anchor LiPSs. The high catalytic nature of PrNP facilitates the kinetics of LiPS redox reaction. The PrNP with intrinsic LiPS affinity serves as nucleation sites for Li2S deposition and guides its uniform propagation. Therefore, the bifunctional LiPS promoter in Li? S cell yields high rate performance and ultralow capacity decay rate of 0.062% (a quarter of pristine Li? S cells). The proposed strategy to immobilize LiPSs, promotes the conversion of LiPS, and regulates deposition of Li2S by an emerging perovskite promoter and is also expected to be applied in other energy conversion and storage devices based on multi‐electron redox reactions.  相似文献   

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Regulating the solid product growth is critical for achieving high capacities in rechargeable batteries based upon multiphase and multielectron dissolution–precipitation chemistries (e.g., lithium–sulfur chemistry). The intrinsic redox mediators, polysulfides, are insufficient for effective regulation due to the dynamically changed species and concentration. Herein cobaltocene (CoCp2) is introduced as a persistent extrinsic redox mediator to dictate an alternative growing pathway toward three‐dimensional lithium sulfide growth, which enables at most 8.1 times enhancement in discharge capacities at harsh conditions of high‐rate (>1 C) or electrolyte‐lean operation (electrolyte/sulfur ratio of 4.7 µL mgS−1). The faster kinetics and higher diffusivity of CoCp2 play an essential role in regulating lithium sulfide growth and increasing discharge capacities. This work not only illustrates an effective strategy to increase the capacity of high‐rate or electrolyte‐lean lithium–sulfur batteries but also paves a way toward the rational design of novel redox mediators for dissolution–precipitation energy chemistries.  相似文献   

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A high lithium conductive MoS2/Celgard composite separator is reported as efficient polysulfides barrier in Li–S batteries. Significantly, thanks to the high density of lithium ions on MoS2 surface, this composite separator shows high lithium conductivity, fast lithium diffusion, and facile lithium transference. When used in Li–S batteries, the separator is proven to be highly efficient for depressing polysulfides shuttle, leading to high and long cycle stability. With 65% of sulfur loading, the device with MoS2/Celgard separator delivers an initial capacity of 808 mAh g?1 and a substantial capacity of 401 mAh g?1 after 600 cycles, corresponding to only 0.083% of capacity decay per cycle that is comparable to the best reported result so far. In addition, the Coulombic efficiency remains more than 99.5% during all 600 cycles, disclosing an efficient ionic sieve preventing polysulfides migration to the anode while having negligible influence on Li+ ions transfer across the separator. The strategy demonstrated in this work will open the door toward developing efficient separators with flexible 2D materials beyond graphene for energy‐storage devices.  相似文献   

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Intermediate polysulfides (Sn, where n = 2–8) play a critical role in both mechanistic understanding and performance improvement of lithium–sulfur batteries. The rational management of polysulfides is of profound significance for high‐efficiency sulfur electrochemistry. Here, the key roles of polysulfides are discussed, with regard to their status, behavior, and their correspondingimpact on the lithium–sulfur system. Two schools of thoughts for polysulfide management are proposed, their advantages and disadvantages are compared, and future developments are discussed.  相似文献   

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The physiochemical properties of the carbon host matrix and their sulfur loadings play a major role in the electrochemical performance of lithium–sulfur batteries. A highly sulfur (S) loaded (75 wt%) carbon matrix (S/nitrogen rich carbon host matrix (NGC)) has been designed, with hierarchically organized micro/mesopore structures containing nitrogen and oxygen functional groups, and using metal oxide nanostructured templates. The S/NGC electrodes give reversible capacities of 868 and 666 mAh g−1 at C/5 current rates, with sulfur loading of 2.2 and 3.4 mg cm−2, respectively. Based on the advantages of the hierarchically organized porous structure and heteroatom doping, S/NGC electrode shows long cycling stability (0.03% capacity decay per cycle in the first 1000 cycles) with high coulombic efficiency (>99%), which is an improvement by a factor of two compared with a sulfur/graphene cathode. Further, the charge/discharge mechanism of the cell is investigated in detail by in situ Raman and ex situ X‐ray photoelectron spectroscopy. The presence of nitrogen on the carbon support is found to make the bond formation easier between sulfur and oxygen functional groups existing at the carbon support, which is supposed to play a major role along with hierarchically organized porous structure, for the prevention of sulfur/polysulfides species dissolution to the anode side.  相似文献   

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Lithium–sulfur batteries have gained incredible increasing attention due to their high theoretical energy density and comparable low cost. Although great advances are made in optimizing Li–S batteries via rational design of the composition and architecture, daunting challenges remain to restrain the shuttle‐effect issue associated with the extremely complicated “solid‐liquid‐solid” reaction routes. In recent years, researchers have reached a consensus that the characterization of practical working mechanisms of Li–S batteries is an important prerequisite for optimizing their performance. Numerous in situ/operando spectroscopic techniques with light sources of 10−10–103 m wavelengths, such as X‐rays, UV–vis, nuclear magnetic resonance (radio), infrared, etc., are introduced to supply real‐time and console‐displayed signals related to the reaction variations of Li–S batteries, thus helping to put forward further optimization strategies in the internal designs. This review systematically summarizes the state‐of‐the‐art in the optimal design of Li–S batteries with the aid of in situ/operando spectroscopic characterizations, including the progress in cathodes, binders, interlayers, electrolytes, and Li metal anodes, aiming to show the powerful ability of in situ/operando spectroscopic techniques in revealing the working and degradation mechanism and scientifically guiding the further optimal design of Li–S batteries.  相似文献   

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Lithium–sulfur (Li–S) batteries, with high theoretical energy density and the low cost of sulfur, have the most appeal as the successor to lithium‐ion batteries. Their performance to date is however undermined by the redox shuttling of dissolved polysulfides between the cathode and anode during battery cycling. Though substantial improvements are made with the use of solid additives, which are described in the literature as adsorbents, mediators, or catalysts for the sulfur cathodes, it is still a challenge to differentiate the specific functions suggested by their names due to the incomplete understanding of the 16‐electron sulfur electrochemical reaction. Here the research on solid additives in the development timeline of Li–S batteries is reviewed, and some perspectives on the deployment method are provided which can optimize the performance of solid additives (catalysts, in particular) in Li–S batteries.  相似文献   

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Lithium metal–sulfur (Li–S) batteries are attracting broad interest because of their high capacity. However, the batteries experience the polysulfide shuttle effect in cathode and dendrite growth in the Li metal anode. Herein, a bifunctional and tunable mesoporous carbon sphere (MCS) that simultaneously boosts the performance of the sulfur cathode and the Li anode is designed. The MCS homogenizes the flux of Li ions and inhibits the growth of Li dendrites due to its honeycomb structure with high surface area and abundance of nitrogen sites. The Li@MCS cell exhibits a small overpotential of 29 mV and long cycling performance of 350 h under the current density of 1 mA cm‐2. Upon covering one layer of amorphous carbon on the MCS (CMCS), an individual carbon cage is able to encapsulate sulfur inside and reduce the polysulfide shuttle, which improves the cycling stability of the Li–S battery. As a result, the S@CMCS has a maximum capacity of 411 mAh g‐1 for 200 cycles at a current density of 3350 mA g‐1. Based on the excellent performance, the full Li–S cell assembled with Li@MCS anode and S@CMCS cathode shows much higher capacity than a cell assembled with Li@Cu anode and S@CMCS cathode.  相似文献   

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For the first time a new strategy is reported to improve the volumetric capacity and Coulombic efficiency by selenium doping for lithium–organosulfur batteries. Selenium‐doped cathodes with four sulfur atoms and one selenium atom (as the doped heteroatom) in the confined structure are designed and synthesized; this structure exhibits greatly improved volumetric/areal capacities, and a Coulombic efficiency of almost 100% for highly stable lithium–organosulfur batteries. The doping of Se significantly enhances the electronic conductivity of battery electrodes by a factor of 6.2 compared to pure sulfur electrodes, and completely restricts the production of long‐chain lithium polysulfides. This allows achievement of a high gravimetric capacity of 700 mAh g?1 close to its theoretical mass capacity, an exceptional volumetric capacity of 2457 mAh cm?3, and excellent capacity retention of 92% after 400 cycles. Shuttle effect is efficiently weakened since no long‐chain polysulfides are detected from in situ UV/vis results throughout the entire cycling process arising from selenium doping, which is theoretically confirmed by density functional theory calculations.  相似文献   

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Host materials that can provide both a strong absorbability of soluble intermediate polysulfides and a high electronic conductivity are in high demand to realize practical applications of Li–S batteries. Here, the rational design of an N‐doped carbon comb (NCC) as a new type of sulfur host for Li–S batteries, delivering a favorable performance, particularly a good cycling stability and rate capability, is reported. A novel dodecylamine micelle‐induced self‐assembling method is first proposed for constructing the NCC host which is built from close‐packed hollow submicron carbon spheres. The interconnected carbon frameworks create good electrical conductive pathways. In addition, the high porosity and the N doping of the NCC host effectively suppress sulfur losses during cycling through synergistic physisorption and chemisorption effects. As a result, cathodes with 71 wt% of sulfur deposited in the NCC host possess superior capacities of 1090 and 553 mAh g−1 at 0.1 and 2 C, respectively. After 300 cycles at 1 C, a reversible capacity of 562 mAh g−1 is retained. Even at a high sulfur loading of 83 wt%, favorable performance is realized.  相似文献   

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